Fig 1.
Study area: Delong Mountain Transportation System haul road and Cape Krusenstern National Monument, Alaska.
Thirty-two km of the haul road traverses an industrial easement through the monument. Geographic coordinates are N for latitude and W for negative longitude. Congress granted the Northwest Alaska Native Association (NANA) an easement through the monument in 1985. NANA retained ownership of lands including the Port Site located within the monument boundary.
Fig 2.
Sample plot locations in Cape Krusenstern National Monument, Alaska.
Plots were arrayed at distances of 10, 50, 100, 300, 1000, 2000, and 4000 m from the DMTS haul road using GIS-based haul road buffers at those distances. Autocorrelation plots were 10–20 m from selected transect plots in the 1000–4000 m distance classes.
Table 1.
Mean values of important co-variates at the full range of distance classes from the DMTS haul road in CAKR, with the standard error of the mean (presented in parentheses).
Mean elemental values are mg/kg in Hylocomium splendens tissue, dry weight, except % Total S and % Total N. Values are presented for the Reference Sites and the Kotzebue road sites that were not included in subsequent analyses of vegetation community structure. The 2001 values for Cd, Pb and Zn are from Hasselbach et al. [18].
Fig 3.
Lichen species richness versus the log10 of distance to the DMTS haul road in Cape Krusenstern National Monument, Alaska.
Lichen species richness in 94 vegetation plots (4 x 8 m) between 10–4000 m from the road, Cape Krusenstern National Monument, Alaska.
Fig 4.
Nonmetric multidimensional scaling ordination of lichen plots at distances 10 m through 4000 m from the DMTS haul road in Cape Krusenstern National Monument, Alaska.
The ordination is overlain by vectors proportional to the strength of their correlation with ordination axes. Spearman r values for each variable are provided in Table 2. Convex hulls surround plots in each distance class. All two letter abbreviations are elements. Mean elemental values in the data were mg/kg in Hylocomium splendens tissue, dry weight, except % Total S and % Total N. Other abbreviations are: Total_S (total sulfur), LSR (lichen species richness), LogDist_Rd (log10 distance to the haul road), Total_N (total nitrogen), P (phosphorus), Dist_Rd (distance to the haul road).
Table 2.
Spearman correlation coefficients (r) of environmental variables for two NMS ordinations on transect plots out to 4000 m from DMTS haul road in CAKR: Lichen ordination (91 plots x 93 species) and bryophyte ordination (91 plots x 5 species groups).
Values for which r > 0.5 are presented in bold.
Fig 5.
Photos of Hylocomium splendens moss and Peltigera sp. lichen from 10 m vs 4000 m away from the DMTS haul road in Cape Krusenstern National Monument, Alaska.
Photos a, b: H. splendens. Photos c,d: Peltigera sp. Photos were taken in the lab using dried materials.
Table 3.
Number of indicator species analysis p values < 0.05 in the 7 distance classes from the DMTS haul road in CAKR.
Table 4.
MRPP A-statistics from pairwise comparisons plot distance classes for lichen, vascular plant and bryophyte communities.
Color shadings reflect groupings of strong (red), moderate (yellow) and weak (blue) or little (black) community differences. Community differences were evaluated using Sorenson distance measure on log10 transformed matrices of: lichens (91 plots x 93 species), vascular plants (91 plots x 56 species) and bryophytes (91 plots x 5 species groups).
Fig 6.
Estimated mean lichen species richness vs. distance to the DMTS haul road in Cape Krusenstern National Monument, Alaska, on a log-log scale from a Bayesian posterior predictions model.
The 95% confidence interval is shown in grey.
Fig 7.
Modeled lichen species richness in a prediction grid from 0 to 4000 m from the DMTS haul road in Cape Krusenstern National Monument, Alaska.
Prediction grid points are limited to those in the same land cover types as the study plots, as other land cover types have different lichen diversity and cover. Road buffer lines are drawn at 10, 50, 100, 300, 1000, 2000 and 4000 m. Points are sized proportionally in four classes by the quartile distributions of the reciprocal of the coefficient of variation (CV). The upper and lower bounds of the 95% confidence interval (i.e., 97.5 and 2.5 percentile values of the 200 simulations) are provided in small maps below the main map.
Table 5.
Lichen species richness (LSR) model summarized by distance class from the DMTS haul road in CAKR.
Summarization methods for mean, standard error (SE), minimum, maximum, 2.5 percentile, 97.5 percentile and probability of decrease (Pr Decrease) follow those used in Neitlich et al. [17] for contaminants. The probability of decrease (Pr Decrease) reports the percentage of decreases in the comparisons of the 200 posterior predictions of each adjacent distance class.
Table 6.
Area estimates in CAKR by percentage of the mean LSR of the 3000–4000 m distance class (41.9) according to the posterior predictions model.
The areas represented here are only those within the study area (i.e., within a 4000 m buffer of the DMTS haul road and on NPS lands).
Fig 8.
Nonmetric multidimensional scaling ordination of vascular plants in a matrix of 93 plots x 36 species along the DMTS haul road in Cape Krusenstern National Monument, Alaska.
The ordination is overlain by vectors proportional to the strength of their correlation with ordination axes. Convex hulls surround plots in each distance class. Variables with Spearman correlations r > 0.4 are presented: LogDist_Rd (log10 distance to the road), Vascular Species Richness (VPSR), and modeled Cd, Pb and Zn from 2001 [18].
Fig 9.
Nonmetric multidimensional scaling ordination of bryophytes on a matrix of 94 plots by 5 species groups along the DMTS haul road in Cape Krusenstern National Monument, Alaska.
The ordination is overlain by vectors proportional to the strength of their correlation with ordination axes. Spearman r values for each variable are provided in Table 2. Convex hulls surround plots in each distance class. All two letter abbreviations are elements, and those followed by “_2001” are modeled values from 2001 sampling [18]. Mean elemental values were mg/kg in Hylocomium splendens tissue, dry weight, except % Total S and % Total N. Other abbreviations are: Total_S (Total sulfur), Hylspl_Cov (H. splendens cover), LogDist_Rd (log10 distance to the road), Total_N (Total nitrogen), Log_LSR (log10 lichen species richness), LSR (lichen species richness), P (phosphorus), Dist_Rd (Distance to the road), P (phosphorus).
Table 7.
Indicator species analysis of bryophyte taxon groups by distance class groups from the DMTS haul road, CAKR.
Only results with p values < 0.05 are shown below. Hylocomium splendens does not appear as all indicator values for this group had p values > 0.05. Tests were run for each distance class individually and for 10–300 m vs. 1000–4000 m.