Ecohydrological responses to climate change will exhibit spatial variability in response to gradients of climate and topography, and understanding the spatial pattern of ecological impacts is critical from a land management perspective. To quantify the impacts of altered climate on spatial variability in future ecohydrology across big sagebrush ecosystems, we asked: How will climate change impacts on ecohydrology differ in magnitude and variability across sites for big sagebrush ecosystem types (SB-Shrubland, SB-Steppe, SB-Montane) and across geographic space? We summarized changes across geographic space using the seven Sage-grouse Management Zones in the western US. We explored these potential changes for mid-century (2030-2060) using a process-based water balance model (SOILWAT) for 898 big sagebrush sites using site-specific climate information, vegetation parameters, and soil properties for multiple soil layers. We focus on summarizing changes in available soil water (ASW) and dry days from current conditions to mid-century, as these ecohydrological variables are most relevant to land managers and this work is designed to inform land management decisions about where to geographically concentrate climate change mitigation and adaptation resources in the coming decades.
Results/Conclusions
Our results suggest that during spring, soils will be wetter in the future across the big sagebrush region, while soils will be drier in the summer. The magnitude of those predictions differed across the western US, with larger increases in spring ASW expected for high-elevation SB-Montane sites (+4mm) and the eastern and central big sagebrush region (+1-7mm). The largest decreases in summer ASW were projected for warm, dry, mid-elevation SB-Montane sites in the central and west-central portion of our study area (-2mm). Similar to our results for summer ASW, the number of dry days was projected to increase rangewide, suggesting drier summer conditions in the future, but particularly for SB-Montane and SB-Steppe sites in the eastern and northern regions. Collectively, these results suggest that most sites will be drier in the future during the summer, but changes were especially large for mid- to high-elevation sites in the northern half of our study area. Although drier summer conditions are expected rangewide, this may result in increased habitat suitability for big sagebrush and greater sage-grouse habitat in high elevation SB-Montane sites, but decreased suitability for the dry ecosystem types, with important implications for where land managers should prioritize resources in the future.