Final Report: Understanding Local Resistance and Resilience to Future Habitat Change in the Sagebrush Ecosystem
Dates
Publication Date
2022-10-17
Citation
Daniel Manier, and Michael S O'Donnell, 2022-10-17, Final Report: Understanding Local Resistance and Resilience to Future Habitat Change in the Sagebrush Ecosystem: .
Summary
The sagebrush ecosystem is home to diverse wildlife, including charismatic species such as pronghorn, pygmy rabbits, mule deer and Greater Sage-Grouse. Historic and contemporary land-uses, large wildfires, non-native (introduced) plant invasions, climate cycles with droughts, and long-term climate trends characterize the list of widespread threats to this heavily used landscape. Semi-arid habitats, such as sagebrush ecosystems, present challenges for management due to natural limitations and variability in growing conditions across the landscape and over time. Differences in environmental conditions lead to differences in plant composition, fuel accumulation, resilience to stress and disturbance and restoration/management outcomes. [...]
Summary
The sagebrush ecosystem is home to diverse wildlife, including charismatic species such as pronghorn, pygmy rabbits, mule deer and Greater Sage-Grouse. Historic and contemporary land-uses, large wildfires, non-native (introduced) plant invasions, climate cycles with droughts, and long-term climate trends characterize the list of widespread threats to this heavily used landscape. Semi-arid habitats, such as sagebrush ecosystems, present challenges for management due to natural limitations and variability in growing conditions across the landscape and over time. Differences in environmental conditions lead to differences in plant composition, fuel accumulation, resilience to stress and disturbance and restoration/management outcomes. Much variability is created by the combination of soil and climate conditions that create a water availability gradient. Therefore, climate-soil-plant relations describe a fundamental ecosystem function with direct implications for management. Until now, lack of accurate representation of the spatial and temporal heterogeneity in soil moisture and temperature have restricted use of soil-climate in ecological applications.
We created a simulation model that accounts for soil water content over the course of a year using precipitation, temperature, soil water capacity, evapotranspiration, and related environmental characteristics (such as topography) across large landscapes. We modeled soil-climate using averaged climate conditions (30-years) across 313 million hectares (774 million acres) of the western U.S., encompassing most of the sagebrush biome (approximately 17 million hectares were excluded along the southern extent, but sagebrush cover is very low there). The model produced spatially independent cell-by-cell soil-climate classification and estimates of soil moisture across the entire region. Models were tested using climate station data, qualitative comparison with soil data, and correlation with ecological patterns using shrub and annual grass cover, exposed soil, and fire frequency. Analyses indicated strong connections between our results and landscape patterns: 66% of variation (deviance explained) in exposed bare ground (inverse of plant cover) was explained by spring soil moisture alone, and 51% of the variability in sagebrush cover was explained by combination of spring and winter soil moisture. Importantly, soil moisture combined with burn frequency explained 69% of the deviance in annual herbaceous grasses across the region (this is very strong). These results improve understanding of ecosystem patterns (demonstrated by plant cover here) and management risks (such as, fire and invasion) and provide useful data for management and research applications.
