Persistent land degradation is one of the most pressing challenges facing land managers in the southwestern US and on drylands globally. Areas of persistent ecosystem degradation occur on public lands throughout the southwestern US due to drying climate and land use. However, degraded areas often occur in close proximity to relatively intact ecosystems, where differences in climate and land use are minor compared to the contrast in ecosystem condition. Soil-geomorphic properties that mediate plant responses to climate may drive landscape heterogeneity in ecological conditions. Soil-geomorphic properties affect infiltration, soil water storage, evaporation, and run-off, which impact water availability for plants. These characteristics are especially influential in semi-arid environments, where water is a limiting resource for plant establishment, growth, and persistence. Understanding conditions that influence plant community resilience can guide land use policies to limit use of vulnerable areas during drought.
Results/Conclusions
In this study, we assess how soil-geomorphic properties mediate climate conditions to influence plant community composition and trends in productivity in three national parks on the Colorado Plateau. Landsat time-series analysis and hierarchical clustering of species cover data identified strong associations between soil-geomorphic characteristics and plant community types and behavior. We find that sandy alluvium and saline soil geomorphic units in valley bottoms were more predisposed to non-native annual species invasion. We also find that plant species composition varies with soil-geomorphic and climate properties that drive water availability, including soil depth, salinity, landform, and maximum annual temperature. Our study provides new information to assist land managers in maintaining and restoring plant communities affected by past and present stressors.