The southwestern region of the United States (US) is one of the hottest and driest areas of North America and climate change is likely to exacerbate these conditions. This region is home to a large number of threatened or endangered species, including many endemic plants. Plants inhabiting these desert environments may already exist close to their physiological limits for temperature and water stress, and projected higher temperatures and decreased precipitation could result in altered distributions or localized extirpations. Wildlife species (migratory birds, resident rodents, pollinating insects, etc.) depend on specific plants in these sparsely vegetated areas, thus desert ecosystem resilience could be reduced with loss of threatened plant species. Desert ecosystems also provide important benefits to human communities, such as regulation of water flow and opportunities for recreation and ranching, all of which may be impacted by shifts in vegetation distribution or community composition. Species response to altered temperature and precipitation regimes is lacking for most desert plants however, and climate change impacts on threatened species remains largely unknown. Here we used vulnerability assessments and species distribution models (SDMs) to determine threatened plant species most impacted by climate change, and identify areas for future conservation actions in the southwestern US.
Results/Conclusions
We evaluated the vulnerability of each species under future climate scenarios and scores were calculated using metrics such as exposure, sensitivity, niche breadth, and dispersal capability. Threatened plant species identified as highly or extremely vulnerable (approximately half) were selected for SDMs. Vulnerability assessments identified several non-climatic variables as important, such as soil type, and these were incorporated into SDMs when data were available. Results indicated that the climatic niche of most threatened plant species was governed primarily by precipitation variables, and substantial loss in habitat was predicted for the majority of plant species. Areas of potential future suitable habitat were identified based upon SDM results and several criteria were used to rank proposed conservation areas. Our study demonstrates the utility of a spatially explicit index which can aid in conservation planning under changing climatic regimes. This information related to climate change vulnerabilities and future distribution can be used by natural resources managers to better inform ecological decisions about threatened or endangered plants in the southwest.