DOI: 10.5061/dryad.h18931zpb
title: New indicators of ecological resilience and invasion resistance to support prioritization and management in the sagebrush biome, United States

description: Ecosystem transformations to altered or novel ecological states are
 accelerating across the globe. Indicators of ecological resilience to
 disturbance and resistance to invasion can aid in assessing risks and
 prioritizing areas for conservation and restoration. The sagebrush biome
 encompasses parts of 11 western states and is experiencing rapid
 transformations due to human population growth, invasive species, altered
 disturbance regimes, and climate change. We built on prior use of static
 soil moisture and temperature regimes to develop new, ecologically
 relevant and climate-responsive indicators of both resilience and
 resistance. Our new indicators were based on climate and soil water
 availability variables derived from process-based ecohydrological models
 that allow predictions of future conditions. We asked: (1) Which variables
 best indicate resilience and resistance? (2) What are the relationships
 among the indicator variables and resilience and resistance categories?
 (3) How do patterns of resilience and resistance vary across the area? We
 assembled a large database (n = 24,045) of vegetation sample plots from
 regional monitoring programs and derived multiple climate and soil water
 availability variables for each plot from ecohydrological simulations. We
 used USDA Natural Resources Conservation Service National Soils Survey
 Information, Ecological Site Descriptions, and expert knowledge to develop
 and assign ecological types and resilience and resistance categories to
 each plot. We used random forest models to derive a set of 19 climate and
 water availability variables that best predicted resilience and resistance
 categories. Our models had relatively high multiclass accuracy (80% for
 resilience; 75% for resistance). Top indicator variables for both
 resilience and resistance included mean temperature, coldest month
 temperature, climatic water deficit, and summer and driest month
 precipitation. Variable relationships and patterns differed among
 ecoregions but reflected environmental gradients; low resilience and
 resistance were indicated by warm and dry conditions with high climatic
 water deficits, and moderately high to high resilience and resistance were
 characterized by cooler and moister conditions with low climatic water
 deficits. The new, ecologically-relevant indicators provide information on
 the vulnerability of resources and likely success of management actions
 and can be used to develop new approaches and tools for prioritizing areas
 for conservation and restoration actions.
description: We assembled a large database (n = 24,045) of vegetation sample
 plots from regional monitoring programs and derived multiple climate and
 soil water availability variables for each plot from ecohydrological
 simulations. We used USDA Natural Resources Conservation Service National
 Soils Survey Information, Ecological Site Descriptions, and expert
 knowledge to develop and assign ecological types and resilience and
 resistance categories to each plot. We used random forest models to derive
 a set of 19 climate and water availability variables that best predicted
 resilience and resistance categories. 
description: All code scripts are RStudio notebooks, which are RMarkDown files
 additionally formatted to render to HTML. Input files can be .csv files
 (plain text, common-separated files) or RDS files (R data
 objects).