Fig 1.
Susquehanna Shale Hills Critical Zone Observatory macroplot site map.
Elevation map of Susquehanna Shale Hills Critical Zone Observatory with included topographical contoured lines. White, red, green, and blue dots represent macroplot sites that were established at ridge top, mid-slope planar, swale, and valley floor locations, respectively. Cyan diamonds represent macroplot volumetric time domain reflectometry (TDR) sensors locations, 2–3 per plot. TDR observations were also taken at sites with previously installed soil moisture sensors termed “GroundHOG” sites, which were represented on the map as asterisks. GroundHOG stands for ground hydrologic observation gear. GroundHOG sites have additional gas, water and measuring sensors used by the SSHCZO that were not used in this study.
Fig 2.
Survivorship of roots at different topographic locations.
Survivorship curve of first-order roots in the top 10 cm of soil born in the spring of 2017 at different topographic regions, specifically ridge top (RT), midslope planar (MSP), swale (SW), and valley floor (VF) locations.
Table 1.
Topographic proportional hazards table for different years and seasons.
Fig 3.
Survivorship of roots at different depths and topographic locations.
(a) Survivorship curves of first-order roots at different soil depths born in the fall of 2017 at swale locations. (b) Survivorship curves of first-order roots at different soil depths at valley floor (VF) and midslope planar (MSP) locations.
Fig 4.
Influence of soil series on root survivorship in midslope locations.
Survivorship curves of first-order roots in the top 10 cm of soil born in the spring of 2018 across soils on the north slope with different slope steepness, specifically: Steep Weikert (Steeper (MSP)), flatter Weikert (Flatter (MSP)), and Rushtown (Swales).
Table 2.
Mid-slope soil series proportional hazards table for different years and seasons.
Fig 5.
Seasonal trends in first-order root lifespan across the Susquehanna Shale Hills Critical Zone Observatory.
Bayesian regression models were used in kriging. Maps displayed are posterior means of days since first appearance of a root in the upper 10 cm of soil. Number of plots with at least ten roots produced (n≥10) that were used in kriging were as follows: Spring 2017 (13 plots), summer 2017 (35), fall 2017 (25), spring 2018 (9), summer 2018 (38), and fall 2018 (27).
Table 3.
Proportional hazards table for the effect of aspect (south or north facing) on root survivorship in different years and seasons.
Table 4.
Season of birth proportional hazards table for different years.