Variation in the diversity-productivity relationship in young forests of the eastern United States

The diversity–productivity relationship has not been studied as extensively in forests as in other ecosystems. We address this gap in our knowledge by examining the relationship of productivity (primarily the periodic annual increment in aboveground biomass, but also the mean annual increment) with five species diversity indices, stand, and environmental factors. We used 967 naturally regenerated Forest Inventory and Analysis plots with stand age ≤30 years, located in the conterminous thirty-one eastern states, and satisfying strict selection requirements. Generally, mixed-species (heterospecific) stands were as productive as or even somewhat more productive than pure (monospecific) stands. The periodic and mean annual increments were both positively correlated with species richness (R2 = 0.04 and 0.20, p<0.001). Similarly, the zero-order and partial correlations with productivity were positive for four of the diversity indices (species richness, functional diversity, phylogenetic diversity, and phylogenetic species richness) and not significant for the fifth (functional dispersion). Greater diversity was more important on low-productivity sites and in stands with low stocking. As forests generally get more diverse and productive away from the poles, we tested if the nature of the productivity-diversity relationship changed latitudinally. Productivity was weakly positively correlated with four of the diversity indices north of 40° latitude, but weakly negatively with three of the indices to the south. Our examination of the productivity–diversity relationship in stands containing either of the two most dominant species, quaking aspen or loblolly pine, revealed that pure loblolly pine stands were somewhat more productive than only three of the eight mixtures with loblolly in the composition, while pure aspen stands were no more productive than any of the aspen mixtures. Overall, monospecific stands did not seem to have a clear productivity advantage over mixtures. The findings of this study have implications for woody biomass production, carbon sequestration by forests, and biodiversity conservation.

The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service.

Forest Inventory and Analysis (FIA) is a continuing endeavor mandated by Congress in the Forest and Rangeland Renewable Resources Planning Act of 1974 and the McSweeney-McNary Forest Research
Act of 1928. FIA's primary objective is to determine the extent, condition, volume, growth, and depletion of timber on the Nation's forest land. Before 1999, all inventories were conducted on a periodic basis. The passage of the 1998 Farm Bill requires FIA to collect data annually on plots within each State. This kind of up-to-date information is essential to frame realistic forest policies and programs. USDA Forest Service regional research stations are responsible for conducting these inventories and publishing summary reports for individual States.
In addition to published reports, the Forest Service provides data collected in each inventory to those interested in further analysis. This report describes a standard format in which data can be obtained. This standard format, referred to as the Forest Inventory and Analysis Database (FIADB) structure, was developed to provide users with as much data as possible in a consistent manner among States. A number of inventories conducted prior to the implementation of the annual inventory are available in the FIADB. However, various data attributes may be empty or the items may have been collected or computed differently. Annual inventories use a common plot design and common data collection procedures nationwide, resulting in greater consistency among FIA work units than earlier inventories. Data field definitions note inconsistencies caused by different sampling designs and processing methods.
This manual has four chapters. The remainder of chapter 1 includes general introductions to the FIA program and the FIA database, including brief histories of both. It provides a convenient overview for those who have an interest in using FIA data, but have not yet become familiar with the FIA program. Chapter 2 provides descriptions of FIA sampling methods, including plot location and design, data measurement and computation, and general estimation procedures. Chapter 3 describes the tables that comprise the database, the attributes stored in each table, and the linkages between tables. Descriptions of the attributes, their data format, valid values, and other important details are given, but the appropriate field manuals should be consulted for exact specifications regarding data collection methods. Users with a good understanding of chapter 3 and fundamental database management skills should be able to conduct a wide range of analyses. Chapter 4 explains the standard methods used to compile population-level estimates from FIADB, and applies the new estimation procedures documented by Bechtold and Patterson (2005). These procedures are based on adoption of the annual inventory system and the mapped plot design, and constitute a major change when compared to previous compilation procedures. However, the new compilation procedures should allow more flexible analyses, especially as additional panels are completed under the annual inventory system.
There are several conventions used in this manual. The names of attributes (i.e., columns within tables) and table names appear in capital letters (e.g., PLOT table). Some attribute names appear in two or more tables. In most cases, such as the State code (STATECD), the attribute has the same definition in all tables. However, there are situations where attributes with the same name are defined differently in each table. One such example is the VALUE attribute in the REF_FOREST_TYPE table, which is used to identify the forest type and refers to appendix D. However, the VALUE attribute in the REF_UNIT table is used to indicate the FIA survey unit identification number from appendix C. In most cases, such as in the table descriptions in chapter 3, the attribute name will be used alone and the affiliation with a particular table is implied by the context. In cases where an attribute name has a different meaning in two or more tables, a compound naming convention, using the table name followed by the attribute name, will be used. In the VALUE attribute example, the name REF_FOREST_TYPE.VALUE refers to the VALUE attribute in the REF_FOREST_TYPE table, while REF_UNIT.VALUE refers to the VALUE attribute in the REF_UNIT table.

The FIA Program
The FIA program is mandated by Congress in the Forest and Rangeland Renewable Resources Planning Act of 1974 and the McSweeney-McNary Forest Research Act of 1928. The mission of FIA is to determine the extent, condition, volume, growth, and depletions of timber on the Nation's forest land. FIA is the only program that collects, publishes, and analyzes data from all ownerships of forest land in the United States (Smith 2002). Throughout the 80-year history of the program, inventories have been conducted by a number of geographically dispersed FIA work units. Starting in 1929, FIA accomplished its mission by conducting periodic forest inventories on a Stateby-State basis. With the completion of Arizona, New Mexico, and Nevada in 1962, all 48 coterminous States had at least one periodic inventory (Van Hooser and others 1993). Repeat intervals for inventorying individual States have varied widely. By the late 1990s, most States had been inventoried more than once under the periodic inventory system; however, not all periodic data are available in electronic form (appendix I lists all periodic data available in the FIADB and the year in which annual inventory began). With the passage of the 1998 Farm Bill, the FIA program was required to move from a periodic inventory to an annualized system, with a portion of all plots within a State measured each year (Gillespie 1999). Starting in 1999, States were phased into the annual inventory system (appendix I). At the time of publication of this document, annual inventory has not yet been started in Wyoming and Interior Alaska. Although the 1998 Farm Bill specified that 20 percent of the plots within each State would be visited annually, funding limitations have resulted in the actual portion of plots measured annually ranging between 10 and 20 percent, depending on the State.
Periodic and annual data are analyzed to produce reports at State, regional, and national levels. In addition to published reports, data are made available to the public for those who are interested in conducting their own analyses. Downloadable data, available online at http://fia.fs.fed.us/toolsdata/, follow the format described in this document. Also available at this site are tools to make population estimates. The web-based EVALIDator tool or the Forest Inventory Data Online (FIDO) tool provide interactive access to the FIADB.

The FIA Database
The Forest Inventory and Analysis Database (FIADB) was developed to provide users with data in a consistent format, spanning all States and inventories. The first version of FIADB replaced two FIA regional databases; the Eastern States (Eastwide database) documented by Hansen and others (1992), and Western States (Westwide database) documented by Woudenberg and Farrenkopf (1995). A new national plot design (see chapter 2) provided the impetus for replacing these two databases, and FIA work units adopted the new design in all State inventories initiated after 1998. The FIADB table structure is currently derived from the National Information Management System (NIMS), which was designed to process and store annual inventory data. This is the fourth version of the single national FIA database to be released. A number of changes in the FIADB structure have been made to accommodate the data processing and storage requirements of NIMS. As a result, data from periodic inventories are stored in a format consistent with annual inventory data.
FIADB files are available for periodic inventory data collected as early as 1977 (see appendix I). A wide variety of plot designs and regionally defined attributes were used in periodic inventories, often differing by State. Because of this, some data attributes may not be populated or certain data may have been collected or computed differently. During some periodic inventories, ground plot data were collected on nonreserved timberland only. Low productivity forest land, reserved (areas reserved from timber harvesting), and nonforested areas usually were not ground sampled. To account for the total area of a State, "place holder" plots were created to represent these nonsampled areas, which are identified by plot design code 999 in FIADB (PLOT.DESIGNCD = 999). For these plots, many attributes that are normally populated for forested plots will be blank. Users should be aware that while place holder plots account for the area of nonsampled forest land, they do not account for the corresponding forest attributes (such as volume, growth, or mortality) that may exist in those areas.
Annual inventories, initiated sometime after 1999 depending on the State, use a nationally standardized plot design and common data collection procedures resulting in greater consistency among FIA work units than earlier inventories. However, as part of a continuing effort to improve the inventory, some changes in methodology and attribute definitions have been implemented after the new design was put into practice. Beginning in 1998, FIA started using a National Field Guide referenced as Field Guide 1.0. The database contains an attribute labeled MANUAL that stores the version number of the field guide under which the data were collected. When both the plot design is coded as being the national design (PLOT.DESIGNCD = 1) and the field guide is coded with a number greater than or equal to 1, certain attributes are defined as being "core" while others are allowed to be "core optional." Core attributes must be collected by every FIA work unit, using the same definition and set of codes. In contrast, collection of core optional attributes are decided upon by individual FIA work units, using the same national protocol, predefined definition, and set of codes. Many attributes, regardless of whether or not they are core or core optional, are only populated for forested conditions, and are blank for other conditions (such as nonforest or water). Attributes described in chapter 3 are noted if they are core optional.
Users who wish to analyze data using aggregations of multiple State inventories or multiple inventories within States should become familiar with changes in methodology and attribute definitions (see chapters 2 and 3). For each attribute in the current version of FIADB, an effort has been made to provide the current definition of the attribute, as well as any variations in definition that may have been used among various FIA work units. In other words, although inventory data have been made available in a common data format, users should be aware of differences that might affect their analyses.

Changes From the Previous Database Version
Database users should also be aware that changes are made for each version of FIADB. Sometimes the changes are minimal, such as simply rewriting explanatory text for clarification or adding new codes to a particular attribute. Database tables and/or attributes may be added or removed. In this release (4.0), a number of reference tables have been added. Also, two tables were added to modify the way population estimates are handled. Another important table addition is the Subplot Condition Change Matrix table that tracks changes in any condition class attribute between two visits to a plot. In appendix F, several changes were made in the SPGRPCD column. Tables 1-5 summarize the major modifications to FIADB Version 4.0.   PLOT  GROWCD  GROW_TYP_CD  PLOT  MORTCD  MORT_TYP_CD  COND  TRTCD1_SRS  HARVEST_TYPE1_SRS  COND  TRTCD2_SRS  HARVEST_TYPE2_SRS  COND  TRTCD3_SRS  HARVEST_TYPE3_SRS  SUBPLOT  STATUSCD  SUBP_STATUS_CD  SITETREE COND_CLASS_LIST CONDLIST A change was made in the stocking equation assignment for various tree species and was applied to all annual inventory plot data. This change can result in a different computed forest type for a given plot. Several new forest types have been added and some changes were made in the way forest types are grouped.

Chapter 2 --FIA Sampling and Estimation Procedures
To use the FIADB effectively, users should acquire a basic understanding of FIA sampling and estimation procedures. Generally described, FIA uses what may be characterized as a three-phase sampling scheme. Phase 1 (P1) is used for stratification, while Phase 2 (P2) consists of plots that are visited or photo-interpreted. A subset of Phase 2 plots are designated as Phase 3 (P3) plots (formerly known as Forest Health Monitoring (FHM) plots) where additional health indicator attributes are collected. Phases 1 and 2 are described in this chapter, but Phase 3 is described in a separate user's manual (Woodall and others 2010). The exception is P3 crown attributes, which are described in the TREE table of this document.

Sampling and Stratification Methodology
Remote Sensing (P1) The basic level of inventory in the FIA program is the State, which begins with the interpretation of a remotely sensed sample, referred to as Phase 1 (P1). The intent of P1 is to classify the land into various remote sensing classes for the purpose of developing meaningful strata. A stratum is a group of plots that have the same or similar remote sensing classifications. Stratification is a statistical technique used by FIA to aggregate Phase 2 ground samples into groups to reduce variance when stratified estimation methods are used. The total area of the estimation unit is assumed to be known.
Each Phase 2 ground plot is assigned to a stratum and the weight of the stratum is based on the proportion of the stratum within the estimation unit. Estimates of population totals are then based on the sum of the product of the known total area, the stratum weight, and the mean of the plot level attribute of interest for each stratum. The expansion factor for each stratum within the estimation unit is the product of the known total area and the stratum weight divided by the number of Phase 2 plots in the stratum.
Selection criteria for remote sensing classes and computation of area expansion factors differ from State to State. Users interested in the details of how these expansion factors are assigned to ground plots for a particular State should contact the appropriate FIA work unit (see table 6).
Ground Sampling (P2) FIA ground plots, or Phase 2 plots, are designed to cover a 1-acre sample area; however, not all trees on the acre are measured. Ground plots may be new plots that have never been measured, or re-measurement plots that were measured during one or more previous inventories. Recent inventories use a nationally standard, fixed-radius plot layout for sample tree selection (see figure 2). Various arrangements of fixed-radius and variable-radius (prism) subplots were used to select sample trees in older inventories.

Plot Location
The FIADB includes coordinates for every plot location in the database, whether it is forested or not, but these are not the precise locations of the plot centers. In an amendment to the Food Security Act of 1985 (reference 7 USC 2276 § 1770), Congress directed FIA to ensure the privacy of private landowners. Exact plot coordinates could be used in conjunction with other publicly available data to link plot data to specific landowners, in violation of requirements set by Congress. In addition to the issue of private landowner privacy, the FIA program had concerns about plot integrity and vandalism of plot locations on public lands. A revised policy has been implemented and methods for making approximate coordinates available for all plots have been developed. These methods are collectively known as "fuzzing and swapping" (Lister and others 2005).
In the past, FIA provided approximate coordinates for its periodic data in the FIADB. These coordinates were within 1.0 mile of the exact plot location (this is called fuzzing). However, because some private individuals own extensive amounts of land in certain counties, the data could still be linked to these owners. In order to maintain the privacy requirements specified in the amendments to the Food Security Act of 1985, up to 20 percent of the private plot coordinates are swapped with another similar private plot within the same county (this is called swapping). This method creates sufficient uncertainty at the scale of the individual landowner such that privacy requirements are met. It also ensures that county summaries and any breakdowns by categories, such as ownership class, will be the same as when using the true plot locations. This is because only the coordinates of the plot are swapped -all the other plot characteristics remain the same. The only difference will occur when users want to subdivide a county using a polygon. Even then, results will be similar because swapped plots are chosen to be similar based on attributes such as forest type, stand-size class, latitude, and longitude (each FIA work unit has chosen its own attributes for defining similarity).
For plot data collected under the current plot design, plot numbers are reassigned to sever the link to other coordinates stored in the FIADB prior to the change in the law. Private plots are also swapped using the method described above; remeasured plots are swapped independent of the periodic data. All plot coordinates are fuzzed, but less than before -within 0.5 mile for most plots and up to 1.0 mile on a small subset of them. This was done to make it difficult to locate the plot on the ground, while maintaining a good correlation between the plot data and map-based characteristics. Figure 2. The FIA mapped plot design. Subplot 1 is the center of the cluster with subplots 2, 3, and 4 located 120 feet away at azimuths of 360°, 120°, and 240°, respectively.
For most user applications, such as woodbasket analyses and estimates of other large areas, fuzzed and swapped coordinates provide a sufficient level of accuracy. However, some FIA customers require more precision of plot locations in order to perform analyses by user-defined polygons and for relating FIA plot data to other map-based information, such as soils maps and satellite imagery. In order to accommodate this need, FIA provides spatial data services that allow most of the desired analyses while meeting privacy requirements. The possibilities and limitations for these types of analyses are case-specific, so interested users should contact their local FIA work unit for more information.

Plot Designs
The current national standard FIA plot design was originally developed for the Forest Health Monitoring program (Scott and others 1993). It was adopted by FIA in the mid-1990s and used for the last few periodic inventories and all annual inventories. The standard plot consists of four 24.0foot radius subplots (approximately 0.0415 or 1/24 acre) (see figure 2), on which trees 5.0 inches and greater in diameter are measured. Within each of these subplots is nested a 6.8-foot radius microplot (approximately 1/300th acre) on which trees smaller than 5.0 inches in diameter are measured. A core optional variant of the standard design includes four "macroplots," each with a radius of 58.9 feet (approximately 1/4 acre) that originate at the centers of the 24.0-foot radius subplots. Breakpoint diameters between the 24-foot radius subplots and the macroplots vary and are specified in the macroplot breakpoint diameter attribute (PLOT.MACRO_BREAKPOINT_DIA).

Measured, Assigned, and Computed Attributes
In addition to attributes that are collected in the field, FIADB includes attributes that are populated in the office. Examples of field attributes include tree diameter and height, and slope and aspect of the plot and subplot. Attributes that are populated in the office include assigned attributes, such as county and owner group codes, or computed attributes, such as tree and area expansion factors, and tree volumes.
For measured attributes, this document provides only basic information on the methodology used in the field. The authoritative source for methodology is the Forest Inventory and Analysis National Core Field Guide used during the inventory in which the data were collected (see http://www.fia.fs.fed.us/library/field-guides-methods-proc/) . The MANUAL attribute in the PLOT table documents the version number where data collection protocols can be found.
Values of attributes that are assigned in the office are determined in several ways, depending on the attribute. For example, ownership may be determined using geographic data or local government records. Other attributes, such as Congressional District and Ecological Subsection are assigned values based on data management needs.
Some computed attributes in the database are derived using other attributes in the database. Ordinarily, such attributes would not be included in a database table because they could be Figure 3. The FIA mapped plot design. Subplot 1 is the center of the cluster with subplots 2, 3, and 4 located 120 feet away at azimuths of 360°, 120°, and 240°, respectively. When a plot straddles two or more conditions, the plot area is divided by condition.

Condition 1 Condition 3
Condition 2 computed using the supplied attributes. However, some data compilation routines are complex or vary within or among FIA work units, so these computed attributes are populated for the convenience of database users.
One example of a computed attribute is site index, which is computed at the condition level. Site index is generally a function of height and age, although other attributes may be used in conjunction. In addition, several different site index equations may be available for a species within its range. Height and age data are included in the TREE table, but only certain trees (see SITETREE  table) are included in the site index attribute that is reported for the condition. As a result, it would be time-consuming for users to replicate the process required to calculate site index at the condition level. For convenience, the condition (COND) table includes site index (SICOND), the species for which it is calculated (SISP), and the site index base age (SIBASE).
In most cases computed attributes should be sufficient for users' needs, because the equations and algorithms used to compute them have been determined by the FIA program to be the best available for the plot location. However, for most computed attributes the relevant tree and plot level attributes used to compute them are included in the database, so users may do their own calculations if desired.

Regional Attributes
A number of regionally specific attributes are available in FIADB. These regional attributes are identified by FIA work unit, both in the table structure description (e.g., the attribute is named with an extension such as NERS) and in the attribute description (e.g., the attribute description text contains the phrase "Only collected by…"). For specific questions about the data from a particular FIA work unit, please contact the individuals listed in table 6. Table 6. Contacts at individual FIA work units

Tree Expansion Factors
The expansion factor(s) used to scale each tree on a plot to a per-acre basis is dependent on the plot design. For fixed-plot designs, scaling is straightforward, with the number of trees per acre (TPA) represented by one tree equal to the inverse of the plot area in acres. The general formula is shown by equation [1]: [1] TPA = 1/(N*A) Where N is the number of subplots, and A is the area of each subplot.
For example, the TPA of each tree ≥5.0 inches in diameter occurring on the current plot design would be calculated using equation [2]: [2] TPA = 1/(4*0.04154172) = 6.018046 This expansion factor can be found in the TPA_UNADJ attribute in the TREE table (see chapter 3) for plots measured with the annual plot design. In variable-radius plot designs, the per-acre expansion factor is determined by the diameter of the tree, the basal area factor (BAF), and the number of subplots used in the plot design. The general formula is shown by equation [3]: [3] TPA = (BAF / 0.005454*DIA 2 )/N Where BAF is the variable-radius basal area factor in square feet, DIA is diameter of the tally tree in inches, and N is the number of subplots in the plot design.
For example, if a 11.5-inch tree is tallied using a 10 BAF prism on a variable-radius design plot that uses five subplots, the calculation is: [4] TPA = (10 / 0.005454*11.5 2 )/5 = 2.773 A 5.2-inch tree will have a greater expansion factor: [5] TPA = (10 / 0.005454*5.2 2 )/5 = 13.562 Although it is not necessary to calculate expansion factors for different plot designs because they are stored in TPA_UNADJ, information on plot design can be found by using the code from the DESIGNCD attribute in the PLOT table to look up the plot design specifications in appendix B.

Plot Area Expansion Factors
Some previous versions of FIADB have included area expansion factors in the PLOT table that were used to scale plot-level data to population-level estimates (see EXPCURR and related attributes in Miles and others 2001). In this version of FIADB, area expansion factors have been removed from the PLOT table. Instead, there is one area expansion factor (EXPNS) stored in the POP_STRATUM table. This change is needed because of the way annual inventory data are compiled. Under the annual inventory system, new plots are added each year. Adjustment factors that are used to compensate for denied access, inaccessible, and other reasons for not sampling may differ each time new data replaces older data. Both the number of acres each plot represents and the adjustments for the proportion of plots not sampled may change each year. In order to allow users to obtain population estimates for any grouping of data, an adjustment factor has been calculated and stored for each set of data being compiled. There is a separate adjustment factor for each fixed plot size: microplot, subplot, and macroplot. These attributes are also stored in the POP_STRATUM table. Each time the data are stratified differently, the adjustments and expansion factor may change. Therefore, FIA provides a different expansion factor every time the data are restratified.
FIA has chosen the term 'evaluation' to describe this process of storing different stratifications of data either for an individual set of data or for the changing sets of data through time. Each aggregation of data is given an evaluation identifier (EVALID). The user can select population estimates for the most current set of data or for previous sets of data. In addition to being able to calculate population estimates, users can now calculate sampling error information because FIA is storing all of the Phase 1 information used for the stratification. That information is stored for each estimation unit, which is usually a geographic subset of the State (see the POP_ESTN_UNIT table). For more information about evaluations and calculation of area expansion factors, see chapter 4.
A different method of population estimation is being implemented in this version of FIADB. In FIADB 3.0, users would select the appropriate evaluation sequence number (EVAL_CN_FOR_xxx) from the POP_EVAL_GRP table. This evaluation sequence number allowed them to select the appropriate plots and associated expansions. The newly added POP_EVAL_TYP table allows users to perform the similar queries, retrieving the same information, and will allow for a variety of evaluations to be added in the future. The previous method will continue to work in version 4.0.

Accuracy Standards
Forest inventory plans are designed to meet sampling error standards for area, volume, growth, and removals provided in the Forest Service directive (FSH 4809.11) known as the Forest Survey Handbook (U.S. Department of Agriculture 2008). These standards, along with other guidelines, are aimed at obtaining comprehensive and comparable information on timber resources for all parts of the country. FIA inventories are commonly designed to meet the specified sampling errors at the State level at the 67 percent confidence limit (one standard error). The Forest Survey Handbook mandates that the sampling error for area cannot exceed 3 percent error per 1 million acres of timberland. A 5 percent (Eastern United States) or 10 percent (Western United States) error per 1 billion cubic feet of growing-stock on timberland is applied to volume, removals, and net annual growth. Unlike the mandated sampling error for area, sampling errors for volume, removals, and growth are only targets.
FIA inventories are extensive inventories that provide reliable estimates for large areas. As data are subdivided into smaller and smaller areas, such as a geographic unit or a county, the sampling errors increase and the reliability of the estimates goes down.
• A State with 5 million acres of timberland would have a maximum allowable sampling error of 1.3 percent (3% x (1,000,000) 0.5 / (5,000,000) 0.5 ). • A geographic unit within that State with 1 million acres of timberland would have a 3.0 percent maximum allowable sampling error (3% x (1,000,000) 0.5 / (1,000,000) 0.5 ). • A county within that State with 100 thousand acres would have a 9.5 percent maximum allowable sampling error (3% x (1,000,000) 0.5 / (100,000) 0.5 ) at the 67 percent confidence level.
The greater allowance for sampling error in smaller areas reflects the decrease in sample size as estimation area decreases.
Estimation procedures and the calculation of confidence intervals for typical FIA tables are discussed in chapter 4. Additional information on estimation and confidence intervals can be found in Bechtold and Patterson (2005).

Chapter 3 --Database Structure
This chapter provides information about the database tables, including detailed descriptions of all attributes within the tables. Each column or attribute in a table is listed with its unabbreviated name, followed by a description of the attribute. Attributes that are coded include a list of the codes and their meanings. Appendix A is an index of the attributes, sorted alphabetically by column name, showing the table where the column is found including the attribute number in the table. Some overview information is presented below, followed by a section with complete information about all tables and attributes.

Table Descriptions
There are nineteen data tables and eleven reference tables in the Phase 1 and Phase 2 portions of the FIA Database.
• SURVEY  • COND table -Provides information on the discrete combination of landscape attributes that define the condition (a condition will have the same land class, reserved status, owner group, forest type, stand-size class, regeneration status, and stand density).  This table retains valuable information for generating biomass estimates that match earlier published reports. o TREE.CN = TREE_REGIONAL_BIOMASS.TRE_CN links a tree regional biomass record to the corresponding unique tree. • POP_ESTN_UNIT table -An estimation unit is a geographic area that can be drawn on a map. It has known area and the sampling intensity must be the same within a stratum within an estimation unit. Generally estimation units are contiguous areas, but exceptions are made when certain ownerships, usually National Forests, are sampled at different intensities. One record in the POP_ESTN_UNIT table corresponds to a single estimation unit. o POP_ESTN_UNIT.CN = POP_STRATUM.ESTN_UNIT_CN links the unique stratified geographical area (ESTN_UNIT) to the strata (STRATUMCD) that are assigned to each ESTN_UNIT. • POP_EVAL table -An evaluation is the combination of a set of plots (the sample) and a set of Phase 1 data (obtained through remote sensing, called a stratification) that can be used to produce population estimates for a State (an evaluation may be created to produce population estimates for a region other than a State, such as the Black Hills National Forest).
A record in the POP_EVAL table identifies one evaluation and provides some descriptive information about how the evaluation may be used. o POP_ESTN_UNIT.EVAL_CN = POP_EVAL.CN links the unique evaluation identifier (EVALID) in the POP_EVAL table to the unique geographical areas (ESTN_UNIT) that are stratified. Within a population evaluation (EVALID) there can be multiple population estimation units, or geographic areas across which there are a number of values being estimated (e.g., estimation of volume across counties for a given State.) • POP_EVAL_ATTRIBUTE table -Provides information as to which population estimates can be provided by an evaluation. If an evaluation can produce 22 of the 92 currently supported population estimates, there will be 22 records in the POP_EVAL_ATTRIBUTE table (one per population estimate) for that evaluation. o POP_EVAL.CN = POP_EVAL_ATTRIBUTE.EVAL_CN links the unique evaluation identifier to the list of population estimates that can be derived for that evaluation. • POP_EVAL_GRP table -Provides information on the suite of evaluations that were used to generate a complete set of reports for an inventory. In a typical State inventory report, one evaluation is used to generate an estimate of the total land area; a second evaluation is used to generate current estimates of volume, numbers of trees and biomass; and a third evaluation is used for estimating growth, removals and mortality. One record in the POP_EVAL_GRP record identifies all the evaluations that were used in generating estimates for a State inventory report. Each record in the POP_EVAL table corresponds to an EVAL_CN_FOR_XX column in the POP_EVAL_GRP table, (XX is one of the following: Expall, Expcurr, Expvol, Expgrow, Expmort, or Expremv). Similar information is contained in the POP_EVAL_TYP table, which has been added to this version of the database. o POP_EVAL_TYP.EVAL_GRP_CN = POP_EVAL_GRP.CN links the evaluation type record to the evaluation group record. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPALL links the evaluation for all land to the evaluation identifier that includes all plots used to make the estimate. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPCURR links the evaluation for sampled land to the evaluation identifier that includes all sampled plots used to make the estimate. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPVOL links the evaluation for tree volume, biomass, or number of trees to the evaluation identifier that includes all plots used to make these estimates. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPGROW links the evaluation for average annual tree growth to the evaluation identifier that includes all remeasured plots used to make the estimate. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPMORT links the evaluation for average annual tree mortality to the evaluation identifier that includes all remeasured plots used to make the estimate. o POP_EVAL.CN = POP_EVAL_GRP.EVAL_CN_FOR_EXPREMV links the evaluation for average annual tree removals to the evaluation identifier that includes all remeasured plots used to make the estimate. • POP_EVAL_TYP table -Provides information on the type of evaluations that were used to generate a set of tables for an inventory report. In a typical State inventory report, one evaluation is used to generate an estimate of the total land area; a second evaluation is used to generate current estimates of volume, numbers of trees and biomass; and a third evaluation is used for estimating growth, removals and mortality.    Tables   Each summarized table in chapter 3 has a list of keys just below the bottom of the table. These keys are used to join data from different tables. The following provides a general definition of each kind of key.  Table name  Table abbreviation  SURVEY  SRV  COUNTY  CTY  PLOT  PLT  COND  CND  SUBPLOT  SBP  SUBP_COND  SCD  TREE  TRE  SEEDLING  SDL  SITETREE  SIT  BOUNDARY  BND  SUBP_COND_CHNG_MTRX  CMX  TREE_REGIONAL_BIOMASS  TRB  POP_ESTN_UNIT  PEU  POP_EVAL  PEV  POP_EVAL_ATTRIBUTE  PEA  POP_EVAL_GRP  PEG  POP_EVAL_TYP  PET  POP_PLOT_STRATUM_ASSGN  PPSA  POP_STRATUM  PSM  REF_POP_ATTRIBUTE  PAE  REF_POP_EVAL_TYP_DESCR  PED  REF_FOREST_TYPE  RFT  REF_SPECIES  SPC  REF_SPECIES_GROUP  SPG  REF_HABTYP_DESCRIPTION  RHN  REF_HABTYP_PUBLICATION  RPN  REF_CITATION  CIT  REF_FIADB_VERSION  RFN  REF_STATE_ELEV  RSE  REF_UNIT  UNT  Unique key  Multiple columns in a table whose values uniquely identify each row in an Oracle table.  There can be one and only one row for each unique key value.   The unique key varies for each FIADB 4.0 table. The unique key for the PLOT table is  STATECD, INVYR, UNITCD, COUNTYCD, and PLOT. The unique key for the COND  table is  INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.

Primary key
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system 3. P3_OZONE_IND Phase 3 ozone indicator. Values are Y (yes) and N (no). If Y, then the Survey is for a P3 ozone inventory. If N, then the Survey is not for a P3 ozone inventory. Note that P3_OZONE_IND is part of the unique key because ozone data are stored as a separate inventory (survey); therefore, combinations of STATECD and INVYR may occur more than one time.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
16. CYCLE Inventory cycle number. A number assigned to a set of plots, measured over a particular period of time from which a State estimate using all possible plots is obtained. A cycle number >1 does not necessarily mean that information for previous cycles resides in the database. A cycle is relevant for periodic and annual inventories.
17. SUBCYCLE Inventory subcycle number. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process.
County Table (Oracle table name

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
Plot Table (Oracle table name  INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005. INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system

PLOT_NONSAMPLE_REASN_CD
Plot nonsampled reason code. For entire plots that cannot be sampled, one of the following reasons is recorded.

Code Description 01
Outside U.S. boundary -Entire plot is outside of the U.S. border. 02 Denied access area -Access to the entire plot is denied by the legal owner, or by the owner of the only reasonable route to the plot. 03 Hazardous -Entire plot cannot be accessed because of a hazard or danger, for example cliffs, quarries, strip mines, illegal substance plantations, high water, etc. 05 Lost data -Plot data file was discovered to be corrupt after a panel was completed and submitted for processing. 06 Lost plot -Entire plot cannot be found. 07 Wrong location -Previous plot can be found, but its placement is beyond the tolerance limits for plot location. 08 Skipped visit -Entire plot skipped. Used for plots that are not completed prior to the time a panel is finished and submitted for processing. This code is for office use only. 09 Dropped intensified plot -Intensified plot dropped due to a change in grid density. This code used only by units engaged in intensification. This code is for office use only. 10 Other -Entire plot not sampled due to a reason other than one of the specific reasons already listed. 11 Ocean -Plot falls in ocean water below mean high tide line. 18. RDDISTCD Horizontal distance to improved road code. The straight-line distance from plot center to the nearest improved road, which is a road of any width that is maintained as evidenced by pavement, gravel, grading, ditching, and/or other improvements. Populated for all forested plots using the National Field Guide protocols (MANUAL ≥1.0) and populated by some FIA work units for inventory plots collected where MANUAL <1.0.
19. WATERCD Water on plot code. Water body <1 acre in size or a stream <30 feet wide that has the greatest impact on the area within the forest land portion of the four subplots. The coding hierarchy is listed in order from large permanent water to temporary water. Populated for all forested plots using the National Field Guide protocols (MANUAL ≥1.0) and populated by some FIA work units for inventory plots collected where MANUAL <1.0.
Code Description 0 None -no water sources within the accessible forest land condition class 1 Permanent streams or ponds too small to qualify as noncensus water 2 Permanent water in the form of deep swamps, bogs, marshes without standing trees present and less than 1.0 acre in size, or with standing trees 3 Ditch/canal -human-made channels used as a means of moving water, e.g., for irrigation or drainage, which are too small to qualify as noncensus water 4 Temporary streams 5 Flood zones -evidence of flooding when bodies of water exceed their natural banks 9 Other temporary water -specified in plot-level notes.
20. LAT Latitude. The approximate latitude of the plot in decimal degrees using NAD 83 datum. Actual plot coordinates cannot be released because of a Privacy provision enacted by Congress in the Food Security Act of 1985. Therefore, this attribute is approximately +/-1 mile and, for annual inventory data, most plots are within +/-½ mile. Annual data have additional uncertainty for private plots caused by swapping plot coordinates for up to 20 percent of the plots. In some cases, the county centroid is used when the actual coordinate is not available.

LON
Longitude. The approximate longitude of the plot in decimal degrees using NAD 83 datum. Actual plot coordinates cannot be released because of a Privacy provision enacted by Congress in the Food Security Act of 1985. Therefore, this attribute is approximately +/-1 mile and, for annual inventory data, most plots are within +/-½ mile. Annual data have additional uncertainty for private plots caused by swapping plot coordinates for up to 20 percent of the plots. In some cases, the county centroid is used when the actual coordinate is not available.
22. ELEV Elevation. The distance the plot is located above sea level, recorded in feet (NAD 83 datum). Negative values indicate distance below sea level.

GROW_TYP_CD
Type of annual volume growth code. A code indicating how volume growth is estimated. Current annual growth is an estimate of the amount of volume that was added to a tree in the year before the tree was sampled, and is based on the measured diameter increment recorded when the tree was sampled or on a modeled diameter for the previous year. Periodic annual growth is an estimate of the average annual change in volume occurring between two measurements, usually the current inventory and the previous inventory, where the same plot is evaluated twice. Periodic annual growth is the increase in volume between inventories divided by the number of years between each inventory. This attribute is blank (null) if the plot does not contribute to the growth estimate.

Code Description 1
Current annual 2 Periodic annual

MORT_TYP_CD
Type of annual mortality volume code. A code indicating how mortality volume is estimated. Current annual mortality is an estimate of the volume of trees dying in the year before the plot was measured, and is based on the year of death or on a modeled estimate. Periodic annual mortality is an estimate of the average annual volume of trees dying between two measurements, usually the current inventory and previous inventory, where the same plot is evaluated twice. Periodic annual mortality is the loss of volume between inventories divided by the number of years between each inventory. Periodic average annual mortality is the most common type of annual mortality estimated. This attribute is blank (null) if the plot does not contribute to the mortality estimate.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

MICROPLOT_LOC
Microplot location. Values are 'OFFSET' or 'CENTER.' The offset microplot center is located 12 feet due east (90 degrees) of subplot center. The current standard is that the microplot is located in the 'OFFSET' location, but some earlier inventories, including some early panels of the annual inventory, may contain data where the microplot was located at the 'CENTER' location. Populated for annual inventory and may be populated for periodic inventory.

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system 8. CONDID Condition class number. Unique identifying number assigned to each condition on a plot. A condition is initially defined by condition class status. Differences in reserved status, owner group, forest type, stand-size class, regeneration status, and stand density further define condition for forest land.
Mapped nonforest conditions are also assigned numbers. At the time of the plot establishment, the condition class at plot center (the center of subplot 1) is usually designated as condition class 1. Other condition classes are assigned numbers sequentially at the time each condition class is delineated. On a plot, each sampled condition class must have a unique number that can change at remeasurement to reflect new conditions on the plot.

COND_STATUS_CD
Condition status code. A code indicating the basic land cover.

Code Description 1
Forest land -Land with at least 10 percent cover (or equivalent stocking) by live trees of any size, including land that formerly had such tree cover and that will be naturally or artificially regenerated. To qualify, the area must be at least 1.0 acre in size and 120.0 feet wide. Forest land includes transition zones, such as areas between forest and nonforest lands that have at least 10 percent cover (or equivalent stocking) with live trees and forest areas adjacent to urban and built-up lands. Roadside, streamside, and shelterbelt strips of trees must have a width of at least 120 feet and continuous length of at least 363 feet to qualify as forest land. Unimproved roads and trails, streams, and clearings in forest areas are classified as forest if they are <120 feet wide or an acre in size. Treecovered areas in agricultural production settings, such as fruit orchards, or treecovered areas in urban settings, such as city parks, are not considered forest land. For data collected prior to annual inventory (PLOT.MANUAL <1.0), the definition for forest land may have been slightly different (for example, in the past some FIA work units used 5 percent cover rather than 10 percent.) 2 Nonforest land -Any land within the sample that does not meet the definition of accessible forest land or any of the other types of basic land covers. To qualify, the area must be at least 1.0 acre in size and 120.0 feet wide, with some exceptions that are described in the document "Forest inventory and analysis national core field guide, volume 1: field data collection procedures for Phase 2 plots, version 4.0." (http://www.fia.fs.fed.us/library/field-guides-methodsproc/.) Evidence of "possible" or future development or conversion is not considered. A nonforest land condition will remain in the sample and will be examined at the next occasion to see if it has become forest land. 3 Noncensus water -Lakes, reservoirs, ponds, and similar bodies of water 1.0 acre to 4.5 acre in size. Rivers, streams, canals, etc., 30.0 feet to 200 feet wide (1990 U.S. Census definition -U.S. Census Bureau 1994). This definition was used in the 1990 census and applied when the data became available. Earlier inventories defined noncensus water differently.

Code Description 4
Census water -Lakes, reservoirs, ponds, and similar bodies of water 4.5 acre in size and larger; and rivers, streams, canals, etc., more than 200 feet wide (1990 U.S. Census definition; U.S. Census Bureau 1994). 5 Nonsampled -Any portion of a plot within accessible forest land that cannot be sampled is delineated as a separate condition. There is no minimum size requirement. The reason the condition was not sampled is provided in COND_NONSAMPLE_REASN_CD.

COND_NONSAMPLE_REASN_CD
Condition nonsampled reason code. For condition classes that cannot be sampled, one of the following reasons is recorded.

Code Description 01
Outside U.S. boundary -Condition class is outside the U.S. border. 02 Denied access area -Access to the condition class is denied by the legal owner, or by the owner of the only reasonable route to the condition class. 03 Hazardous situation -Condition class cannot be accessed because of a hazard or danger, for example cliffs, quarries, strip mines, illegal substance plantations, temporary high water, etc. 05 Lost data -The data file was discovered to be corrupt after a panel was completed and submitted for processing. Used for the single condition that is required for this plot. This code is for office use only. 06 Lost plot -Entire plot cannot be found. Used for the single condition that is required for this plot. 07 Wrong location -Previous plot can be found, but its placement is beyond the tolerance limits for plot location. Used for the single condition that is required for this plot. 08 Skipped visit -Entire plot skipped. Used for plots that are not completed prior to the time a panel is finished and submitted for processing. Used for the single condition that is required for this plot. This code is for office use only. 09 Dropped intensified plot -Intensified plot dropped due to a change in grid density. Used for the single condition that is required for this plot. This code used only by units engaged in intensification. This code is for office use only. 10 Other -Condition class not sampled due to a reason other than one of the specific reasons listed. 11 Ocean -Condition falls in ocean water below mean high tide line.
11. RESERVCD Reserved status code. (Core for accessible forestland; Core optional for other sampled land.) Reserved land is land that is withdrawn by law(s) prohibiting the management of the land for the production of wood products. Other federal (OWNCD 21,22,23,24,25) 30 State and local government (OWNCD 31, 32, 33) 40 Private (OWNCD 41,42,43,44,45,46) 14. FORINDCD Private owner industrial status code. (Core for all accessible forestland where owner group is private; Core optional for other sampled land where owner group is private.) A code indicating whether the landowner owns and operates a primary wood processing plant. A primary wood processing plant is any commercial operation that originates the primary processing of wood on a regular and continuing basis. Examples include: pulp or paper mill, sawmill, panel board mill, post or pole mill.
This attribute is retained in this database for informational purposes but is intentionally left blank (null) because of the FIA data confidentiality policy.
Users needing this type of information should contact the FIA Spatial Data Services (SDS) group by following the instructions provided at: http://www.fia.fs.fed.us/tools-data/spatial/.
Code Description 0 Land is not owned by industrial owner with wood processing plant 1 Land is owned by industrial owner with wood processing plant 15. ADFORCD Administrative forest code. Identifies the administrative unit (Forest Service Region and National Forest) in which the condition is located. The first two digits of the four digit code are for the region number and the last two digits are for the Administrative National Forest number. Refer to appendix E for codes. Populated only for U.S. Forest Service lands OWNGRPCD = 10 and blank (null) for all other owners.
16. FORTYPCD Forest type code. This is the forest type used for reporting purposes. It is primarily derived using a computer algorithm, except when less than 25 percent of the plot samples a particular forest condition.
Usually, FORTYPCD equals FORTYPCDCALC. In certain situations, however, the result from the algorithm (FORTYPCDCALC) is overridden by the field call. The field-recorded forest type code (FLDTYPCD) is stored in this attribute when less than 25 percent of the plot samples the forested condition (CONDPROP_UNADJ <0.25).
In most cases, FORTYPCD is the same as the field-recorded forest type (FLDTYPCD). However, situations of under sampling may cause this attribute to differ from FLDTYPCD.
Nonstocked forest land is land that currently has less than 10 percent stocking but formerly met the definition of forest land. Forest conditions meeting this definition have few, if any, trees sampled. In these instances, the algorithm cannot assign a specific forest type and the resulting forest type code is 999, meaning nonstocked.
Refer to appendix D for the complete list of forest type codes and names.
17. FLDTYPCD Field forest type code. Forest type, assigned by the field crew, based on the tree species or species groups forming a plurality of all live stocking. The field crew assesses the forest type based on the acre of forestland around the plot, in addition to the species sampled on the condition. Refer to appendix D for a detailed list of forest type codes and names. Nonstocked forest land is land that currently has less than 10 percent stocking but formerly met the definition of forest land. When PLOT.MANUAL <2.0, forest conditions that do not meet this stocking level were coded FLDTYPCD = 999. Beginning with manual version 2.0, the crew no longer recorded nonstocked as 999. Instead, they recorded FLDSZCD = 0 to identify nonstocked conditions and entered an estimated forest type for the condition. The crew determined the estimated forest type by either recording the previous forest type on remeasured plots or, on all other plots, the most appropriate forest type to the condition based on the seedlings present or the forest type of the adjacent forest stands. Periodic inventories will differ in the way FLDTYPCD was recorded -it is best to check with individual FIA work units for details. In general, when FLDTYPCD is used for analysis, it is necessary to examine the values of both FLDTYPCD and FLDSZCD to identify nonstocked forest land.
18. MAPDEN Mapping density. A code indicating the relative tree density of the condition. Codes other than 1 are used as an indication that a significant difference in tree density is the only factor causing another condition to be recognized and mapped on the plot. May be blank (null) for periodic inventories.
Code Description 1 Initial tree density class 2 Density class 2 -density different than density of the condition assigned a tree density class of 1 3 Density class 3 -density different than densities of the conditions assigned tree density classes of 1 and 2 19. STDAGE Stand age. For annual inventories (PLOT.MANUAL ≥1.0), stand age is equal to the field-recorded stand age (FLDAGE) with some exceptions. One exception is if FLDAGE = 999, then stand age is computed. When FLDAGE = 998, STDAGE is blank (null) because no trees were cored in the field. Another exception is that RMRS always computes stand age using fieldrecorded tree ages from trees in the calculated stand-size class. If no tree ages are available, then RMRS sets this attribute equal to FLDAGE. For all inventories, nonstocked stands have STDAGE set to 0. In periodic inventories, stand age is determined using local procedures. Annual inventory data will contain stand ages assigned to the nearest year. For some older inventories, stand age was set to 10-year classes for stands <100 years old, 20-year age classes for stands between 100 and 200 years, and 100-year age classes if older than 200 years. These classes were converted to store the midpoint of the age class in years. Blank (null) values in the periodic data (PLOT.MANUAL <1.0) indicate that the stand was recorded as mixed age on forested condition classes. Age is difficult to measure and therefore STDAGE may have large measurement errors.
20. STDSZCD Stand-size class code. A classification of the predominant (based on stocking) diameter class of live trees within the condition assigned using an algorithm. Large diameter trees are at least 11.0 inches diameter for hardwoods and at least 9.0 inches diameter for softwoods. Medium diameter trees are at least 5.0 inches diameter and smaller than large diameter trees. Small diameter trees are <5.0 inches diameter. When <25 percent of the plot samples the forested condition (CONDPROP_UNADJ <0.25), this attribute is set to the equivalent field-recorded stand-size class (FLDSZCD). Populated for all forest annual plots, all forest periodic plots, and all NCRS periodic plots that were measured as "nonforest with trees" (e.g., wooded pasture, windbreaks).

Code Description 1
Large diameter -Stands with an all live stocking of at least 10 (base 100); with more than 50 percent of the stocking in medium and large diameter trees; and with the stocking of large diameter trees equal to or greater than the stocking of medium diameter trees 2 Medium diameter -Stands with an all live stocking of at least 10 (base 100); with more than 50 percent of the stocking in medium and large diameter trees; and with the stocking of large diameter trees less than the stocking of medium diameter trees 3 Small diameter -Stands with an all live stocking value of at least 10 (base 100) on which at least 50 percent of the stocking is in small diameter trees 5 Nonstocked -Forest land with all live stocking <10 21. FLDSZCD Field stand-size class code. Field-assigned classification of the predominant (based on stocking) diameter class of live trees within the condition. Blank (null) values may be present for periodic inventories.
Code Description 0 Nonstocked -Meeting the definition of accessible land and one of the following applies (1) <10 percent stocked by trees of any size, and not classified as cover trees (see code 6), or (2) for several western woodland species where stocking standards are not available, <5 percent crown cover of trees of any size. 1 ≤4.9 inches (seedlings / saplings). At least 10 percent stocking (or 5 percent crown cover if stocking standards are not available) in trees of any size; and at least 2/3 of the crown cover is in trees <5.0 inches DBH/DRC. 2 5.0 -8.9 inches (softwoods)/ 5.0 -10.9 inches (hardwoods). At least 10 percent stocking (or 5 percent crown cover if stocking standards are not available) in trees of any size; and at least one-third of the crown cover is in trees ≥5.0 inches DBH/DRC and the plurality of the crown cover is in softwoods 5.0 -8.9 inches diameter and/or hardwoods 5.0 -10.9 inches DBH, and/or for western woodland trees 5.0 -8.9 inches DRC. 3 9.0 -19.9 inches (softwoods)/ 11.0 -19.9 inches (hardwoods). At least 10 percent stocking (or 5 percent crown cover if stocking standards are not available) in trees of any size; and at least one-third of the crown cover is in trees ≥5.0 inches DBH/DRC and the plurality of the crown cover is in softwoods 9.0 -19.9 inches diameter and/or hardwoods between 11.0 -19.9 inches DBH, and for western woodland trees 9.0 -19.9 inches DRC. 4 20.0 -39.9 inches. At least 10 percent stocking (or 5 percent crown cover if stocking standards are not available) in trees of any size; and at least onethird of the crown cover is in trees ≥5.0 inches DBH/DRC and the plurality of the crown cover is in trees 20.0 -39.9 inches DBH. 5 40.0+ inches. At least 10 percent stocking (or 5 percent crown cover if stocking standards are not available) in trees of any size; and at least onethird of the crown cover is in trees ≥5.0 inches DBH/DRC and the plurality of the crown cover is in trees ≥40.0 inches DBH. 6 Cover trees (trees not on species list, used for plots classified as nonforest): <10 percent stocking by trees of any size, and >5 percent crown cover of species that comprise cover trees.

SITECLCD
Site productivity class code. A classification of forest land in terms of inherent capacity to grow crops of industrial wood. Identifies the potential growth in cubic feet/acre/year and is based on the culmination of mean annual increment of fully stocked natural stands. For data stored in the database that were processed outside of NIMS, this variable may be assigned based on the site productivity determined with the site trees, or from some other source, but the actual source of the site productivity class code is not known. For data processed with NIMS, this variable may either be assigned based on the site trees available for the plot, or, if no valid site trees are available, this variable is set equal to SITECLCDEST, a default value that is either an estimated or predicted site productivity class. If SITECLCDEST is used to populate SITECLCD, the variable SITECL_METHOD is set to 6.

PROP_BASIS Proportion basis.
A value indicating what type of fixed-size subplots were installed when this plot was sampled. This information is needed to use the proper adjustment factor for the stratum in which the plot occurs (see POP_STRATUM.ADJ_FACTOR_SUBP and POP_STRATUM.ADJ_FACTOR_MACR.) Usually 24-foot radius subplots are installed and in this case, the value for PROP_BASIS is "SUBP." However, when 58.9-foot radius macroplots are installed, the value is "MACR." This attribute is blank (null) for periodic inventories.

CONDPROP_UNADJ
Condition proportion unadjusted. The unadjusted proportion of the plot that is in the condition. This variable is retained for ease of area calculations. It is equal to either SUBPPROP_UNADJ or MACRPROP_UNADJ, depending on the value of PROP_BASIS. The sum of all condition proportions for a plot equals 1. When generating population area estimates, this proportion is adjusted by either the POP_STRATUM.ADJ_FACTOR_MACR or the POP_STRATUM.ADJ_FACTOR_SUBP to account for partially nonsampled plots (access denied or hazardous portions).

MICRPROP_UNADJ
Microplot proportion unadjusted. The unadjusted proportion of the microplots that are in the condition. The sum of all microplot condition proportions for a plot equals 1.

SUBPPROP_UNADJ
Subplot proportion unadjusted. The unadjusted proportion of the subplots that are in the condition. The sum of all subplot condition proportions for a plot equals 1.

MACRPROP_UNADJ
Macroplot proportion unadjusted. The unadjusted proportion of the macroplots that are in the condition. When macroplots are installed, the sum of all macroplot condition proportions for a plot equals 1; otherwise this attribute is left blank (null).
33. SLOPE Slope. The angle of slope, in percent, of the condition. Valid values are 000 through 155 for data collected when PLOT.MANUAL ≥1.0, and 000 through 200 on data collected when PLOT.MANUAL <1.0. When PLOT.MANUAL <1.0, the field crew measured condition slope by sighting along the average incline or decline of the condition. When PLOT.MANUAL ≥1.0, slope is collected on subplots but no longer collected for conditions. When PLOT.MANUAL ≥1.0, the slope from the subplot representing the greatest percentage of the condition is assigned as a surrogate. In the event that two or more subplots represent the same amount of area in the condition, the slope from the lower numbered subplot is used. Populated for all forest annual plots, all forest periodic plots, and all NCRS periodic plots that were measured as "nonforest with trees" (e.g., wooded pasture, windbreaks).
34. ASPECT Aspect. The direction of slope, to the nearest degree, for most of the condition. North is recorded as 360. When slope is <5 percent, there is no aspect and this item is set to zero. When PLOT.MANUAL <1.0, the field crew measured condition aspect. When PLOT.MANUAL ≥1.0, aspect is collected on subplots but no longer collected for conditions. NOTE: for plots measured when PLOT.MANUAL ≥1.0, the aspect from the subplot representing the greatest percentage of the condition is assigned as a surrogate. In the event that two or more subplots represent the same percentage of area in the condition, the slope from the lower numbered subplot is used. Populated for all forest annual plots, all forest periodic plots, and all NCRS periodic plots that were measured as "nonforest with trees" (e.g., wooded pasture, windbreaks).

PHYSCLCD
Physiographic class code. The general effect of land form, topographical position, and soil on moisture available to trees. These codes are new in annual inventory; older inventories have been updated to these codes when possible. Also populated for the NCRS periodic plots that were measured as "nonforest with trees" (e.g., wooded pasture, windbreaks).

Code Description
Xeric sites (normally low or deficient in available moisture) 11 Dry Tops -Ridge tops with thin rock outcrops and considerable exposure to sun and wind. 12 Dry Slopes -Slopes with thin rock outcrops and considerable exposure to sun and wind. Includes most mountain/steep slopes with a southern or western exposure. 13 Deep Sands -Sites with a deep, sandy surface subject to rapid loss of moisture following precipitation. Typical examples include sand hills, ridges, and flats in the South, sites along the beach and shores of lakes and streams. 19 Other Xeric -All dry physiographic sites not described above.
Mesic sites (normally moderate but adequate available moisture) 21 Flatwoods -Flat or fairly level sites outside of flood plains. Excludes deep sands and wet, swampy sites. 22 Rolling Uplands -Hills and gently rolling, undulating terrain and associated small streams. Excludes deep sands, all hydric sites, and streams with associated flood plains. 23 Moist Slopes and Coves -Moist slopes and coves with relatively deep, fertile soils. Often these sites have a northern or eastern exposure and are partially shielded from wind and sun. Includes moist mountain tops and saddles. 24 Narrow flood plains/Bottomlands -Flood plains and bottomlands less than 1/4-mile in width along rivers and streams. These sites are normally well drained but are subjected to occasional flooding during periods of heavy or extended precipitation. Includes associated levees, benches, and terraces within a 1/4 mile limit. Excludes swamps, sloughs, and bogs.

Code Description 25
Broad Floodplains/Bottomlands -Floodplains and bottomlands ¼ mile or wider along rivers and streams. These sites are normally well drained but are subjected to occasional flooding during periods of heavy or extended precipitation. Includes associated levees, benches, and terraces. Excludes swamps, sloughs, and bogs with year-round water problems. 29 Other Mesic -All moderately moist physiographic sites not described above.
Hydric sites (normally abundant or overabundant moisture all year) 31 Swamps/Bogs -Low, wet, flat, forested areas usually quite extensive that are flooded for long periods except during periods of extreme drought. Excludes cypress ponds and small drains. 32 Small Drains -Narrow, stream-like, wet strands of forest land often without a well-defined stream channel. These areas are poorly drained or flooded throughout most of the year and drain the adjacent higher ground. 33 Bays and wet pocosins -Low, wet, boggy sites characterized by peaty or organic soils. May be somewhat dry during periods of extended drought. Examples include sites in the Carolina bays in the Southeast United States. 34 Beaver ponds. 35 Cypress ponds. 39 Other hydric -All other hydric physiographic sites.

GSSTKCD
Growing-stock stocking code. A code indicating the stocking of the condition by growing-stock trees, including seedlings. Growing-stock trees are those where tree class (TREE.TREECLCD) equals 2 or, for seedlings that do not have tree class assigned where species group (TREE.SPGRPCD) is not equal to 23 (western woodland softwoods), 43 (eastern noncommercial hardwoods), and 48 (western woodland hardwoods). Populated for all forest annual plots, all forest periodic plots, and all NCRS periodic plots that were measured as "nonforest with trees" (e.g., wooded pasture, windbreaks).

Code Description
Fully stocked (60 -99%) 3 Medium stocked (35 -59%) 4 Poorly stocked (10 -34%) 5 Nonstocked (  Cutting -The removal of one or more trees from a stand. 20 Site preparation -Clearing, slash burning, chopping, disking, bedding, or other practices clearly intended to prepare a site for either natural or artificial regeneration. 30 Artificial regeneration -Following a disturbance or treatment (usually cutting), a new stand where at least 50 percent of the live trees present resulted from planting or direct seeding. 40 Natural regeneration -Following a disturbance or treatment (usually cutting), a new stand where at least 50 percent of the live trees present (of any size) were established through the growth of existing trees and/or natural seeding or sprouting. 50 Other silvicultural treatment -The use of fertilizers, herbicides, girdling, pruning, or other activities (not covered by codes 10-40) designed to improve the commercial value of the residual stand, or chaining, which is a practice used on western woodlands to encourage wildlife forage. Nonforest-Chaparral* *These codes are currently regional. They will become national in PLOT.MANUAL = 5.0.

BALIVE
Basal area of live trees. Basal area in square feet per acre of all live trees over 1 inch DBH/DRC sampled in the condition.
52. FLDAGE Field-recorded stand age. The stand age as assigned by the field crew. Based on the average total age, to the nearest year, of the trees in the field-recorded stand-size class of the condition, determined using local procedures. For nonstocked stands, 0 is stored. If all of the trees in a condition class are of a species that by regional standards cannot be bored for age (e.g., mountain mahogany, tupelo), 998 is recorded. If tree cores are not counted in the field, but are collected and sent to the office for the counting of rings, 999 is recorded.

ALSTK
All-live-tree stocking percent. The sum of stocking percent values of all live trees on the condition. The percent is then assigned to a stocking class, which is found in ALSTKCD. May not be populated for some FIA work units when PLOT.MANUAL <1.0.

GSSTK
Growing-stock stocking percent. The sum of stocking percent values of all growing-stock trees on the condition. The percent is then assigned to a stocking class, which is found in GSSTKCD. May not be populated for some FIA work units when PLOT.MANUAL <1.0.

FORTYPCDCALC
Forest type code calculated. Forest type is always calculated based on the tree species sampled on the condition. The forest typing algorithm is a hierarchical procedure applied to the tree species sampled on the condition. The algorithm begins by comparing the live tree stocking of softwoods and hardwoods and continues in a stepwise fashion comparing successively smaller subgroups of the preceding aggregation of initial type groups, selecting the group with the largest aggregate stocking value. The comparison proceeds in most cases until a plurality of a forest type is identified.
Nonstocked forest land is land that currently has less than 10 percent stocking but formerly met the definition of forest land. Forest conditions meeting this definition have few, if any, trees sampled. In these instances, the algorithm cannot assign a specific forest type and the resulting forest type code is 999, meaning nonstocked. See also FORTYPCD and FLDTYPCD for other forest type attributes. Refer to appendix D for a complete list of forest type codes and names.

SITECLCDEST
Site productivity class code estimated. This is a field-recorded code that is an estimated or predicted indicator of site productivity. It is used as the value for SITECLCD if no valid site tree is available. When SITECLCDEST is used as SITECLCD, SITECL_METHOD is set to 6. For data stored in the database that were processed prior to the use of NIMS, this variable is blank (null). Only collected by certain FIA work units (SURVEY.RSCD = 24, 26, 27 or 33). Site index or site productivity class estimated either in the field or office. 4 Site index or site productivity class estimated by the height intercept method during this inventory. 5 Site index or site productivity class estimated using multiple site trees. 6 Site index or site productivity class estimated using default values.

CARBON_DOWN_DEAD
Carbon in down dead. Carbon (tons per acre) of woody material >3 inches in diameter on the ground, and stumps and their roots >3 inches in diameter. Estimated from models based on geographic area, forest type, and live tree carbon density . This modeled attribute is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table.

CARBON_LITTER
Carbon in litter. Carbon (tons per acre) of organic material on the floor of the forest, including fine woody debris, humus, and fine roots in the organic forest floor layer above mineral soil. Estimated from models based on geographic area, forest type, and (except for nonstocked and pinyon-juniper stands) stand age (Smith and Heath 2002). This modeled attribute is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table.

CARBON_SOIL_ORG
Carbon in organic soil. Carbon (tons per acre) in fine organic material below the soil surface to a depth of 1 meter. Does not include roots. Estimated from models based on geographic area and forest type . This modeled attribute is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table.

CARBON_STANDING_DEAD
Carbon in standing dead. Carbon (tons per acre) in standing dead trees, including coarse roots, is estimated from models based on geographic area, forest type, and (except for nonstocked stands) growing stock volume . This modeled variable is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. For most users it is preferable to calculate carbon (tons per acre) for annual inventories from the Phase 2 tree data. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table.

CARBON_UNDERSTORY_AG
Carbon in understory aboveground. Carbon (tons per acre) in the aboveground portions of seedlings, shrubs, and bushes. Estimated from models based on geographic area, forest type, and (except for nonstocked and pinyon-juniper stands) live tree carbon density (Smith and Health 2008). This modeled attribute is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table.

CARBON_UNDERSTORY_BG
Carbon in understory belowground. Carbon (tons per acre) in the belowground portions of seedlings, shrubs, and bushes. Estimated from models based on geographic area, forest type, and (except for nonstocked and pinyon-juniper stands) live tree carbon density . This modeled attribute is a component of the EPA's Greenhouse Gas Inventory and is not a direct sum of Phase 2 or Phase 3 measurements. This is a per acre estimate and must be multiplied by the appropriate expansion and condition proportion adjustment factor located in the POP_STRATUM table. 73. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
79. CYCLE Inventory cycle number. A number assigned to a set of plots, measured over a particular period of time from which a State estimate using all possible plots is obtained. A cycle number >1 does not necessarily mean that information for previous cycles resides in the database. A cycle is relevant for periodic and annual inventories.
80. SUBCYCLE Inventory subcycle number. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process.

SOIL_ROOTING_DEPTH_PNW
Soil rooting depth, Pacific Northwest Research Station. Describes the soil depth (the depth to which tree roots can penetrate) within each forest land condition class. Required for all forest condition classes. This variable is coded 1 when more than half of area in the condition class is estimated to be ≤20 inches deep. Ground pumice, decomposed granite, and sand all qualify as types of soil. Only collected by certain FIA work units (SURVEY.RSCD = 26).
Code Description 1 ≤20 inches 2 >20 inches 82. GROUND_LAND_CLASS_PNW Present ground land class, Pacific Northwest Research Station. A refinement of forest land that distinguishes timberland and a variety of forest land types. Each code, and corresponding ground land class (GLC) name and description are listed. Only collected by certain FIA work units (SURVEY.RSCD = 26).

Code Description 120
Timberland -Forest land that is potentially capable of producing at least 20 cubic feet/acre/year at culmination in fully stocked, natural stands (1.4 cubic meters/hectare/year) of continuous crops of trees to industrial roundwood size and quality. Industrial roundwood requires species that grow to size and quality adequate to produce lumber and other manufactured products (exclude fence posts and fuel wood that are not considered manufactured). Timberland is characterized by no severe limitations on artificial or natural restocking with species capable of producing industrial roundwood.

Code Description 141
Other forest rocky -Other forest land that can produce tree species of industrial roundwood size and quality, but that is unmanageable because the site is steep, hazardous, and rocky, or is predominantly nonstockable rock or bedrock, with trees growing in cracks and pockets. Other forest-rocky sites may be incapable of growing continuous crops due to inability to obtain adequate regeneration success. 142 Other forest unsuitable site (wetland, subalpine, or coastal conifer scrub; California only) -Other forest land that is unsuited for growing industrial roundwood because of one of the following environment factors: willow bogs, spruce bogs, sites with high water tables or even standing water for a portion of the year, and harsh sites due to extreme climatic and soil conditions. Trees present are often extremely slow growing and deformed. Examples: whitebark pine, lodgepole, or mountain hemlock stands at timberline; shore pine along the sparkling blue Pacific Ocean (Monterey, Bishop, and Douglas-fir); willow wetlands with occasional cottonwoods present; Sitka spruce-shrub communities bordering tidal flats and channels along the coast. Includes aspen stands in highdesert areas or areas where juniper/mountain mahogany are the predominant species. 143 Other forest pinyon-juniper -Areas currently capable of 10 percent or more tree stocking with forest trees, with juniper species predominating. These areas are not now, and show no evidence of ever having been,10 percent or more stocked with trees of industrial roundwood form and quality. Stocking capabilities indicated by live juniper trees or juniper stumps and juniper snags less than 25 years dead or cut. Ten percent juniper stocking means 10 percent crown cover at stand maturity. For western woodland juniper species, ten percent stocking means 5 percent crown cover at stand maturity. 144 Other forest-oak (formally oak woodland) -Areas currently 10 percent or more stocked with forest trees, with low quality forest trees of oak, gray pine, madrone, or other hardwood species predominating, and that are not now, and show no evidence of ever having been, 10 percent or more stocked with trees of industrial roundwood form and quality. Trees on these sites are usually short, slow growing, gnarled, poorly formed, and generally suitable only for fuel wood. The following types are included: blue oak, white oak, live oak, oak-gray pine. 146 Other forest unsuitable site (Oregon and Washington only) -Other forest land that is unsuited for growing industrial roundwood because of one of the following environment factors: willow bogs, spruce bogs, sites with high water tables or even standing water for a portion of the year, and harsh sites due to climatic conditions. Trees present are often extremely slow growing and deformed. Examples: whitebark pine or mountain hemlock stands at timberline, shore pine along the Pacific Ocean, willow wetlands with occasional cottonwoods present, and Sitka spruce-shrub communities bordering tidal flats and channels along the coast. Aspen stands in high-desert areas or areas where juniper/mountain mahogany are the predominant species are considered other forest-unsuitable site. 148 Other forest-Cypress (California only) -Forest land with forest trees with cypress predominating. Shows no evidence of having had 10 percent or more cover of trees of industrial roundwood quality and species. 149 Other forest-Low Productivity (this code is calculated in the office) -Forestland capable of growing crops of trees to industrial roundwood quality, but not able to grow wood at the rate of 20 cubic feet/acre/year. Included are areas of low stocking potential and/or very low site index. 150 Other forest curlleaf mountain mahogany -Areas currently capable of 10 percent or more tree stocking with forest trees, with curlleaf mountain mahogany species predominating. These areas are not now, and show no evidence of ever having been, 10 percent or more stocked with trees of industrial roundwood form and quality; 10 percent mahogany stocking means 5 percent crown cover at stand maturity.

PLANT_STOCKABILITY_FACTOR_PNW
Plant stockability factor, Pacific Northwest Research Station. Some plots in PNWRS have forest land condition classes that are low site, and are incapable of attaining normal yield table levels of stocking. For such classes, potential productivity (mean annual increment at culmination) must be discounted. Most forested conditions have a default value of 1 assigned; those conditions that meet the low site criteria have a value between 0.1 and 1. Key plant indicators and plant communities are used to assign discount factors, using procedures outlined in MacLean and Bolsinger (1974) and Hanson and others (2002). Only collected by certain FIA work units (SURVEY.RSCD = 26).

STND_COND_CD_PNWRS
Stand condition code, Pacific Northwest Research Station. A code that best describes the condition of the stand within forest condition classes. Stand condition is defined here as " the size, density, and species composition of a plant community following disturbance and at various time intervals after disturbance." Information on stand condition is used in describing wildlife habitat. Only collected by certain FIA work units (SURVEY.RSCD = 26).

Code Stand Condition Definition 0
Not applicable Condition class is juniper, chaparral, or curlleaf mountain mahogany forest type. 1 Grass-forb Shrubs <40 percent crown cover and <5 feet tall; plot may range from being largely devoid of vegetation to dominance by herbaceous species (grasses and forbs); tree regeneration generally <5 feet tall and 40 percent cover. 2 Shrub Shrubs 40 percent crown canopy or greater, of any height; trees <40 percent crown canopy and <1.0 inch DBH/DRC. When average stand diameter exceeds 1.0 inch DBH/DRC, plot is "open sapling" or "closed sapling." 3 Open sapling, poletimber Average stand diameter 1.0-8.9 inches DBH/DRC, and tree crown canopy poletimber <60 percent. 4 Closed sapling, pole, sawtimber Average stand diameter is 1.0-21.0 inches DBH/DRC and crown cover is 60 percent or greater. 5 Open sawtimber Average stand diameter is 9.0-21.0 inches DBH/DRC, and crown cover is <60 percent. 6 Large sawtimber Average stand diameter exceeds 21.0 inches DBH/DRC; crown cover may be <100 percent; decay and decadence required for old-growth characteristics is generally lacking, successional trees required by oldgrowth may be lacking, and dead and down material required by old-growth is lacking. 7 Old-growth Average stand diameter exceeds 21.0 inches DBH/DRC. Stands over 200 years old with at least two tree layers (overstory and understory), decay in living trees, snags, and down woody material. Some of the overstory layer may be composed of long-lived successional species (i.e., Douglas-fir, western redcedar).

STND_STRUC_CD_PNWRS
Stand structure code, Pacific Northwest Research Station. A code indicating the best overall structure of the stand. Only collected by certain FIA work units (SURVEY.RSCD = 26).

Code Stand Structure Definition 1
Even-aged singlestoried A single even canopy characterizes the stand. The greatest numbers of trees are in a height class represented by the average height of the stand; there are substantially fewer trees in height classes above and below this mean. The smaller trees are usually tall spindly members that have fallen behind their associates. The ages of trees usually do not differ by more than 20 years. 2 Even-aged twostoried Stands composed of two distinct canopy layers, such as, an overstory with an understory sapling layer possibly from seed tree and shelterwood operations. This may also be true in older plantations, where shade-tolerant trees may become established. Two relatively even canopy levels can be recognized in the stand. Understory or overtopped trees are common. Neither canopy level is necessarily continuous or closed, but both canopy levels tend to be uniformly distributed across the stand. The average age of each level differs significantly from the other. 3 Uneven-aged Theoretically, these stands contain trees of every age on a continuum from seedlings to mature canopy trees. In practice, uneven-aged stands are characterized by a broken or uneven canopy layer. Usually the largest number of trees is in the smaller diameter classes. As trees increase in diameter, their numbers diminish throughout the stand. Many times, instead of producing a negative exponential distribution of diminishing larger diameters, uneven-aged stands behave irregularly with waves of reproduction and mortality. Consider any stand with three or more structural layers as uneven-aged. Logging disturbances (examples are selection, diameter limit, and salvage cutting) will give a stand an unevenaged structure. 4 Mosaic At least two distinct size classes are represented and these are not uniformly distributed but are grouped in small repeating aggregations, or occur as stringers <120 feet wide, throughout the stand. Each size class aggregation is too small to be recognized and mapped as an individual stand. The aggregations may or may not be even-aged.

HARVEST_TYPE1_SRS
Harvest type code 1, Southern Research Station. This variable is populated when the corresponding variable TRTCD = 10. Only collected by certain FIA work units (SURVEY.RSCD = 33).

Code Description 11
Clearcut harvest -The removal of the majority of the merchantable trees in a stand; residual stand stocking is under 50 percent. 12 Partial harvest -Removal primarily consisting of highest quality trees. Residual consists of lower quality trees because of high grading or selection harvest. (i.e., Uneven aged, group selection, high grading, species selection) 13 Seed-tree/shelterwood harvest -Crop trees are harvested leaving seed source trees either in a shelterwood or seed tree. Also includes the final harvest of the seed trees. 14 Commercial thinning -The removal of trees (usually poletimber sized) from poletimber-sized stands leaving sufficient stocking of growing-stock trees to feature in future stand development. Also included are thinning in sawtimbersized stands where poletimber-sized (or log-sized) trees have been removed to improve quality of those trees featured in a final harvest. 15 Timber Stand Improvement (cut trees only) -The cleaning, release or other stand improvement involving non-commercial cutting applied to an immature stand that leaves sufficient stocking. 16 Salvage cutting -The harvesting of dead or damaged trees or of trees in danger of being killed by insects, disease, flooding, or other factors in order to save their economic value.

LAND_USE_SRS
Land use, Southern Research Station. A classification indicating the present land use of the condition. Collected on all condition records where SURVEY.RSCD = 33 and PLOT.DESIGNCD = 1, 230, 231, 232, or 233, and were processed in NIMS. It may not be populated for other SRS plot designs or for SRS data that have not been processed in NIMS. Only collected by certain FIA work units (SURVEY.RSCD = 33).

Code Description 01
Timber land (COND.SITECLCD = 1, 2, 3, 4, 5, or 6) 02 Other forest land (COND.SITECLCD = 7) 10 Agricultural land -Land managed for crops, pasture, or other agricultural use and is not better described by one of the following detailed codes. The area must be at least 1.0 acre in size and 120.0 feet wide. NOTE: Codes 14, 15 and 16 are collected only where PLOT.MANUAL ≥1. If PLOT.MANUAL <1, then codes 14 and 15 were coded 11. There was no single rule for coding maintained wildlife openings where PLOT.MANUAL <1, so code 16 may have been coded 10, 11 or 12. 11 Cropland 12 Pasture (improved through cultural practices) 13 Idle farmland 14 Orchard 15 Christmas tree plantation 16 Maintained wildlife openings 20 Rangeland -Land primarily composed of grasses, forbs, or shrubs. This includes lands vegetated naturally or artificially to provide a plant cover managed like native vegetation and does not meet the definition of pasture. The area must be at least 1.0 acre in size and 120.0 feet wide. 30 Developed -Land used primarily by humans for purposes other than forestry or agriculture and is not better described by one of the following detailed codes. NOTE: Code 30 is used to describe all developed land where PLOT.MANUAL <1. The following detailed codes only apply to PLOT.MANUAL ≥1. 31 Cultural: business, residential, and other places of intense human activity 32 Rights-of-way: improved roads, railway, power lines, maintained canal 33 Recreation: parks, skiing, golf courses 34 Mining 40 Other -Land parcels greater than 1.0 acre in size and greater than 120.0 feet wide that do not fall into one of the uses described above or below. 41 Marsh 42 Wetland 43 Beach 45 Nonforest-Chaparral 91 Census Water -Lakes, reservoirs, ponds, and similar bodies of water 4.5 acres in size and larger; and rivers, streams, canals, etc., 30 to 200 feet wide. 92 Noncensus water -Lakes, reservoirs, ponds, and similar bodies of water 1.0 acre to 4.5 acres in size. Rivers, streams, canals, etc., more than 200 feet wide. 99 Nonsampled -Condition not sampled (see COND.COND_NONSAMPLE_REASN_CD for exact reason).

OPERABILITY_SRS
Operability, Southern Research Station. The viability of operating logging equipment in the vicinity of the condition. The code represents the most limiting class code that occurs on each forest condition. Only collected by certain FIA work units (SURVEY.RSCD = 33).

Code Description
Seasonal access due to water conditions in wet weather. 2 Mixed wet and dry areas typical of multi-channeled streams punctuated with dry islands. 3 Broken terrain, cliffs, gullies, outcroppings, etc. that would severely limit equipment, access or use. 4 Year-round water problems (includes islands). 5 Slopes 20-40 percent. 6 Slope greater than 40 percent.

STAND_STRUCTURE_SRS
Stand structure, Southern Research Station. The description of the predominant canopy structure for the condition. Only the vertical position of the dominant and codominant trees in the stand are considered. Only collected by certain FIA work units (SURVEY.RSCD = 33).

Code Description 0
Non-stocked -The condition is less than 10 percent stocked. 1 Single-storied -Most of the dominant/codominant tree crowns form a single canopy (i.e., most of the trees are approximately the same height). 2 Two-storied -The dominant/codominant tree crowns form two distinct canopy layers or stories. 3 Multi-storied -More than two recognizable levels characterize the crown canopy. Dominant/codominant trees of many sizes (diameters and heights) for a multilevel canopy.

NF_COND_STATUS_CD
Nonforest condition status code. Intentionally left blank. Will be populated in version 5.0.

NF_COND_NONSAMPLE_REASN_CD
Nonforest condition nonsampled reason code. Intentionally left blank. Will be populated in version 5.0.

CANOPY_CVR_SAMPLE_METHOD_CD
Canopy cover sample method code. Intentionally left blank. Will be populated in version 5.0.

LIVE_CANOPY_CVR_PCT
Live canopy cover percent. Intentionally left blank. Will be populated in version 5.0.

LIVE_MISSING_CANOPY_CVR_PCT
Live plus missing canopy cover percent. Intentionally left blank. Will be populated in version 5.0.

NBR_LIVE_STEMS
Number of live stems. Intentionally left blank. Will be populated in version 5.0.

PREV_SBP_CN
Previous subplot sequence number. Foreign key linking the subplot record to the previous inventory's subplot record for this subplot. Only populated on annual remeasured plots.

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation.
The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system

POINT_NONSAMPLE_REASN_CD
Point nonsampled reason code. For entire subplots (or macroplots) that cannot be sampled, one of the following reasons is recorded.

Code Description 01
Outside U.S. boundary -Entire subplot (or macroplot) is outside of the U.S. border. 02 Denied access area -Access to the entire subplot (or macroplot) is denied by the legal owner, or by the owner of the only reasonable route to the subplot (or macroplot). 03 Hazardous situation -Entire subplot (or macroplot) cannot be accessed because of a hazard or danger, for example cliffs, quarries, strip mines, illegal substance plantations, high water, etc. 04 Time limitation -Entire subplot (or macroplot) cannot be sampled due to a time restriction. This code is reserved for areas with limited access, and in situations where it is imperative for the crew to leave before the plot can be completed (e.g., scheduled helicopter rendezvous). 05 Lost data -The plot data file was discovered to be corrupt after a panel was completed and submitted for processing. This code is assigned to entire plots or full subplots that could not be processed. 06 Lost plot -Entire plot cannot be found. Used for the four subplots that are required for this plot. 07 Wrong location -Previous plot can be found, but its placement is beyond the tolerance limits for plot location. Used for the four subplots that are required for this plot. 08 Skipped visit -Entire plot skipped. Used for plots that are not completed prior to the time a panel is finished and submitted for processing. Used for the four subplots that are required for this plot. This code is for office use only. 09 Dropped intensified plot -Intensified plot dropped due to a change in grid density. Used for the four subplots that are required for this plot. This code used only by units engaged in intensification. This code is for office use only. 10 Other -Entire subplot (or macroplot) not sampled due to a reason other than one of the specific reasons already listed. 11 Ocean -Subplot/macroplot falls in ocean water below mean high tide line.
12. MICRCOND Microplot center condition. Condition number for the condition at the center of the microplot.
13. SUBPCOND Subplot center condition. Condition number for the condition at the center of the subplot.
14. MACRCOND Macroplot center condition. Condition number for the condition at the center of the macroplot. Blank (null) if macroplot is not measured.
15. CONDLIST Subplot/macroplot condition list. (Core optional.) This is a listing of all condition classes located within the 24.0/58.9-foot radius around the subplot/macroplot center. A maximum of four conditions is permitted on any individual subplot/macroplot. For example: 2300 means these conditions (conditions 2 and 3) are on the subplot/macroplot.

SLOPE
Subplot slope. The angle of slope, in percent, of the subplot, determined by sighting along the average incline or decline of the subplot. If the slope changes gradually, an average slope is recorded. If the slope changes across the subplot but is predominantly of one direction, the predominant slope is recorded. Valid values are 0 through 155.
17. ASPECT Subplot aspect. The direction of slope, to the nearest degree, of the subplot, determined along the direction of slope. If the aspect changes gradually, an average aspect is recorded. If the aspect changes across the subplot but is predominantly of one direction, the predominant aspect is recorded. North is recorded as 360. When slope is <5 percent, there is no aspect and it is recorded as 000.
18. WATERDEP Snow/water depth. The approximate depth in feet of water or snow covering the subplot. Populated for all forested subplots using the National Field Guide protocols (PLOT.MANUAL ≥1.0) and populated by some FIA work units where PLOT.MANUAL <1.0.

P2A_GRM_FLG
Periodic to annual growth, removal, and mortality flag. A code indicating if this subplot is part of a periodic inventory (usually from a variable-radius plot design) that is only included for the purposes of computing growth, removals and/or mortality estimates. Tree data associated with this subplot does not contribute to current estimates of such attributes as volume, biomass or number of trees. The flag is set to Y for those subplots that are needed for estimation and otherwise is left blank (null). 20. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
26. CYCLE Inventory cycle number. A number assigned to a set of plots, measured over a particular period of time from which a State estimate using all possible plots is obtained. A cycle number >1 does not necessarily mean that information for previous cycles resides in the database. A cycle is relevant for periodic and annual inventories.
27. SUBCYCLE Inventory subcycle number. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process.

ROOT_DIS_SEV_CD_PNWRS
Root disease severity rating code, Pacific Northwest Research Station. The root disease severity rating that describes the degree of root disease present.

Code Description 0
No evidence of root disease visible within 50 feet of the 58.9 foot macroplot. 1 Root disease present within 50 feet of the macroplot, but no evidence of disease on the macroplot. 2 Minor evidence of root disease on the macroplot, such as suppressed tree killed by root disease, or a minor part of the overstory showing symptoms of infection. Little or no detectable reduction in canopy closure or volume. 3 Canopy reduction evident, up to 20 percent; usually as a result of death of 1 codominant tree on an otherwise fully stocked site. In absence of mortality, numerous trees showing symptoms of root disease infection. 4 Canopy reduction at least 20 percent; up to 30 percent as a result of root disease mortality. Snags and downed trees removed from canopy by disease as well as live trees with advance symptoms of disease contribute to impact. 5 Canopy reduction 30-50 percent as a result of root disease. At least half of the ground area of macroplot considered infested with evidence of root disease-killed trees. Macroplots representing mature stands with half of their volume in root disease-tolerant species usually do not go much above severity 5 because of the ameliorating effect of the disease-tolerant trees. 6 50-75 percent reduction in canopy with most of the ground area considered infested as evidenced by symptomatic trees. Much of the canopy variation in this category is generally a result of root disease-tolerant species occupying infested ground. 7 At least 75 percent canopy reduction. Macroplots that reach this severity level usually are occupied by only the most susceptible species. There are very few of the original overstory trees remaining although infested ground is often densely stocked with regeneration of susceptible species. 8 The entire macroplot falls within a definite root disease pocket with only one or very few susceptible overstory trees present. 9 The entire macroplot falls within a definite root disease pocket with no overstory trees of the susceptible species present. 3. INVYR Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation.
The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

MICRCOND_PROP
Microplot-condition proportion. Proportion of this microplot in this condition.

SUBPCOND_PROP
Subplot-condition proportion. Proportion of this subplot in this condition. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process.
Tree Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation.
The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system 11. CONDID Condition class number. Unique identifying number assigned to each condition on a plot. A condition is initially defined by condition class status. Differences in reserved status, owner group, forest type, stand-size class, regeneration status, and stand density further define condition for forest land.
Mapped nonforest conditions are also assigned numbers. At the time of the plot establishment, the condition class at plot center (the center of subplot 1) is usually designated as condition class 1. Other condition classes are assigned numbers sequentially at the time each condition class is delineated. On a plot, each sampled condition class must have a unique number that can change at remeasurement to reflect new conditions on the plot.
12. AZIMUTH Azimuth. The direction, to the nearest degree, from subplot center (microplot center for saplings) to the center of the base of the tree (geographic center for multi-stemmed woodland species). Due north is represented by 360 degrees. This attribute is populated for live and standing dead trees in a forest condition that were measured on any of the four subplots of the national plot design. It may be populated for other tree records.
13. DIST Horizontal distance. The horizontal distance in feet from subplot center (microplot center for saplings) to the center of the base of the tree (geographic center for multi-stemmed woodland species). This attribute is populated for live and standing dead trees in a forest condition that were measured on any of the four subplots of the national plot design. It may be populated for other tree records.
14. PREVCOND Previous condition number. Identifies the condition within the plot on which the tree occurred at the previous inventory.
15. STATUSCD Status code. A code indicating whether the sample tree is live, cut, or dead at the time of measurement. Includes dead and cut trees, which are required to estimate aboveground biomass and net annual volume for growth, mortality, and removals. This code is not used when querying data for change estimates. Note: New and replacement plots use only codes 1 and 2.
Code Description 0 No status -Tree is not presently in the sample (remeasurement plots only). Tree was incorrectly tallied at the previous inventory, currently not tallied due to definition or procedural change, or is not tallied due to natural causes. RECONCILECD = 5-9 required for remeasured annual inventory data but not for periodic inventory data. 1 Live tree 2 Dead tree 3 Removed -Cut and removed by direct human activity related to harvesting, silviculture or land clearing. This tree is assumed to be utilized. 23. TREECLCD Tree class code. A code indicating the general quality of the tree. In annual inventory, this is the tree class for both live and dead trees at the time of current measurement. In periodic inventory, for cut and dead trees, this is the tree class of the tree at the time it died or was cut. Therefore, cut and dead trees collected in periodic inventory can be coded as growing-stock.

SPCD
Code Description 2 Growing-stock -All live trees of commercial species that meet minimum merchantability standards. In general, these trees have at least one solid 8-foot section, are reasonably free of form defect on the merchantable bole, and at least 34 percent or more of the volume is merchantable. For the California, Oregon, and Washington inventories, a 26 percent or more merchantable volume standard is applied, rather than 34 percent or more. Excludes rough or rotten cull trees. 3 Rough cull -All live trees that do not now, or prospectively, have at least one solid 8-foot section, reasonably free of form defect on the merchantable bole, or have 67 percent or more of the merchantable volume cull; and more than half of this cull is due to sound dead wood cubic-foot loss or severe form defect volume loss. For the California, Oregon, and Washington inventories, 75 percent or more cull, rather than 67 percent or more cull, applies. This class also contains all trees of noncommercial species, or those species where SPGRPCD equals 23 (western woodland softwoods), 43 (eastern noncommercial hardwoods), or 48 (western woodland hardwoods). Refer to appendix F to find the species that have these SPGRPCD codes. For dead trees, this code indicates that the tree is salvable (sound). 4 Rotten cull -All live trees with 67 percent or more of the merchantable volume cull, and more than half of this cull is due to rotten or missing cubic-foot volume loss. California, Oregon, and Washington inventories use a 75 percent cutoff. For dead trees, this code indicates that the tree is nonsalvable (not sound).

CR
Compacted crown ratio. The percent of the tree bole supporting live, healthy foliage (the crown is ocularly compacted to fill in gaps) when compared to actual length (ACTUALHT). When PLOT.MANUAL <1.0 the variable may have been a code, which was converted to the midpoint of the ranges represented by the codes, and is stored as a percentage.
25. CCLCD Crown class code. A code indicating the amount of sunlight received and the crown position within the canopy.
Code Description 1 Open grown -Trees with crowns that have received full light from above and from all sides throughout all or most of their life, particularly during early development. 2 Dominant -Trees with crowns extending above the general level of the canopy and receiving full light from above and partly from the sides; larger than the average trees in the stand, and with crowns well developed, but possibly somewhat crowded on the sides. 3 Codominant -Trees with crowns forming part of the general level of the crown cover and receiving full light from above, but comparatively little from the side. Usually with medium crowns more or less crowded on the sides. 4 Intermediate -Trees shorter than those in the preceding two classes, with crowns either below or extending into the canopy formed by the dominant and codominant trees, receiving little direct light from above, and none from the sides; usually with small crowns very crowded on the sides. 5 Overtopped -Trees with crowns entirely below the general canopy level and receiving no direct light either from above or the sides.
26. TREEGRCD Tree grade code. A code indicating the quality of sawtimber-sized trees. This attribute is populated for live, growing-stock, sawtimber size trees on subplots 1-4 on national manual plots that are in a forest condition class. This attribute may be populated for other tree records that do not meet the above criteria. For example, it may be populated with the previous tree grade on dead and cut trees. Standards for tree grading are specific to species and differ slightly by research station. Only collected by certain FIA work units (SURVEY.RSCD = 23, 24, or 33). Tree grade codes range from 1 to 5.
27. AGENTCD Cause of death (agent) code. (Core: all remeasured plots when the tree was alive at the previous visit and at revisit is dead or removed OR the tree is standing dead in the current inventory and the tree is ingrowth, through growth, or a missed live tree; Core optional: all initial plot visits when tree qualifies as a mortality tree.) When PLOT.MANUAL ≥1.0, this variable was collected on only dead and cut trees. When PLOT.MANUAL <1.0, this variable was collected on all trees (live, dead, and cut). Cause of damage was recorded for live trees if the presence of damage or pathogen activity was serious enough to reduce the quality or vigor of the tree. When a tree was damaged by more than one agent, the most severe damage was coded. When no damage was observed on a live tree, 00 was recorded. Damage recorded for dead trees was the cause of death. When the cause of death could not be determined for a tree, 99 was recorded. Each FIA program records specific codes that may differ from one State to the next. These codes fall within the ranges listed below. For the specific codes used in a particular State, contact the FIA work unit responsible for that State (table 6). 28. CULL Rotten and missing cull. The percent of the cubic-foot volume in a live or dead tally tree that is rotten or missing. This is a calculated value that includes field-recorded cull (CULL_FLD) and any additional cull due to broken top.

DAMLOC1
Damage location 1. (Core where PLOT.MANUAL = 1.0 through 1.6; Core optional beginning with PLOT.MANUAL = 1.7.) A code indicating where damage (meeting or exceeding a severity threshold, as defined in the field guide) is present on the tree.

Code Description 0
No damage 1 Roots (exposed) and stump (up to 12 inches from ground level) 2 Roots, stump, and lower bole 3 Lower bole (lower half of bole between stump and base of live crown) 4 Lower and upper bole 5 Upper bole (upper half of bole between stump and base of live crown) 6 Crownstem (main stem within the live crown) 7 Branches (>1 inch diameter at junction with main stem and within the live crown) 8 Buds ), VOLCFNET is the net volume of wood and bark from the DRC measurement point(s) to a 1½ -inch top diameter; includes branches that are at least 1½ inches in diameter along the length of the branch. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for trees with DIA <5.0 inches. All trees measured after 1998 with DIA ≥5.0 inches (including dead and cut trees) will have entries in this field. Does not include rotten, missing, and form cull (volume loss due to rotten, missing, and form cull defect has been deducted).

VOLCFGRS
Gross cubic-foot volume. For timber species (trees where the diameter is measured at breast height [DBH]), this is the total volume of wood in the central stem of sample trees ≥5.0 inches in diameter, from a 1-foot stump to a minimum 4-inch top diameter, or to where the central stem breaks into limbs all of which are <4.0 inches in diameter. For woodland species (trees where the diameter is measured at root collar [DRC]), VOLCFGRS is the total volume of wood and bark from the DRC measurement point(s) to a 1½ -inch top diameter; includes branches that are at least 1½ inches in diameter along the length of the branch. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for trees with DIA <5.0 inches. All trees measured after 1998 with DIA ≥5.0 inches (including dead and cut trees) have entries in this field. Includes rotten, missing and form cull (volume loss due to rotten, missing, and form cull defect has not been deducted).

VOLCSNET
Net cubic-foot volume in the sawlog portion. The net volume of wood in the central stem of a timber species tree of sawtimber size (9.0 inches DIA minimum for softwoods, 11.0 inches DIA minimum for hardwoods), from a 1-foot stump to a minimum top diameter, (7.0 inches for softwoods, 9.0 inches for hardwoods) or to where the central stem breaks into limbs, all of which are less than the minimum top diameter. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for softwood trees with DIA <9.0 inches (11.0 inches for hardwoods). All larger trees have entries in this field if they are growingstock trees (TREECLCD = 2 and STATUSCD = 1). All rough and rotten trees (TREECLCD = 3 or 4) and dead and cut trees (STATUSCD = 2 or 3) are blank (null) in this field.

VOLCSGRS
Gross cubic-foot volume in the sawlog portion. This is the total volume of wood in the central stem of a timber species tree of sawtimber size (9.0 inches DIA minimum for softwoods, 11.0 inches DIA minimum for hardwoods), from a 1-foot stump to a minimum top diameter (7.0 inches for softwoods, 9.0 inches for hardwoods), or to where the central stem breaks into limbs, all of which are less than the minimum top diameter. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for softwood trees with DIA <9.0 inches (11.0 inches for hardwoods). All larger trees have entries in this field if they are growing-stock trees (TREECLCD = 2 and STATUSCD = 1). All rough and rotten trees (TREECLCD = 3 or 4) and dead and cut trees (STATUSCD = 2 or 3) are blank (null) in this field.

VOLBFNET
Net board-foot volume in the sawlog portion. This is the net volume (International ¼-inch rule) of wood in the central stem of a timber species tree of sawtimber size (9.0 inches DIA minimum for softwoods, 11.0 inches DIA minimum for hardwoods), from a 1-foot stump to a minimum top diameter (7.0 inches for softwoods, 9.0 inches for hardwoods), or to where the central stem breaks into limbs all of which are less than the minimum top diameter. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per unit area information. This attribute is blank (null) for softwood trees with DIA <9.0 inches (11.0 inches for hardwoods). All larger trees should have entries in this field if they are growing-stock trees (TREECLCD = 2 and STATUSCD = 1). All rough and rotten trees (TREECLCD = 3 or 4) and dead and cut trees (STATUSCD = 2 or 3) are blank (null) in this field.

VOLBFGRS
Gross board-foot volume in the sawlog portion. This is the total volume (International ¼-inch rule) of wood in the central stem of a timber species tree of sawtimber size (9.0 inches DIA minimum for softwoods, 11.0 inches DIA minimum for hardwoods), from a 1-foot stump to a minimum top diameter (7.0 inches for softwoods, 9.0 inches for hardwoods), or to where the central stem breaks into limbs all of which are less than the minimum top DIA. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per unit area information. This attribute is blank (null) for softwood trees with DIA <9.0 inches (11.0 inches for hardwoods). All larger trees should have entries in this field if they are growing-stock trees (TREECLCD = 2 and STATUSCD = 1). All rough and rotten trees (TREECLCD = 3 or 4) and dead and cut trees (STATUSCD = 2 or 3) are blank (null) in this field.
44. VOLCFSND Sound cubic-foot volume. For timber species (trees where the diameter is measured at breast height [DBH]), the volume of sound wood in the central stem of a sample tree ≥5.0 inches in diameter from a 1-foot stump to a minimum 4-inch top diameter or to where the central stem breaks into limbs all of which are <4.0 inches in diameter. For woodland species (trees where the diameter is measured at root collar [DRC]), VOLCFSND is the net volume of wood and bark from the DRC measurement point(s) to a minimum 1½ -inch top diameter; includes branches that are at least 1½ inches in diameter along the length of the branch. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for trees with DIA <5.0 inches. All trees with DIA ≥5.0 inches (including dead trees) have entries in this field. Does not include rotten and missing cull (volume loss due to rotten and missing cull defect has been deducted).
45. GROWCFGS Net annual merchantable cubic-foot growth of a growing-stock tree on timberland. This is the net change in cubic-foot volume per year of this tree (for remeasured plots, (V 2 -V 1 )/(t 2 -t 1 ); where 1 and 2 denote the past and current measurement, respectively, V is volume, and t indicates year of measurement). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ.
46. GROWBFSL Net annual merchantable board-foot growth of a sawtimber size tree on timberland. This is the net change in board-foot (International ¼-inch rule) volume per year of this tree (for remeasured plots (V 2 -V 1 )/(t 2 -t 1 )). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ.
47. GROWCFAL Net annual sound cubic-foot growth of a live tree on timberland. The net change in cubic-foot volume per year of this tree (for remeasured plots (V 2 -V 1 )/(t 2 -t 1 )). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ. GROWCFAL differs from GROWCFGS by including all trees, regardless of tree class.
48. MORTCFGS Cubic-foot volume of a growing-stock tree on timberland for mortality purposes. Represents the cubic-foot volume of a growing-stock tree at time of death. To obtain estimates of annual per acre mortality, multiply by TPAMORT_UNADJ.
49. MORTBFSL Board-foot volume of a sawtimber size tree on timberland for mortality purposes. Represents the board-foot (International ¼-inch rule) volume of a sawtimber tree at time of mortality. To obtain estimates of annual per acre mortality, multiply by TPAMORT_UNADJ.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
87. MORTCD Mortality code. (Core optional.) Used for a tree that was alive within past 5 years, but has died. Through growth -new tally tree 5 inches DBH/DRC and larger, within the microplot, which was not missed at the previous inventory. 3 Missed live -a live tree missed at previous inventory and that is live, dead, or removed now. 4 Missed dead -a dead tree missed at previous inventory and that is dead or removed now. 5 Shrank -live tree that shrunk below threshold diameter on microplot/subplot/macroplot plot. 6 Missing (moved) -tree was correctly tallied in previous inventory, but has now moved beyond the radius of the plot due to natural causes (i.e., small earth movement, hurricane). Tree must be either live before and still alive now or dead before and dead now. If tree was live before and now dead, this is a mortality tree and should have STATUSCD = 2 (not 0). 7 Cruiser error -erroneously tallied at previous inventory 8 Procedural change -tree was tallied at the previous inventory, but is no longer tallied due to a definition or procedural change. 9 Tree was sampled before, but now the area where the tree was located is nonsampled. All trees on the nonsampled area have RECONCILECD = 9.
93. PREVDIA Previous diameter. The previous diameter (in inches) of the sample tree at the point of diameter measurement. Populated for remeasured trees.
94. FGROWCFGS Net annual merchantable cubic-foot growth of a growing-stock tree on forest land. This is the net change in cubic-foot volume per year of this tree (for remeasured plots, (V 2 -V 1 )/(t 2 -t 1 ); where 1 and 2 denote the past and current measurement, respectively, V is volume, t indicates date of measurement, and t 2 -t 1 = PLOT.REMPER). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ.
95. FGROWBFSL Net annual merchantable board-foot growth of a sawtimber tree on forest land. This is the net change in board-foot (International ¼ -inch rule) volume per year of this tree (for remeasured plots (V 2 -V 1 )/(t 2 -t 1 )). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ.
96. FGROWCFAL Net annual sound cubic-foot growth of a live tree on forest land. The net change in cubic-foot volume per year of this tree (for remeasured plots (V 2 -V 1 )/(t 2 -t 1 )). Because this value is net growth, it may be a negative number. Negative growth values are usually due to mortality (V 2 = 0) but can also occur on live trees that have a net loss in volume because of damage, rot, broken top, or other causes. To expand to a per acre value, multiply by TPAGROW_UNADJ. FGROWCFAL differs from FGROWCFGS by including all trees, regardless of tree class.
97. FMORTCFGS Cubic-foot volume of a growing-stock tree for mortality purposes on forest land. Represents the cubic-foot volume of a growing-stock tree at time of mortality. To obtain estimates of annual per acre mortality, multiply by TPAMORT_UNADJ.
98. FMORTBFSL Board-foot volume of a sawtimber tree for mortality purposes on forest land. Represents the board-foot (International ¼-rule) volume of a sawtimber tree at time of mortality. To obtain estimates of annual per acre mortality, multiply by TPAMORT_UNADJ.
99. FMORTCFAL Sound cubic-foot volume of a tree for mortality purposes on forest land. Represents the cubic-foot volume of the tree at time of mortality. To obtain estimates of annual per acre mortality, multiply by TPAMORT_UNADJ. FMORTCFAL differs from FMORTCFGS by including all trees, regardless of tree class.
100. FREMVCFGS Cubic-foot volume of a growing-stock tree for removal purposes on forest land. Represents the cubic-foot volume of the tree at time of removal. To obtain estimates of annual per acre removals, multiply by TPAREMV_UNADJ.
101. FREMVBFSL Board-foot volume of a sawtimber size tree for removal purposes on forest land. Represents the board-foot (International ¼-rule) volume of the tree at time of removal. To obtain estimates of annual per acre removals, multiply by TPAREMV_UNADJ.
102. FREMVCFAL Sound cubic-foot volume of the tree for removal purposes on forest land. Represents the cubic-foot volume of the tree at time of removal. To obtain estimates of annual per acre removals, multiply by TPAREMV_UNADJ. FREMVCFAL differs from FREMVCFGS by including all trees, regardless of tree class.

P2A_GRM_FLG
Periodic to annual growth, removal, and mortality flag. A code indicating if this tree is part of a periodic inventory (usually from a variable-radius plot design) that is only included for the purposes of computing growth, removals and/or mortality estimates. This tree does not contribute to current estimates of such attributes as volume, biomass or number of trees. The flag is set to Y for those trees that are needed for estimation and otherwise is left blank (null).

TREECLCD_NERS
Tree class code, Northeastern Research Station. In annual inventory, this code represents a classification of the overall quality of a tree that is 5.0 inches DBH and larger. It classifies the quality of a sawtimber tree based on the present condition, or it classifies the quality of a poletimber tree as a prospective determination (i.e., a forecast of potential quality when and if the tree becomes sawtimber size). For more detailed description, see the regional field guide. Only collected by certain FIA work units (SURVEY.RSCD = 24).

Code Description 1
Preferred -Live tree that would be favored in cultural operations. Mature tree, that is older than the rest of the stand; has less than 20 percent total board foot cull; is expected to live for 5 more years: and is a low risk tree. In general, the tree has the following qualifications: • must be free from "general" damage (i.e., damages that would now or prospectively cause a reduction of tree class, significantly deter growth, or prevent it from producing marketable products in the next 5 years). • should have no more than 10 percent board-foot cull due to form defect.
• should have good vigor, usually indicated by a crown ratio of 30 percent or more and dominant or co-dominant. • usually has a grade 1 butt log. 2 Acceptable -This class includes: • live sawtimber tree that does not qualify as a preferred tree but is not a cull tree (see Rough and Rotten Cull). • live poletimber tree that prospectively will not qualify as a preferred tree, but is not now or prospectively a cull tree (see Rough and Rotten Cull). 3 Rough Cull -This class includes: • live sawtimber tree that currently has 67 percent or more predominantly sound board-foot cull; or does not contain one merchantable 12-foot sawlog or two non-contiguous merchantable 8-foot sawlogs. • live poletimber tree that currently has 67 percent or more predominantly sound cubic-foot cull; or prospectively will have 67 percent or more predominantly sound board-foot cull; or will not contain one merchantable 12-foot sawlog or two noncontiguous merchantable 8-foot sawlogs. 4 Rotten Cull -This class includes: • live sawtimber tree that currently has 67 percent or more predominantly unsound board-foot cull. • live poletimber tree that currently has 67 percent or more predominantly unsound cubic-foot cull; or prospectively will have 67 percent or more predominantly unsound board-foot cull. 5 Dead -Tree that has recently died (within the last several years); but still retains many branches (including some small branches and possibly some fine twigs); and has bark that is generally tight and hard to remove from the tree. 6 Snag -Dead tree, or what remains of a dead tree, that is at least 4.5 feet tall and is missing most of its bark. This category includes a tree covered with bark that is very loose. This bark can usually be removed, often times in big strips, with very little effort. A snag is not a recently dead tree. Most often, it has been dead for several years -sometimes, for more than a decade.

TREECLCD_SRS
Tree class code, Southern Research Station. A code indicating the general quality of the tree. Prior to the merger of the Southern and Southeastern Research Stations (INVYR ≤1997), growing-stock (code 2) was only assigned to species that were considered to have commercial value. Since the merger (INVYR >1997), code 2 has been applied to all tree species meeting the growing-stock form, grade, size and soundness requirements, regardless of commercial value. Only collected by certain FIA work units (SURVEY.RSCD = 33).
Code Description 2 Growing-stock -All trees that have at least one 12-foot log or two 8-foot logs that meet grade and size requirements and at least ⅓ of the total board foot volume is merchantable. Poletimber-sized trees are evaluated based on their potential. 3 Rough cull -Trees that do not contain at least one 12-foot log or two 8-foot logs, or more than ⅓ of the total board foot volume is not merchantable, primarily due to roughness or poor form. 4 Rotten cull: Trees that do not contain at least one 12-foot log or two 8-foot logs, or more than ⅓ of the total board foot volume is not merchantable, primarily due to rotten, unsound wood.

TREECLCD_NCRS
Tree class code, North Central Research Station. In annual inventory, a code indicating tree suitability for timber products, or the extent of decay in the butt section of down-dead trees. It is recorded on live standing, standingdead, and down dead trees that are 1.0 inches DBH and larger. Tree class is basically a check for the straightness and soundness of the sawlog portion on a sawtimber tree or the potential sawlog portion on a poletimber tree or sapling. "Sawlog portion" is defined as the length between the 1-foot stump and the 9.0-inch top diameter of outside bark, DOB, for hardwoods, or the 7.0-inch top DOB for softwoods. For more detailed description, see the regional field guide http://www.nrs.fs.fed.us/fia/data-collection/. Only collected by certain FIA work units (SURVEY.RSCD = 23).

Code Description 20
Growing-stock -Any live tree of commercial species that is saw-timber size and has at least one merchantable 12-foot sawlog or two merchantable 8-foot sawlogs meeting minimum log-grade requirements. At least onethird of the gross board-foot volume of the sawlog portion must be merchantable material. A merchantable sawlog must be at least 50 percent sound at any point. Any pole timber size tree that has the potential to meet the above specifications. 30 Rough Cull, Salvable, and Salvable-down -Includes any tree of noncommercial species, or any tree that is saw-timber size and has no merchantable sawlog. Over one-half of the volume in the sawlog portion does not meet minimum log-grade specifications due to roughness, excessive sweep or crook, splits, cracks, limbs, or forks. Rough cull polesize trees do not have the potential to meet the specifications for growingstock because of forks, limb stoppers, or excessive sweep or crook. A down-dead tree ≥5.0-inch DBH that meets these standards is given a tree/decay code of 30. 31 Short-log Cull -Any live saw-timber-size tree of commercial species that has at least one 8-foot sawlog, but less than a 12-foot sawlog, meeting minimum log-grade specifications. Any live saw-timber-size tree of commercial species that has less than one-third of the volume of the sawlog portion in merchantable logs, but has at least one 8-foot or longer sawlog meeting minimum log-grade specifications. A short sawlog must be 50 percent sound at any point. Pole-size trees never receive a tree class code 31. 40 Rotten Cull -Any live tree of commercial species that is saw-timber size and has no merchantable sawlog. Over one-half of the volume in the sawlog portion does not meet minimum log-grade specifications primarily because of rot, missing sections, or deadwood. Classify any pole-size tree that does not have the potential to meet the specifications for growingstock because of rot as rotten cull. Assume that all live trees will eventually attain sawlog size at DBH. Predicted death, tree vigor, and plot site index are not considered in determining tree class. A standing-dead tree without an 8-foot or longer section that is at least 50 percent sound has a tree class of 40. On remeasurement of a sapling, if it has died and is still standing it is given a tree class of 40.

TREECLCD_RMRS
Tree class code, Rocky Mountain Research Station. A code indicating the general quality of the tree. Only collected by certain FIA work units (SURVEY.RSCD = 22).

Code Description 1
Sound-live timber species -All live timber trees (species with diameter measured at breast height) that meet minimum merchantability standards. In general, these trees have at least one solid 8-foot section, are reasonably free of form defect on the merchantable bole, and at least 34 percent or more of the volume is merchantable. Excludes rough or rotten cull timber trees. 2 All live woodland species -All live woodland trees (species with diameter measured at root collar). All trees assigned to species groups 23 and 48 belong in this category (see appendix G).

Code Description 3
Rough-live timber species -All live trees that do not now, or prospectively, have at least one solid 8-foot section, reasonably free of form defect on the merchantable bole, or have 67 percent or more of the merchantable volume cull; and more than half of this cull is due to sound dead wood cubic-foot loss or severe form defect volume loss. 4 Rotten-live timber species -All live trees with 67 percent or more of the merchantable volume cull, and more than half of this cull is due to rotten or missing cubic-foot volume loss. 5 Hard (salvable) dead -dead trees that have less than 67 percent of the volume cull due to rotten or missing cubic-foot volume loss. 6 Soft (nonsalvable) dead -dead trees that have 67 percent or more of the volume cull due to rotten or missing cubic-foot volume loss.

STANDING_DEAD_CD
Standing dead code. A code indicating if a tree qualifies as standing dead. To qualify as a standing dead tally tree, the dead tree must be at least 5.0 inches in diameter, have a bole that has an unbroken actual length of at least 4.5 feet, and lean less than 45 degrees from vertical as measured from the base of the tree to 4.5 feet. Populated where PLOT.MANUAL ≥2.0; may be populated using information collected on dead trees in earlier inventories for dead trees.
For western woodland species with multiple stems, a tree is considered down if more than ⅔ of the volume is no longer attached or upright; cut and removed volume is not considered. For western woodland species with single stems to qualify as a standing dead tally tree, dead trees must be at least 5.0 inches in diameter, be at least 1.0 foot in unbroken ACTUAL LENGTH, and lean less than 45 degrees from vertical. 111. TPA_UNADJ Trees per acre unadjusted. The number of trees per acre that the sample tree theoretically represents based on the sample design. For fixed radius plots taken with the mapped plot design (PLOT.DESIGNCD = 1), TPA_UNADJ is set to a constant derived from the plot size and equals 6.018046 for trees sampled on subplots, 74.965282 for trees sampled on microplots, and 0.999188 for trees sampled on macroplots. Variable radius plots were often used in earlier inventories, so the value in TPA_UNADJ decreases as the tree diameter increases. Based on the procedures described in Bechtold and Patterson (2005), this attribute can be adjusted using factors stored on the POP_STRATUM table to derive population estimates. Examples of estimating population totals are shown in chapter 4.

TPAMORT_UNADJ
Mortality trees per acre unadjusted. The number of mortality trees per acre per year that the sample tree theoretically represents based on the sample design. For fixed radius plots taken with the mapped plot design (PLOT.DESIGNCD =1), TPAMORT_UNADJ is set to a constant derived from the plot size divided by PLOT.REMPER. Variable radius plots were often used in earlier inventories, so the value in TPAMORT_UNADJ decreases as the tree diameter increases. This attribute will be blank (null) if the tree does not contribute to mortality estimates. Based on the procedures described in Bechtold and Patterson (2005), this attribute can be adjusted using factors stored on the POP_STRATUM table to derive population estimates. Examples of estimating population totals are shown in chapter 4.

TPAREMV_UNADJ
Removal trees per acre unadjusted. The number of removal trees per acre per year that the sample tree theoretically represents based on the sample design. For fixed radius plots taken with the mapped plot design (PLOT.DESIGNCD =1), TPAREMV_UNADJ is set to a constant derived from the plot size divided by PLOT.REMPER. Variable radius plots were often used in earlier inventories, so the value in TPAREMV_UNADJ decreases as the tree diameter increases. This attribute will be blank (null) if the tree does not contribute to removals estimates. Based on the procedures described in Bechtold and Patterson (2005), this attribute can be adjusted using factors stored on the POP_STRATUM table to derive population estimates. Examples of estimating population totals are shown in chapter 4.

TPAGROW_UNADJ
Growth trees per acre unadjusted. The number of growth trees per acre that the sample tree theoretically represents based on the sample design. For fixed radius plots taken with the mapped plot design (PLOT.DESIGNCD = 1), TPAGROW_UNADJ is set to a constant derived from the plot size. Variable radius plots were often used in earlier inventories, so the value in TPAGROW_UNADJ decreases as the tree diameter increases. This attribute will be blank (null) if the tree does not contribute to growth estimates. Based on the procedures described in Bechtold and Patterson (2005), this attribute can be adjusted using factors stored on the POP_STRATUM

DRYBIO_SAPLING
Dry biomass of saplings. The oven-dry biomass (pounds) of the aboveground portion, excluding foliage, of live trees with a diameter from 1 to 4.9 inches. Calculated for timber species only. The biomass of saplings is based on biomass computed from Jenkins and others (2003), using the observed diameter and an adjustment factor. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Appendix J contains equations used to estimate biomass components in the FIADB.

DRYBIO_WDLD_SPP
Dry biomass of woodland tree species. The oven-dry biomass (pounds) of the aboveground portion of a live or dead tree, excluding foliage, the tree tip (top of the tree above 1½ inches in diameter), and a portion of the stump from ground to diameter at root collar (DRC). Calculated for woodland species (trees where diameter is measured at DRC) with a diameter ≥1 inch. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. This attribute is blank (null) for woodland species with DIA <1.0 inch and for all timber species. Appendix J contains equations used to estimate biomass components in the FIADB.
120. DRYBIO_BG Dry biomass of the roots. The oven-dry biomass (pounds) of the belowground portion of a tree, includes coarse roots with a root diameter ≥0.1 inch. This is a modeled estimate, calculated on live trees with a diameter of ≥1 inch and dead trees with a diameter of ≥5 inches, for both timber and woodland. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Appendix J contains equations used to estimate biomass components in the FIADB.
121. CARBON_AG Carbon in the aboveground portion of the tree. The carbon (pounds) in the aboveground portion, excluding foliage, of live trees with a diameter ≥1 inch, and dead trees with a diameter ≥5 inches. Calculated for both timber and woodland species. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Carbon is assumed to be onehalf the value of biomass and is derived by summing the aboveground biomass estimates and multiplying by 0.5 as follows: CARBON_AG = 0.5 * (DRYBIO_BOLE + DRYBIO_STUMP + DRYBIO_TOP + DRYBIO_SAPLING + DRYBIO_WDLD_SPP) 122. CARBON_BG Carbon in the belowground portion of the tree. The carbon (pounds) of coarse roots >0.1 inch in root diameter. Calculated for live trees with a diameter ≥1 inch, and dead trees with a diameter ≥5 inches, for both timber and woodland species. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Carbon is assumed to be onehalf the value of belowground biomass as follows: Seedling data collection overview -When PLOT.MANUAL <2.0, the national core procedure was to record the actual seedling count up to six seedlings and then record 6+ if at least six seedlings were present. However, the following regions collected the actual seedling count when PLOT.MANUAL <2.0: Rocky Mountain Research Station (RMRS) and North Central Research Station (NCRS). If PLOT.MANUAL <2.0 and TREECOUNT is blank (null), then a value of 6 in TREECOUNT_CALC represents 6 or more seedlings. In the past, seedlings were often tallied in FIA inventories only to the extent necessary to determine if some minimum number were present, which means that seedlings were often under-reported. Note: The SEEDLING record may not exist for some periodic inventories.
1. CN Sequence number. A unique index used to easily identify a seedling.
2. PLT_CN Plot sequence number. Foreign key linking the seedling record to the plot record.

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed 9. CONDID Condition class number. Unique identifying number assigned to each condition on a plot. A condition is initially defined by condition class status. Differences in reserved status, owner group, forest type, stand-size class, regeneration status, and stand density further define condition for forest land. Mapped nonforest conditions are also assigned numbers. At the time of the plot establishment, the condition class at plot center (the center of subplot 1) is usually designated as condition class 1. Other condition classes are assigned numbers sequentially at the time each condition class is delineated. On a plot, each sampled condition class must have a unique number that can change at remeasurement to reflect new conditions on the plot.
10. SPCD Species code. An FIA species code. Refer to appendix F for codes.
11. SPGRPCD Species group code. A code assigned to each tree species in order to group them for reporting purposes on presentation tables. Codes and their associated names (see REF_SPECIES_GROUP.NAME) are shown in appendix G. Individual tree species and corresponding species group codes are shown in appendix F.

STOCKING
Tree stocking. The stocking value assigned to each count of seedlings, by species. Stocking is a relative term used to describe (in percent) the adequacy of a given stand density in meeting a specific management objective. Species or forest type stocking functions were used to assess the stocking contribution of seedling records. These functions, which were developed using stocking guides, relate the area occupied by an individual tree to the area occupied by a tree of the same size growing in a fully stocked stand of like trees. The stocking of seedling count records is used in the calculation of COND.GSSTKCD and COND.ALSTKCD on the condition record.
13. TREECOUNT Tree count (for seedlings). Indicates the number of seedlings (DIA <1.0 inch) present on the microplot. Conifer seedlings are at least 6 inches tall and hardwood seedlings are at least 12 inches tall. When PLOT.MANUAL <2.0, the national core procedure was to record the actual seedling count up to six seedlings and then record 6+ if at least six seedlings were present. However, the following regions collected the actual seedling count when PLOT.MANUAL <2.0: Rocky Mountain Research Station (RMRS) and North Central Research Station (NCRS). If PLOT.MANUAL <2.0 and TREECOUNT is blank (null), then a value of 6 in TREECOUNT_CALC represents 6 or more seedlings.
14. TOTAGE Total age. The seedling's total age. Total age is collected for a subset of seedling count records, using one representative seedling for the species. The age is obtained by counting the terminal bud scars or the whorls of branches and may be used in the stand age calculation.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

TREECOUNT_CALC
Tree count used in calculations. This attribute is set either to COUNTCD, which was dropped in FIADB version 2.1, or TREECOUNT. When PLOT.MANUAL <2.0, the national core procedure was to record the actual seedling count up to six seedlings and then record 6+ if at least six seedlings were present. However, the following regions collected the actual seedling count when PLOT.MANUAL <2.0: Rocky Mountain Research Station (RMRS) and North Central Research Station (NCRS). If PLOT.MANUAL <2.0 and TREECOUNT is blank (null), then a value of 6 in TREECOUNT_CALC represents 6 or more seedlings.
22. TPA_UNADJ Trees per acre unadjusted. The number of seedlings per acre that the seedling count theoretically represents based on the sample design. For fixed radius plots taken with the mapped plot design (PLOT.DESIGNCD =1), TPA_UNADJ equals 74.965282 times the number of seedlings counted. For plots taken with other sample designs, this attribute may be blank (null). Based on the procedures described in Bechtold and Patterson (2005), this attribute can be adjusted using factors stored on the POP_STRATUM 24. SUBCYCLE Inventory subcycle number. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process.

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system 15. SPGRPCD Species group code. A code assigned to each tree species in order to group them for reporting purposes on presentation tables. Codes and their associated names (see REF_SPECIES_GROUP.NAME) are shown in appendix G. Individual tree species and corresponding species group codes are shown in appendix F.

SITREE
Site index for the tree. Site index is calculated for dominant and co-dominant trees using one of several methods (see METHOD). It is expressed as height in feet that the tree is expected to attain at a base-or reference age (see SIBASE). Most commonly, site index is calculated using a family of curves that show site index as a function of total length and either breast-height age or total age. The height-intercept (or growth-intercept) method is commonly used for young trees or species that produce conspicuous annual branch whorls; using this method, site index is calculated with the height growth attained for a short period (usually 3 to 5 years) after the tree has reached breast height. Neither age nor total length determination are necessary when using the height-intercept method, so one or more of those variables may be null for a site tree on which the height-intercept method was used.
17. SIBASE Site index base age. The base age (sometimes called reference age), in years, of the site index curves used to derive site index. Base age is specific to a given family of site index curves, and is usually set close to the common rotation age or the age of culmination of mean annual increment for a species.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CYCLE
Inventory cycle number. A number assigned to a set of plots, measured over a particular period of time from which a State estimate using all possible plots is obtained. A cycle number >1 does not necessarily mean that information for previous cycles resides in the database. A cycle is relevant for periodic and annual inventories.
32. SUBCYCLE Inventory subcycle number. For an annual inventory that takes n years to measure all plots, subcycle shows in which of the n years of the cycle the data were measured. Subcycle is 0 for a periodic inventory. Subcycle 99 may be used for plots that are not included in the estimation process. Boundary

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (SURVEY.RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005.
INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system New boundary, or boundary data have been changed to reflect an actual on-theground physical change resulting in a difference from the boundaries recorded. 2 Boundary has been changed to correct an error from a previous crew. 3 Boundary has been changed to reflect a change in variable definition.
11. CONTRAST Contrasting condition. The condition class number of the condition class that contrasts with the condition class located at the subplot center (for boundaries on the subplot or macroplot) or at the microplot center (for boundaries on the microplot), e.g., the condition class present on the other side of the boundary.
12. AZMLEFT Left azimuth. The azimuth, to the nearest degree, from the subplot, microplot, or macroplot plot center to the farthest left point (facing the contrasting condition class) where the boundary intersects the subplot, microplot, or macroplot plot circumference.
13. AZMCORN Corner azimuth. The azimuth, to the nearest degree, from the subplot, microplot, or macroplot plot center to a corner or curve in a boundary. If a boundary is best described by a straight line between the two circumference points, then 000 is recorded for AZMCORN.
14. DISTCORN Corner distance. The horizontal distance, to the nearest 1 foot, from the subplot, microplot, or macroplot plot center to the boundary corner point.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. This table contains information about the mix of current and previous conditions that occupy the same area on the subplot. Figure 5 provides an illustration of how the information in this table is derived using data from two points in time that is stored in the BOUNDARY and COND tables.

SUBPTYP_PROP_CHNG
Subplot type proportion change. The unadjusted proportion of the subplot that is in the same geographic area condition for both the previous and current inventory. The sum of all subplot type change proportions for an individual plot equals 4 for each plot type (microplot, subplot, and/or macroplot). Divide the result by 4 to obtain change at the plot level.
10. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. 3. REGIONAL_DRYBIOT Regional dry total biomass (pounds). The total aboveground biomass of a sample tree 1.0 inch diameter or larger, including all tops and limbs (but excluding foliage). This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Calculated in oven-dry pounds per tree. This field should have an entry if DIA is 1.0 inch or larger, regardless of STATUSCD or TREECLCD; zero otherwise. For dead or cut trees, this number represents the biomass at the time of death or last measurement. Because total biomass has been calculated differently among FIA work units, contact the appropriate FIA work units (see table 6) for information on how biomass was estimated and whether bark was included.

REGIONAL_DRYBIOM
Regional dry merchantable stem biomass (pounds). The total gross biomass (including bark) of a tree 5.0 inches DBH or larger from a 1-foot stump to a minimum 4-inch top diameter of the central stem. This is a per tree value and must be multiplied by TPA_UNADJ to obtain per acre information. Calculated in oven-dry pounds per tree. This field should have an entry if DIA is 5.0 inches or larger, regardless of STATUSCD or TREECLCD; zero otherwise. For dead or cut trees, this number represents the biomass at the time of death or last measurement. Because total biomass has been calculated differently among FIA work units, contact the appropriate FIA work unit (see table 6) for information on how biomass was estimated and whether bark was actually included.
5. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY

MODIFIED_IN _INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. 3. EVALID Evaluation identifier. The EVALID code and the RSCD code together uniquely identify a set of field plots and associated Phase 1 summary data used to make population estimates.

Population Evaluation
4. EVAL_DESCR Evaluation description. A description of the area being evaluated (often a State), the time period of the evaluation, and the type of estimates the evaluation can be used to compute (i.e., all lands, area, volume, growth, removals, and mortality).

STATECD State code. Bureau of the Census Federal Information Processing Standards
(FIPS) two-digit code for each State. Refer to appendix C.

LOCATION_NM
Location name. Geographic area as it would appear in the title of a report.

REPORT_YEAR_NM
Report year name. The data collection years that would appear in the title of a report.

NOTES
Notes. Notes should include information about the stratification method. May include citation for any publications that used the evaluation. 9. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

START_INVYR
Start inventory year. The starting year for the data included in the evaluation.

END_INVYR End inventory year.
The ending year for the data included in the evaluation.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

EVAL_CN_FOR_EXPALL
Evaluation sequence number for expansions of all plots. This attribute links to the POP_EVAL.CN on the evaluation record. When this attribute is populated, it points to the evaluation used to estimate total area, including both sampled and nonsampled plots. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

EVAL_CN_FOR_EXPCURR
Evaluation sequence number for expansions of current area. This attribute links to the POP_EVAL.CN on the evaluation record. When this attribute is populated, it points to the evaluation used to estimate total area, using only sampled plots. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

EVAL_CN_FOR_EXPVOL
Evaluation sequence number for expansions of volume. This attribute links to the POP_EVAL.CN of the evaluation record. When this attribute is populated, it points to the evaluation used to estimate volume, biomass or number of trees, based on the sampled plots within the population that qualify for volume estimates. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

EVAL_CN_FOR_EXPGROW
Evaluation sequence number for expansions of growth. This attribute links to the POP_EVAL.CN of the evaluation record. When this attribute is populated, it points to the evaluation used to estimate net average annual growth, based on the remeasured plots within the population that qualify for growth estimates. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

EVAL_CN_FOR_EXPMORT
Evaluation sequence number for expansions of mortality. This attribute links to the POP_EVAL.CN of the evaluation record. When this attribute is populated, it points to the evaluation used to estimate average annual mortality, based on the remeasured plots within the population that qualify for mortality estimates. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

EVAL_CN_FOR_EXPREMV
Evaluation sequence number for expansions of removals. This attribute links to the POP_EVAL.CN of the evaluation record. When this attribute is populated, it points to the evaluation used to estimate annual removals, based on the remeasured plots within the population that qualify for removals estimates. Users must first obtain the correct sequence number in this attribute in order to run queries like those shown in chapter 4. This attribute will be dropped in version 5.0.

RSCD
Region or Station Code. Identification number of the Forest Service National Forest System Region or Station (FIA work unit) that provided the inventory data (see appendix C for more information). 9. EVAL_GRP Evaluation group. An evaluation group identifies the evaluations that were used in producing a core set of tables. In some cases one evaluation will be used for area and volume and another evaluation for growth, removals and mortality. The value of this attribute is used to select the appropriate State and year of interest to produce a set of summary tables.

EVAL_GRP_DESCR
Evaluation group description. A description of the evaluation group that includes the State and range of years for the evaluation, for example, " Minnesota: 1004;2006;2008". This is useful to include in a summary report to clearly identify the source of the data.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

NOTES
Notes. An optional item where additional information about the evaluation group may be stored.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
11. CN Sequence number. A unique sequence number used to identify a population evaluation type record

INVYR
Inventory year. The year that best represents when the inventory data were collected. Under the annual inventory system, a group of plots is selected each year for sampling. The selection is based on a panel system. INVYR is the year in which the majority of plots in that group were collected (plots in the group have the same panel and, if applicable, subpanel). Under periodic inventory, a reporting inventory year was selected, usually based on the year in which the majority of the plots were collected or the mid-point of the years over which the inventory spanned. For either annual or periodic inventory, INVYR is not necessarily the same as MEASYEAR.
Exceptions: INVYR = 9999. INVYR is set to 9999 to distinguish Phase 3 plots taken by the western FIA work units that are "off subpanel." This is due to differences in measurement intervals between Phase 3 (measurement interval = 5 years) and Phase 2 (measurement interval = 10 years) plots. Only users interested in performing certain Phase 3 data analyses should access plots with this anomalous value in INVYR.
INVYR <100. INVYR <100 indicates that population estimates were derived from a pre-NIMS regional processing system and the same plot either has been or may soon be re-processed in NIMS as part of a separate evaluation. The NIMS processed copy of the plot follows the standard INVYR format. This only applies to plots collected in the South (RSCD = 33) with the national design or a similar regional design (PLOT.DESIGNCD = 1 or 220-233) that were collected when the inventory year was 1998 through 2005. INVYR = 98 is equivalent to 1998 but processed through regional system INVYR = 99 is equivalent to 1999 but processed through regional system INVYR = 0 is equivalent to 2000 but processed through regional system INVYR = 1 is equivalent to 2001 but processed through regional system INVYR = 2 is equivalent to 2002 but processed through regional system INVYR = 3 is equivalent to 2003 but processed through regional system INVYR = 4 is equivalent to 2004 but processed through regional system INVYR = 5 is equivalent to 2005 but processed through regional system 10. EVALID Evaluation identifier. The EVALID code and the RSCD code together uniquely identify a set of field plots and associated Phase 1 summary data used to make population estimates.

ESTN_UNIT Estimation unit. A geographic area upon which stratification is performed.
Sampling intensity is uniform within an estimation unit.
12. STRATUMCD Stratum code. The code used for a particular stratum, which is unique within an RSCD, EVALID, ESTN_UNIT.
13. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.
14. CREATED_DATE Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN _INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
12. FOOTNOTE Footnote. Intentionally left blank. Will be populated in verion 5.0

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.
9. CN Sequence number. A unique sequence number used to identify a reference population evaluation type description record. 2. MEANING Meaning. The descriptive name corresponding with the forest type code (VALUE). The names associated with these codes are used to label rows or columns in National standard presentation tables. Refer to appendix D.

Reference Forest Type
3. TYPGRPCD Forest type group code. A code assigned to individual forest types in order to group them for reporting purposes. Refer to appendix D.

MANUAL_START
Manual start. The first version of the Field Guide (PLOT.MANUAL) that the forest type code (VALUE) began to be used.

MANUAL_END
Manual end. The last version of the Field Guide (PLOT.MANUAL) that the forest type code (VALUE) was valid. When MANUAL_END is blank (null), the code is still valid.

ALLOWED_IN_FIELD
Allowed in field. An indicator to show if a code (VALUE) is allowed to be used by the field crews. This is a Yes/No (Y/N) field. Specifically, forest type group codes are not allowed in the Field Guide nor is the code for a nonstocked forest type (VALUE = 999).
7 CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.  Jenkins and others (2003) equations are included in the REF_SPECIES table. Coefficients for calculating biomass components (stem wood, stem bark, foliage, coarse roots, stump, and sapling) are also included in the REF_SPECIES table. Biomass in branches and treetops (tops and limbs) may be found by subtracting the biomass in stem wood, stem bark, foliage, and stump from total aboveground biomass. Heath and others (2009) provides an overview of the historical use of Jenkins and others (2003) for biomass estimation for the U.S. forest greenhouse gas inventory (U.S. Environmental Protection Agency 2008) and an overview of the approach of the new biomass equations used for FIA data.

Reference Species
1. SPCD Species code. An FIA tree species code. Refer to appendix F for codes.

COMMON_NAME
Common name. Common name of the species. Refer to appendix F.
3. GENUS Genus. The genus name associated with the FIA tree species code. Refer to appendix F.

SPECIES
Species. The species name associated with the FIA tree species code. Refer to appendix F.

VARIETY
Variety. The variety name associated with the FIA tree species code.
6. SUBSPECIES Subspecies. The subspecies name associated with the FIA tree species code.

SPECIES_SYMBOL
Species symbol. The NRCS PLANTS database code associated with the FIA tree species code.
8. E_SPGRPCD Eastern species group code. A code indicating the species group assignment for eastern species. Depending on the State in which a tree is tallied, either the eastern or western species group code is associated with the actual TREE, SITETREE, and SEEDLING data. Species group codes and names can be found in appendix G.
9. W_SPGRPCD Western species group code. A code indicating the FIADB species group assignment for western species. Depending on the State in which a tree is tallied, either the eastern or western species group code is associated with the actual TREE, SITETREE, and SEEDLING data. Species group codes and names can be found in appendix G.

MAJOR_SPGRPCD
Major species group code. A code indicating the major species group, which can be used for reporting purposes. 27. WOODLAND Woodland. Indicates if the species is classified as a woodland species, meaning that the diameter is measured as root collar. Woodland species are marked with an X.

MANUAL_START
Manual start. The first version of the Field Guide (PLOT.MANUAL) that the species code was used.

MANUAL_END
Manual end. The last version of the Field Guide (PLOT. MANUAL) that the species code was valid. When MANUAL_END is blank (null), the code is still valid.
30. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CORE
Core. Indicates that the tree species must be tallied (measured) by all FIA work units. Species marked with a Y are core and core optional species are marked with an N.

JENKINS_SPGRPCD
Jenkins species group code. A code that identifies a group of similar species, which is used to apply the correct biomass estimation equation and coefficient developed by Jenkins and others (2003). A specific set of biomass equation coefficients are assigned to each group. Additional explanation about how to estimate biomass, and when to use a certain set of coefficients, is provided in appendix J.  Jenkins and others (2003). The appropriate coefficient to use is based on the species category (SFTWD_HRDWD). The stem is defined as that portion of the tree from a 1-foot stump to a 4-inch DOB top (i.e., the merchantable bole.) See appendix J for details on biomass equations. Jenkins stem wood ratio B2. A coefficient used in computing component ratio biomass. This is equivalent to coefficient B 1 for stem wood from table 6 in Jenkins and others (2003). The appropriate coefficient to use is based on the species category (SFTWD_HRDWD). The stem is defined as that portion of the tree from a 1-foot stump to a 4-inch DOB top (i.e., the merchantable bole.) See appendix J for details on biomass equations. Jenkins stem bark ratio B1. A coefficient used in computing component ratio biomass. This is equivalent to coefficient B 0 for stem bark from table 6 in Jenkins and others (2003). The appropriate coefficient to use is based on the species category (SFTWD_HRDWD). This ratio estimates bark biomass on the stem, defined as that portion of the tree from a 1-foot stump to a 4-inch DOB top (i.e., the merchantable bole.) See appendix J for details on biomass equations.
The average proportion of aboveground biomass in stem bark is calculated using this equation:

JENKINS_STEM_BARK_RATIO_B2
Jenkins stem bark ratio B2. A coefficient used in computing component ratio biomass. This is equivalent to coefficient B 1 for stem bark from table 6 in Jenkins and others (2003). The appropriate coefficient to use is based on the species category (SFTWD_HRDWD). This ratio estimates bark biomass on the stem, defined as that portion of the tree from a 1-foot stump to a 4-inch DOB top (i.e., the merchantable bole.) See appendix J for details on biomass equations.
The average proportion of aboveground biomass in stem bark is calculated using this equation:

JENKINS_SAPLING_ADJUSTMENT
Jenkins sapling adjustment factor. A factor used to compute the biomass of saplings. Sapling biomass is computed by multiplying diameter (DIA) by the appropriate species adjustment factor (from Jenkins and others [2003]). The sapling adjustment factor was computed as a national average ratio of the REGIONAL_DRYBIOT (total dry biomass) divided by the Jenkins total biomass for all 5.0-inch trees, which is the size at which biomass based on volume begins. Because this adjustment factor was computed at the species level, there is a specific adjustment factor for each species. Users can download the REF_SPECIES table, which includes the values of JENKINS_SAPLING_ADJUSTMENT at http://ncrs2.fs.fed.us/fiadb4downloads/datamart.html. See appendix J for details on biomass equations.

WOOD_SPGR_GREENVOL_DRYWT
Green specific gravity of wood (green volume and oven-dry weight). This variable is used to determine the oven-dry weight (in pounds) of live and dead trees based on volume variables in the TREE table (VOLCFSND, VOLCFGRS, VOLCFNET…). These volumes are assumed to be green wood volumes. Oven-dry biomass for the sound volume in a tree can be calculated using this equation: Where: B odw = sound oven-dry biomass of a tree in pounds VOLCFSND = sound volume of a tree in cubic feet

WOOD_SPGR_GREENVOL_DRYWT_CIT
Citation for WOOD_SPGR_GREENVOL_DRYWT. The value of this variable can be linked to the corresponding value in the CITATION_NBR variable in the REF_CITATION table to find the source of the WOOD_SPGR_GREENVOL_DRYWT variable.

BARK_SPGR_GREENVOL_DRYWT
Green specific gravity of the bark (green volume and oven-dry weight). There is some shrinkage in bark volume when a live tree is cut and dried. In FIADB, this specific gravity is used on live and dead trees to convert green volume to oven-dry weight in pounds. Oven-dry biomass for bark can be calculated using the volume of a tree using this equation: B odw = BARK_VOLUME x BARK_SPGR_GREENVOL_DRYWT x 62.4 Where: B odw = oven-dry biomass of bark on a tree in pounds BARK_VOLUME = volume of the bark on a tree bole, in cubic feet. Note that bark volume is often estimated by subtracting volume of the bole inside bark from volume of the bole outside bark. Or, an estimate of bark volume can be obtained using any tree volume column along with BARK_VOL_PCT found in this table as follows: BARK_VOLUME = TREE_VOLUME * (BARK_VOL_PCT/100.0)

BARK_SPGR_GREENVOL_DRYWT_CIT
Citation for BARK_SPGR_GREENVOL_DRYWT. The value of this variable can be linked to the corresponding value in the CITATION_NBR variable in the REF_CITATION table to find the source of the BARK_SPGR_GREENVOL_DRYWT variable.

MC_PCT_GREEN_WOOD
Moisture content of green wood as a percent of oven-dry weight. Wood and bark are often sold based on green weight. The user is cautioned that green weights can be extremely variable geographically, seasonally, within species and across various portions of individual trees.

MC_PCT_GREEN_WOOD_CIT
Citation for MC_PCT_GREEN_WOOD_CIT. The value of this variable can be linked to the corresponding value in the CITATION_NBR variable in the REF_CITATION table to find the source of the MC_PT_GREEN_WOOD variable.

MC_PCT_GREEN_BARK
Moisture content of green bark as a percent of oven-dry weight. Wood and bark are often sold based on green weight. The user is cautioned that green weights can be extremely variable geographically, seasonally, within species and across various portions of individual trees.

WOOD_SPGR_MC12VOL_DRYWT
Wood specific gravity (12 percent moisture content volume and oven-dry weight). Used in biomass estimation of forest products (lumber, veneer, etc.)

WOOD_SPGR_MC12VOL_DRYWT_CIT
Citation for WOOD_SPGR_MC12VOL_DRYWT. The value of this variable can be linked to the corresponding value in the CITATION_NBR variable in the REF_CITATION table to find the source of the WOOD_SPGR_MC12VOL_DRYWT variable.

BARK_VOL_PCT
Bark volume as a percent of wood volume. Bark volume expressed as a percent of wood volume. The volume of bark does not include voids due to ridges and valleys in bark.

BARK_VOL_PCT_CIT
Citation for BARK_VOL_PCT. The value of this variable can be linked to the corresponding value in the CITATION_NBR variable in the REF_CITATION table to find the source of the BARK_VOL_PCT variable.

RAILE_STUMP_DOB_B1
Raile stump diameter outside bark equation coefficient B1. This is equivalent to coefficient B from table 1 in Raile (1982). See appendix J for details on biomass equations.
This coefficient is used in an equation to estimate diameter outside bark at any point on the stump from ground to 1 foot high. From this, volume outside bark is estimated for the selected height along the stump. Volume inside bark is subtracted from volume outside bark to estimate bark volume. Both volumes are converted to biomass using either wood or bark specific gravities. (DOB and DIA are in inches, HT is in feet.) DOB = DIA + (DIA * RAILE_STUMP_DOB_B1 * (4.5-HT) / (HT+1))

RAILE_STUMP_DIB_B1
Raile stump diameter inside bark equation coefficient B1. This is equivalent to coefficient A from table 2 in Raile (1982). See appendix J for details on biomass equations.
This coefficient is used along with RAILE_STUMP_DIB_B2 in an equation to estimate diameter inside bark at any point on the stump from ground to 1 foot high. From this, volume inside bark is estimated for the selected height along the stump. Volume inside bark is subtracted from volume outside bark to estimate bark volume. Both volumes are converted to biomass using either wood or bark specific gravities. (DIB and DIA are in inches, HT is in feet.) DIB = (DIA * RAILE_STUMP_DIB_B1) + (DIA * RAILE_STUMP_DIB_B2 * (4.5-HT) / (HT+1))

RAILE_STUMP_DIB_B2
Raile stump diameter inside bark equation coefficient B2. This is equivalent to coefficient B from table 2 in Raile (1982). See appendix J for details on biomass equations.
This coefficient is used along with RAILE_STUMP_DIB_B1 in an equation to estimate diameter inside bark at any point on the stump from ground to 1 foot high. From this, volume inside bark is estimated for the selected height along the stump. Volume inside bark is subtracted from volume outside bark to estimate bark volume. Both volumes are converted to biomass using either wood or bark specific gravities. (DIB and DIA are in inches, HT is in feet.) DIB = (DIA * RAILE_STUMP_DIB_B1) + (DIA * RAILE_STUMP_DIB_B2 * (4.5-HT) / (HT+1)) Type of key Column(s) order Tables to link Abbreviated notation Primary (SPGRPCD) N/A SGP_PK 1. SPGRPCD Species group code. A code assigned to each tree species in order to group them for reporting purposes on presentation tables. Codes and their associated names (NAME) are shown in appendix G. Individual tree species and corresponding species group codes are shown in appendix F.

Reference Species Group
2. NAME Name. A descriptive name for each species group code (SPGRPCD). The names associated with these codes are used to label rows or columns in national standard presentation tables.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. 2. HABTYPCD Habitat type code. A code representing a habitat type. Unique codes are determined by combining both habitat type code and publication code (HABTYPCD and PUB_CD).

Reference Habitat Type Description
3. PUB_CD Publication code. A code indicating the publication that lists the name associated with a particular habitat type code (HABTYPCD).

SCIENTIFIC_NAME
Scientific name. This attribute contains some type of descriptor, usually the Latin name, of the plant(s) associated with the habitat type code. It has values such as the entire scientific name or the shortened synonym of the plant(s) represented by the habitat type code or it may have an English geographic type of descriptor.

COMMON_NAME
Common name. This attribute contains some type of descriptor, usually the common name, of the plant(s) associated with the habitat type code.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. Table (Oracle table name

CITATION
Citation. This attribute is usually a publication citation. In some cases CITATION may contain more specific information about how data were populated for a field.
3. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. 3. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

INSTALL_TYPE
Install type. Intentionally left blank. Will be populated in version 5.0. 3. MAX_ELEV Maximum elevation. The maximum elevation within the State in feet.

LOWEST_POINT
Lowest point. The name of the lowest point within the State. 'SL' refers to sea level. Negative minimum elevations are listed here.

HIGHEST_POINT
Highest point. The name of the highest point within the State. Alternative names are provided also. 6. CREATED_BY Created by. The employee who created the record. This attribute is intentionally left blank in download files.

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation. Table (Oracle table name

CREATED_DATE
Created date. The date the record was created. Date will be in the form DD-MON-YYYY.

CREATED_IN_INSTANCE
Created in instance. The database instance in which the record was created.
Each computer system has a unique database instance code and this attribute stores that information to determine on which computer the record was created.

MODIFIED_BY
Modified by. The employee who modified the record. This field will be blank (null) if the data have not been modified since initial creation. This attribute is intentionally left blank in download files.

MODIFIED_DATE
Modified date. The date the record was last modified. This field will be blank (null) if the data have not been modified since initial creation. Date will be in the form DD-MON-YYYY.

MODIFIED_IN_INSTANCE
Modified in instance. The database instance in which the record was modified. This field will be blank (null) if the data have not been modified since initial creation.

Chapter 4 -Calculating Population Estimates and Their Associated Sampling Errors
This chapter presents procedures written in Oracle™ SQL script that can be used to obtain population estimates (and associated sampling errors) for standard FIA attributes from the measurement data stored in the FIADB. These estimates follow the equations presented in Bechtold and Patterson (2005, chapter 4). Population estimates for many attributes can be generated using either the web-based EVALIDator tool or the Forest Inventory Data Online (FIDO) tool, which provides interactive access to the FIADB. These tools can be found at http://fia.fs.fed.us/tools-data.
All data stored in FIADB can be downloaded from http://fia.fs.fed.us/tools-data as either comma delimited files or Microsoft (MS) Access databases. Because of size limitations, data are stored in individual State databases. The SQL scripts used with MS Access differ from Oracle™ SQL scripts described in this chapter; however a number of MS Access queries are provided in the MS Access databases. All of the FIADB 4.0 tables are included in both formats. The MS Access databases have a few additional tables that make using the data and constructing queries easier and simpler. In addition, numerous queries that produce population estimates and standard errors are provided. Users can use these queries as a starting point to create customized queries suitable for local or regional analyses.
The FIADB can be used to estimate many attributes (e.g., forest area, timberland area, number of trees, net volume, biomass) from many different samples (typically State-wide inventories for a specific year or set of years). Therefore, the number of estimates that can be made from the FIADB is very large, and continues to increase as more data are added to the FIADB. This chapter provides examples of a few estimation procedures that can be modified by the user. The resulting estimates shown as output are examples only and are not necessarily the exact numbers a user will obtain using current data.
In addition to the naming conventions used in the FIADB, reference is made to the notation and terminology used in Bechtold and Patterson (2005). To fully understand the statistical basis of the estimation, readers may find it useful to refer to that publication as they review this chapter. Examples that estimate area of timberland, number of live trees on forest land, number of seedlings on timberland, and volume of growing-stock on timberland are presented, along with discussion of how these examples can be modified to estimate other attributes measured in Phase 2.
The basic estimation is broken down into four steps, with additional steps for users who want to go beyond the traditional population level estimates.
1. Selecting the attribute of interest (the quantity that is to be estimated).
2. Selecting an appropriate sample. 3. Linking the appropriate tables in the FIADB to produce estimates for attributes of interest for a population. 4. Producing estimates with sampling errors for attributes of interest for a population. 5. Restricting the attribute of interest to a smaller subset of the population (e.g., filtering the data to include only sawtimber stands on publicly owned timberland, versus all stands in all ownerships). 6. Changing the attribute of interest with user-defined criteria. 7. Estimating change over time on the standard 4-subplot fixed area plot.

Selecting the attribute of interest (using the REF_POP_ATTRIBUTE table)
The most common attributes of interest in FIADB estimation are described in the REF_POP_ATTRIBUTE table, which currently contains 92 entries. Attributes are currently defined at three levels (1) condition level attributes for area estimates; (2) tree level attributes for numbers of trees, volume, growth, removals, and mortality estimates; and (3) seedling level attributes for number of seedlings estimates. Estimation of condition level attributes requires accessing data on the PLOT and COND tables. Estimation of tree level attributes requires accessing data on the PLOT, COND, and TREE tables. Estimation of seedling level attributes requires accessing data on the PLOT, COND, and SEEDLING tables. Area sampled and denied access/hazardous (acres) 2 Area of forestland (acres) 3 Area of timberland (acres) 4 Number of all live trees on forestland (trees) 5 Number of growing-stock trees on forestland (trees) 6 Number of standing dead trees 5 inches+ dbh on forestland (trees) 7 Number of all live trees on timberland (trees) 8 Number of growing-stock trees on timberland (trees) 9 Number of standing dead trees 5 inches+ dbh on timberland (trees) 10 All live tree and sapling aboveground biomass on forestland oven-dry (short tons) 11 All live merchantable biomass on forestland oven-dry (short tons) 12 All live merchantable biomass on timberland oven-dry (short tons) 13 All live tree and sapling aboveground biomass on timberland oven-dry (short tons) 14 Volume of all live on forestland (cuft) 15 Volume of growing-stock on forestland (cuft) 16 Volume of sawlog portion on forestland (cuft) 17 Volume of all live on timberland (cuft) 18 Volume of growing-stock on timberland (cuft) 19 Volume of sawlog portion on timberland (cuft) 20 Volume of sawtimber on forestland (bdft) 21 Volume of sawtimber on timberland (bdft) 22 All live gross sawtimber volume on forestland (bdft) 23 All live gross volume on forestland (cuft) 24 All live sound volume on forestland ( 1,2,3,4,5,6) a Note that for Microsoft Access SQL, the decode function is replaced with the IIF function EXPRESSION is multiplied by the expansion factor POP_STRATUM.EXPNS and summed at the condition level in the estimation procedure. In the notation used in Bechtold and Patterson (2005), this sum is P hid for area estimation (see equation 4.1, page 47) or y hid for the estimation of tree attributes (see equation 4.8, page 53). In all cases, EXPRESSION consists of the product of two terms, the first term (c.condprop_unadj, t.tpa_unadj, and s.tpa_unadj in our examples) is the unadjusted observation of the attribute of interest (on a per acre basis). The second term is the appropriate stratum adjustment factor. The stratum adjustment factor is the inverse of the mean proportion of the sample plot areas that were within the population. Following the notation of Bechtold and Patterson (2005) this adjustment factor is mh p 1 (see equation 4.2, page 49). The decode statement simply selects the appropriate adjustment factor to be used for the specific estimate. Area estimates use either ADJ_FACTOR_MACR (in inventories where area estimates are based on the macroplot) or ADJ_FACTOR_SUBP (in inventories where area estimates are based on the subplot) for the adjustment. The adjustment of tree-and seedling-level estimates is based on the plot on which the tree or seedling was sampled (seedlings and trees <5 inches diameter are sampled on the microplot, larger trees are sampled on the subplot or macroplot depending on diameter).
Common selection criteria used often with FIA data when creating queries include various classifications of land and groups of trees as shown below:

Identifying land classes (COND table):
Identifying tree characteristics:

Selecting an appropriate sample (using the POP_EVAL_GRP, POP_EVAL, and POP_EVAL_TYP tables)
In order to compute a sample-based population estimate, the appropriate sample and stratification must be identified. In FIA estimation, the sample is a set of plots that were selected for the attribute of interest that was observed. The stratification consists of an assignment of plots to strata (nonoverlapping areas of a known or estimated size) that in aggregate define the population of interest.
There is an assignment of plots to every stratum, and all plots are assigned to one, and only one stratum, for each evaluation. FIA uses the term "evaluation" to reference the relationship that links a set of plots to a set of strata for estimation purposes. Thus, an evaluation is a set of plots defined in the FIADB that can be used to make a statistically valid sample-based estimate for a population (area of land) based on a specific stratification.
Each evaluation used by FIA is identified, named, and stored as a single entry in the POP_EVAL  In the POP_EVAL_GRP table the data item EVAL_GRP identifies the evaluation group by its State code (first 2 digits) and a year (last 4 digits), which is the year commonly associated with estimates (if EVAL_GRP does not follow this format, see the EVAL_GRP_DESCR for the precise identification). In table 4.4 we see evaluation groups for two periodic inventory estimates (1977 and 1990), and four annual estimates (2003, 2004, 2005 and 2006). The EVAL_GRP_DESCR describes the groups, and indicates that all of the annual inventory estimates are based on 5 years of measurements taken over the 5-year period ending with that date. The data items EVAL_CN_FOR_EXPALL, EVAL_CN_FOR_EXPCURR, EVAL_CN_FOR_EXPVOL, EVAL_CN_FOR_EXPGROW, EVAL_CN_FOR_EXPMORT, and EVAL_CN_FOR_EXPREMV identify the evaluations in POP_EVAL that are appropriate for the estimation of various attributes of interest. EVAL_CN_FOR_EXPCURR identifies the evaluation used in the estimation of most area estimates, such as the area of forestland or the area of timberland. EVAL_CN_FOR_EXPVOL identifies the evaluation used in the estimation of tree-level attributes such as number, volume, and biomass of trees, and seedling-level estimates, such as number of seedlings. EVAL_CN_FOR_EXPGROW, EVAL_CN_FOR_EXPMORT, and EVAL_CN_FOR_EXPREMV identify the evaluations used in the estimation of growth, mortality, and removals, respectively. The evaluation identified by EVAL_CN_FOR_EXPALL is only appropriate for area estimation where the area of hazardous and denied access are of interest. All other evaluations treat hazardous and denied access as non-measured and adjust the estimate to account for these areas.
The POP_EVAL_TYP table was added to the FIADB in the transition from version 3.0 to 4.0 to provide a link between the evaluation groups in POP_EVAL_GRP and the evaluations in POP_EVAL. In FIADB 3.0, users could select the appropriate evaluation sequence number (EVAL_CN_FOR_xxx) from the POP_EVAL_GRP table. This evaluation sequence number allowed them to select the appropriate plots and associated expansions. Evaluations are now also identified by the type of evaluation in the value of POP_EVAL_TYP.EVAL_TYP, which can take on values of "EXPALL," "EXPCURR," "EXPVOL," "EXPGROW," "EXPMORT," or "EXPREMV" to identify the type of attributes that can be estimated from a specific evaluation. This table allows users to perform similar queries on the appropriate evaluation by identifying only the eval_grp (STATECD*10000 + INV_YR) and evaluation type (EVAL_TYP) and allows a variety of evaluations to be added in the future. The methods used in version 3.0 will continue to work in version 4.

Linking the appropriate tables in FIADB to produce estimates of attributes of interest for a population
The following Oracle™ SQL script can be modified to produce an estimate of any condition-, tree-, or seedling-level attribute listed in the REF_POP_ATTRIBUTE Estimation requires linking the attribute values (on the COND, TREE, and SEEDLING tables) to the stratification information (on the POP_PLOT_STRATUM_ASSGN, POP_STRATUM, and POP_ESTN_UNIT) for the selected evaluation that defines the sample. Those links are provided in lines 15 thru 20 of the script, and these lines do not change. Line 15 links the POP_PLOT_STRATUM_ASSGN record (which contains EXPNS, the plot expansion factor or acres assigned to the plot) to the plot record. Line 16 links the POP_PLOT_STRATUM_ASSGN record to the POP_STRATUM (which identifies each stratum in the estimation unit). Line 17 links the POP_ESTN_UNIT (which identifies each estimation unit in the evaluation) to the POP_ STRATUM record. Line 18 links the POP_EVAL, which identifies each evaluation, to the specific evaluation that is required for the estimation. Lines 19 and 20 link the appropriate evaluation to the attribute and evaluation group for which the estimate is being made. See figure 6 for a schematic of links of some of the FIADB tables.
The following table shows some common aliases or abbreviations used within a SQL script to reduce the overall length of the script and improve readability. In the following four examples (4.2, 4.3, 4.4, and 4.5), the scripts are modified from above to produce condition, tree, and seedling level estimates for the    (1, 2, 3, 4, 5, 6) AND t.statuscd = 1 AND t.treeclcd = 2 AND t.dia >= 5.0 --additional where_clause from ref_pop_attribute table AND ppsa.plt_cn = p.cn AND ppsa.stratum_cn = psm.cn AND peu.cn = psm.estn_unit_cn AND pev.cn = peu.eval_cn AND pev.cn = pet.eval_cn AND pet.eval_grp_cn = peg.cn AND peg.eval_grp = 272003 --the desired evaluation group must be specified Produces the following estimate of total growing-stock volume (cubic feet) on timberland: ESTIMATE 15,242,634,295 Users of the FIADB who wish to produce population estimates should test these four examples to be sure they are obtaining identical estimates before proceeding to more complicated estimation. Important Note: Users who access data from periodic inventories should restrict the estimation only to the standard timberland estimates. In most cases, for periodic inventories, the FIADB contains only condition level information on reserved and unproductive forest lands, and tree level information on timberland.

Changing the attribute of interest with user-defined criteria
Users can define condition level attributes of interest. The standard condition level attributes of interest are sampled land area and all land area (expressed in acres). Sampled land area (adjusted for denied access and hazardous conditions that were not sampled) is the one used for nearly all standard FIA tables that report area estimates. All land area (where denied access and hazardous are considered part of the sample) is only used in estimation that treats denied access (plots on land where field crews were unable to obtain the owner's permission to measure the plot) and hazardous (conditions that were deemed too hazardous to measure the plots) as part of the sample attribute of interest. Most of the other condition level variables that FIA observes are typically used to categorize the condition, and are most often applied as restrictions on the population in defining the domain, and do not lend themselves as an attribute of interest. For example, BALIVE (the basal area of live trees 1 inch diameter and larger) is mainly used to categorize forest land area rather than as an attribute of interest in population level estimation. Users are more interested in knowing how many acres of forest land meets some basal area requirement (say between 50 and 100 square feet per acre), rather than the total basal area of forest land in a State.
An example of a user-defined condition level attribute of interest, for which an estimate of a total might be of interest, would be total land value (see Example 4.11). Here the user would supply a function that assigns value ($ per acre) to forest land, based on attributes in FIADB. As an example, we use a very arbitrary function of site index and basal area of live tree -value per acre = 1000 + (site index x 3) + (basal area x 4), and limit the domain of interest to only private timberland. Modifying example 1 produces the following script and estimate of total value. Since the function is a condition level value per acre, it is simply included in the expression as a multiplication factor, and the domain restriction (private timberland) is added to the where clause. The sections that have been added to example 4.2 are in boxes. The same modifications were added to example 4.7 to produce the estimates with sampling errors. Based on this function, the estimated total value of private timberland in the State is 10.1 billion dollars. This value function is used only as an example, any type of user defined function that assigns quantities, such as value ($ per acre), wildlife population level (animals per acre), productivity (yield per acre), or carbon sequestration potential (tons per acre) could be used as long as it is a function of data items in the FIADB, and/or data attributes from other sources that can be linked to FIA plots.

Estimates of change over time on the standard 4-subplot fixed area plot
A number of the attributes described in the REF_POP_ATTRIBUTE table are related to change over time and are based on computed attributes that utilize data from two points in time from the same plot. The attributes identified by values 25-44 (e.g., net growth of all live on forestland represented by 25) of REF_POP_ATTRIBUTE.ATTRIBUTE_NBR are the standard growth, removals and mortality attributes that FIA presents in its reports. The computation of these values as presented in the previous section will provide estimates of these change attributes; however, all estimation is done through the observations made and recorded at the second measurement of the plot. Users often wish (1) to obtain estimates that reflect changes in attributes over the remeasurement of the plot that go beyond these attributes, (2) to classify these standard estimates and other estimates by attributes from the previous measurement, or (3) to cross classify them by changes in various attributes over time. Examples of these types of estimations are: • Breakdowns of change in area over time by past and current land use, forest type, or other condition attributes. • Number of trees on forest land that changed to nonforest land.
• Removals of trees on forest land of a specific forest type that changed to a different forest type after removals. • Mortality of trees that were in a specific diameter range in the previous measurement.
• Change in the number of seedlings per acre over time for a specific forest type.
The estimation of these and many other change attributes require properly selecting the appropriate set of plots that were measured at both points in time and linking data from these two measurements.
Prior to 1999, FIA used periodic inventories with different plot designs. Since 1999, the new annual inventory uses a national standard, 4-subplot fixed area plot design. The change estimation procedures described here are applicable to all plots measured at least twice in the annual inventory, but may not be appropriate for change estimation between periodic and annual inventories.

Selecting an appropriate set of plots (evaluation) for change estimations
For change estimation, select an evaluation that consists of only remeasured plots, evaluations used for growth, removals, and mortality estimation. These growth-removals-mortality (GRM) evaluations can be identified by either of the following restrictions in the where clause: and pop_eval.cn = pop_eval_grp.eval_cn_for_expgrow, or and pop_eval_typ.eval_grp_cn = pop_eval_grp.cn and pop_eval_typ.eval_typ = 'EXPGROW' Either of these statements will restrict the sample plots to only those used in the estimation of growth: only the set of plots that have been measured at two points in time.
In the examples we continue linking to evaluations through the POP_EVAL_TYP table (second example).

Linking tree level data to past condition data
In the following examples, we demonstrate how to produce a tree-level estimate (net growth of all live trees on forest land), and then link it to conditions at two points in time (past and current) to produce a table that breaks down the estimate by condition-level attributes and the two points in time.
First we begin with the script that produces an estimate of total net growth of all live trees on forest land for the 2007  We then modified this example to link not only to the condition record at the current (second) measurement, but also to the condition record at the previous (first) measurement by using the attribute TREE.PREVCOND to link each tree record to its previous condition. We also added a group by clause to produce the estimates broken down by values of the condition level attributes COND_STATUS_CD (condition status code) and STDSZCD (stand-size class code) at both points in time. This procedure is shown in example 4.13, which was created by adding the bold sections to example 4.12.
Example 4.13 Estimate net growth of all live on forest land (cubic feet per year) by condition status and stand size at two points in time. The following tabulation of estimated net growth on forest land by condition status code and stand-size class at the two points in time can be made from the example 4.13 results. Note that we have added the code labels to the row and column headings, and each cell in the tabulation is the appropriate value from example 4.13. Estimated total net growth of all live trees on forest land broken down by past and current condition status code and stand-size class, Minnesota, 2007 (cubic feet per year).

The SUBP_COND_CHNG_MTRX (CMX) table
The SUBP_COND_CHNG_MTRX (CMX) table was added in the FIADB version 4.0 to facilitate the tracking of area change for the annual inventory. Under this design, a plot measures area change by tracking the movement in condition boundaries within the area of the four subplots. Figure 7 shows what can happen on a plot when a condition boundary (in this case the edge of a beaver pond) moves over time. Beaver activity raised the level of the pond, increasing the pond area and converting some of the forest land to water. The same kind of changes can occur from any number of human-caused events such as timber harvesting, land clearing or road construction, or natural events such as fire, storms, or insect attacks.
It is important to remember that condition boundaries are not just defined along changes in condition status code, but also may occur within forest land. The following tabulation shows how the area change information in figure 7 would be recorded in the CMX  The CMX table tracks the change in condition areas for each of the four subplots (SUBPTYP = 1) and each of the four microplots (SUBPTYP = 2) on this plot. In inventories where the macroplot is used there would also be entries for each macroplot (SUBPTYP = 3). The attribute PROP_BASIS in the COND table identifies how area estimation was conducted for each plot, on the basis of either the macroplot or the subplot. In this example area estimation (and thus area change estimation) is based on the subplot information, not the macroplot. Area estimation is typically based on the largest area sampled (macroplot in States where it is measured, otherwise the subplot) and not on the microplot. Area and area change estimation based on the microplot is only appropriate with another estimate solely collected on the microplot such as number of trees or biomass in trees <5 inches diameter at breast height. The examples of change presented here are based on the subplot, but could easily be modified to obtain estimates based on the microplots.
In the example shown in figure 7, the CMX table has two entries where SUBPTYP = 1 and SUBP = 1. The first entry indicates that 80 percent of the subplot area was in condition 1 (water) at both measurements, and the second entry indicates 20 percent of the subplot area changed from forest to water. For the other three subplots and all four microplots, only one record exists, indicating that the entire subplot or microplot either stayed in the same condition (subplots and microplots 2 and 3) or the entire area changed from one condition to another (subplot and microplot 4). For this remeasured plot, change based on the four subplots is water to water 45 percent, forest to water 30 percent, and forest to forest 25 percent; change based on the four microplots is water to water 50 percent, forest to water 25 percent, and forest to forest 25 percent. The following section presents SQL script that produces these estimates.

Using the CMX table to estimate area change between two measurements
The estimation of area change over time requires linking past and current conditions through the CMX table to determine the portion of plot area that transitioned from conditions observed at time 1 to those observed at time 2 (methods applicable only between two measurements in the annual inventory). As in examples 4.12 and 4.13, select an evaluation that consists of only remeasured plots. In the examples that follow, we show how to create area change estimates that go with the net growth of all live trees on forest land as obtained from example 4.13.
We begin by modifying the script that produces the estimate of area of forest land so that it uses the net growth evaluation EXPGROW rather than the area evaluation EXPCURR that is standard for area estimations. Example 4.14 shows this modification in bold.
Example 4.14 Estimate area of forest land (acres) based on the net growth evaluation. The remeasured plots (12,280 plots) associated with EXPGROW produce an area estimate of 16,962,397.2 acres of forest land versus 16,723,532.5 provided by EXCURR using all plots (17,855 plots). Both estimates of forest area are valid; however, only the one based on the remeasurement sample can be broken down into two points in time.
To estimate area change over time, the script has been further modified to link past and current condition records through the CMX table. This table has entries for every subplot on a remeasured plot and stores the proportion of the area of each subplot by the two points in time in the attribute CMX.SUBTYP_PROP_CHNG. Example 4.15 shows the script that produces the area change estimates that go with the net growth estimates produced in example 4.13. Again, changes and additions from example 4.14 are shown in bold. Line numbers are for reference purposes. Example 4.15 can be used as a template to create almost any cross tabulation of past and current area estimates based on a remeasured set of plots. The following changes (bold sections) were made to example 4.14 to facilitate the estimation of area change: • Line 21 -The table COND with the alias C_PAST was added to the list of tables to be joined. This provides the condition level attributes for the past (time 1) measurement of the plot.
• Line 22 -The table SUBP_COND_CHG_MTRX with the alias CMX was added to the list of tables to be joined. This table provides the link between past (time 1) and current (time 2) conditions at the subplot level. Each entry in this table defines the portion (0-1) of the subplot, microplot or macroplot that was observed in a condition at time 2 and observed in a condition at time 1. For a subplot that was entirely in a single condition at both times, there will only be one entry for the subplot, with CMX.SUBPTYP_PROP_CHNG = 1.0. For a subplot that was mapped to be 40 percent in one condition and 60 percent in another condition at both times with no change in boundary, there will be two entries for the subplot, one with CMX.SUBPTYP_PROP_CHNG = 0.4 and the other with CMX.SUBPTYP_PROP_CHNG = 0.6. For subplots where boundaries have changed, there will be entries that account for all the pieces of the subplot area with the total value of CMX.SUBPTYP_PROP_CHNG adding to 1.0.
• Line 5 -c.condprop_unadj (the total plot condition proportions that are within a specific condition) was replaced with cmx.subptyp_prop_chng / 4 (the subplot condition proportion divided by the number of subplots in the plot). The division by 4 is required because the CMX table tracks area at the subplot level (4 subplots per plot).
• Line 25 -The restrictions were changed in the where clause from AND c.cond_status_cd = 1 to AND (c.cond_status_cd = 1 or c_past.cond_status_cd = 1), to select conditions that were forest in at least one of the measurements, not just the current measurement. This query tracks the area of land that moves in and out of forest, as well as changes in stand-size class on land that remains forest.
• Lines 33-38 -These additions to the where clause provide the proper links to the C_PAST and CMX tables that were added to the table list. Line 33 (AND p.prev_plt_cn = c_past.plt_cn) matches the past and current condition records to the same plot, and lines 34-38 provide the other restrictions that link the appropriate conditions at the two measurements through the CMX table. Lines 37 and 38 ensure that in inventories where area estimates are based on the macroplot observations, the area change estimates are based on the macroplot observations, and in all other cases the estimates are based on the subplot observations.
COUNT is the total number of subplot pieces that is tracked in the estimation. PLOT_AREA is the total portion of plots that is tracked in the estimation.
Example 4.15 produces the following estimates of total area (ESTIMATE), total number of subplots (COUNT), and total portion of plots (PLOT_AREA) broken down by past and current COND_STATUS_CD and STDSZCD values, for land that was forest at measurement time 1, measurement time 2, or both. These results are used to produce the following tabulation of estimated change in forest area by condition status code and stand-size class at two points in time.  IN (3,4)):

325
Ten variable-radius, 37.5 BAF points, 70 feet apart, for trees ≥5 inches DBH and 10, 1/300 acre plots for seedlings and trees ≥1 and <5 inches DBH. Point and plot center were coincident. Conditions were not mapped. Instead, points were rotated into forest or nonforest based on the condition at point center.

327
Ten variable-radius, 37.5 BAF points, 70 feet apart, for trees ≥5 inches DBH and 10, 1/300 acre plots for seedlings and trees ≥1 and <5 inches DBH. Point and plot center were coincident. Conditions were not mapped. Instead, points were rotated into forest or nonforest based on the condition at point center. Diameters were estimated with a model, but all dead and cut trees were recorded.

FIA work unit
Plot design code (DESIGNCD)

Appendix J. Biomass Estimation in the FIADB
In previous versions of the FIADB, a variety of regional methods were used to estimate tree biomass for live and dead trees in the TREE table. In FIADB 4.0, a new nationally consistent method of estimating tree biomass has been implemented. This new approach, called the component ratio method (CRM) (Heath and others 2009), involves calculating the dry weight of individual components before estimating the total aboveground or belowground biomass. The CRM approach is based on: • converting the sound volume of wood (VOLCFSND) in the merchantable bole to biomass using a compiled set of wood specific gravities (Miles and Smith 2009) (see REF_SPECIES table for values) • calculating the biomass of bark on the merchantable bole using a compiled set of percent bark estimates and bark specific gravities (Miles and Smith 2009) (see REF_SPECIES table for values) • calculating the biomass of the entire tree (total aboveground biomass), merchantable bole (including bark), and belowground biomass, using equations from Jenkins and others (2003) • calculating the volume of the stump (wood and bark) based on equations in Raile (1982) and converting this to biomass using the same specific gravities used for the bole wood and bark • calculating the top biomass (tree tip and all branches) by subtracting all other biomass components from the total aboveground estimate • calculating an adjustment factor by developing a ratio between bole biomass calculated from VOLCFSND to bole biomass using equations from Jenkins and others (2003) • applying the adjustment factor to all tree components derived from both Jenkins and Raile The CRM approach is based on assumptions that the definition of merchantable bole in the volume prediction equations is equivalent to the bole (stem wood) in Jenkins and others (2003), and that the component ratios accurately apply.
The tables in this appendix describe the equations used in FIADB 4.0 to estimate components of tree biomass, including stem wood (bole), top and branches combined, bark, stump, and coarse roots. Most of these components are estimated through a series of ratio equations as described by Jenkins and others (2003). Stem wood biomass is calculated directly from the sound cubic-foot volume of the tree bole, percentage of bark on the bole, and specific gravities of both wood and bark.
The individual component biomass values for bole, top, and stump are not available in FIADB for sapling-size timber tree species and all woodland tree species. Because saplings (trees from 1 to 4.9 inches in diameter) have no volume in FIADB, a ratio method was developed to compute a factor that is applied to saplings based on diameter and species, and the result is stored in DRYBIO_SAPLING. For woodland species (trees where diameter is measured at the root collar [DRC]), volume is calculated from the root collar to a 1½-inch top diameter. Because this volume accounts for a larger portion of the tree than timber species volume equations do, it was determined that the top and stump equations were not applicable to woodland species. Woodland tree volume is converted to biomass and stored in DRYBIO_WDLD_SPP, which is an estimate for total aboveground biomass, excluding foliage, the tree tip (top of the tree above 1½ inches in diameter), and a portion of the stump from ground to DRC. Therefore, only total aboveground and belowground biomass values are estimated for saplings and woodland species.
Definitions of each biomass component and the equations used to estimate the oven-dry weight in pounds are shown in appendix tables J-1 through J-4.

DRYBIO_BOLE
(wood and bark) (see note below) (timber species only) VOLUME = VOLCFSND (or VOLCFGRS, VOLCFNET that are adjusted for the percent sound) Volume = includes the volume of wood from a 1-foot stump to a 4-inch top diameter = (VOLUME * (BARK_VOL_PCT / 100.0) * (BARK_SPGR_GREENVOL_DRYWT * 62.4) ) + (VOLUME * (WOOD_SPGR_GREENVOL_DRYWT * 62. For woodland species, volume equations produce volume of wood and bark, from DRC to a 1½-inch top diameter, and includes branches. Biomass equations for each component are not available, therefore stem volume is converted to biomass and stored in DRYBIO_WDLD_SPP. This is an estimate of total aboveground biomass for woodland species, which includes wood and bark for the stem and branches and excludes foliage, the tree tip (top of the tree above 1½ inches in diameter), and a portion of the stump from the ground to the point of diameter measurement. For trees with a DRC ≥5 inches: VOLUME = VOLCFSND (or VOLCFGRS, VOLCFNET that are adjusted for the percent sound) VOLUME = includes the volume of wood, bark, and branches Wood and bark volumes need to be separated before converting to biomass as follows: = (VOLUME * (BARK_VOL_PCT / 100.0) * (BARK_SPGR_GREENVOL_DRYWT * 62.4)) + ((VOLUME -(VOLUME * (BARK_VOL_PCT / 100.0))) * (WOOD_SPGR_GREENVOL_DRYWT * 62.4)) For trees with a DRC <5 inches: = (total_AG_biomass_Jenkins -foliage_biomass_Jenkins) * JENKINS_SAPLING_ADJUSTMENT

Column name Equation (refer to Appendix table J-3 for details on variables found in equations below)
DRYBIO_BG (timber and woodland species) = root_biomass_Jenkins * AdjFac (for timber spp ≥5 inches DBH) = root_biomass_Jenkins * JENKINS_SAPLING_ADJUSTMENT (for timber species <5 inches DBH) = root_biomass_Jenkins * AdjFac_woodland (for woodland species ≥1 inch DRC) Note: If DIA ≥ 5.0 and VOLCFSND >0 then VOLUME = VOLCFSND If DIA ≥ 5.0 and VOLCFSND = (0 or null) and VOLCFGRS >0 then VOLUME = VOLCFGRS * Percent Sound If DIA ≥ 5.0 and VOLCFSND and VOLCFGRS = (0 or null) then VOLUME = VOLCFNET * (Average ratio of cubic foot sound to cubic foot net volume, calculated as national averages by species group and diameter) FIA Database Description and Users Manual for Phase 2, version 4.0 Appendix J