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Big Sagebrush Response to Wildfire and Invasive Grasses in the 21st Century

Big Sagebrush Plant Community Response to Wildfire and Invasive Annual Grasses in the 21st Century
Principal Investigator
Kyle Palmquist


Start Date
End Date
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Big sagebrush plant communities are important and widespread in western North America and are crucial for meeting long-term conservation goals for greater sage-grouse and other wildlife of conservation concern. Yet wildfire is increasing in the West, turning biodiverse, shrub-based ecosystems dominated by sagebrush into grasslands containing invasive species such as cheatgrass and less overall plant and animal diversity. These transformations negatively impact people and ecosystems by reducing habitat quality for wildlife and the aesthetic value of the landscape. Understanding how sagebrush communities are already responding and will continue to respond to changes in wildfire, invasive species, and climate is a priority for managers [...]

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Wildfire is increasing in the western US, with negative implications for big sagebrush rangelands and the numerous species that depend on them. More frequent fire in these systems can provide opportunities for invasive grass species to colonize and further promote fire, resulting in transitions from native shrublands to non-native grasslands. These transformations and increases in wildfire negatively impact people and ecosystems by reducing habitat quality and aesthetic value, and altering ecosystem services. We currently know very little about how invasive grasses and fire will affect big sagebrush rangelands in the future and whether all big sagebrush systems in the western US will be negatively affected. Our overall objective is to address this knowledge gap and provide expectations for the vulnerability of big sagebrush plant communities to transformation in response to future climate, fire, and invasive grasses to guide conservation prioritization and planning efforts across the big sagebrush region. This work will provide resource and land managers with maps of what future plant communities will look like and focus on aspects of the plant community that are most relevant for range-wide management priorities. We will identify areas that are expected to be most vulnerable to invasive species in the future and identify areas that we expect will remain resistant to invasive species, so managers can concentrate limited resources in areas that will be the least vulnerable in the future.

Project Extension

typeTechnical Summary
valueEcosystems dominated by big sagebrush (Artemisia tridentata) once covered >68 million ha of western North America. However, the combination of invasive annual grasses and enhanced wildfire frequency are rapidly converting many of these shrub-dominated ecosystems into annual grasslands, with reduced plant diversity and dramatically diminished habitat value. Although these conversions are widespread, they are not geographically ubiquitous across the big sagebrush biome, which implies variation in long-term vulnerability that can be utilized by resource managers to efficiently target conservation efforts. Furthermore, these conversions are not consistent through time, underscoring the key role of climate variability in mediating wildfire-invasive interactions. We propose to utilize STEPWAT2, a dryland ecological simulation model, to assess long-term, range-wide vulnerability of big sagebrush ecosystems to climate variability, grazing pressure, and wildfire-driven conversion to invasive annual grasslands. STEPWAT2 is a plant community model that integrates detailed ecohydrological information with plant demographics to assess temporal dynamics of plant species and functional groups in response to climate and disturbance. Working with US Fish & Wildlife Service partners, our collaborative team from the USGS and the University of Wyoming have recently updated and enhanced STEPWAT2 and this project will leverage that progress to assess the individual and combined impact of climate variability, wildfire, and invasive annual grasses on big sagebrush plant communities in 91 sites across their distribution for the remainder of the 21st century. We will focus on areas with high breeding population densities of greater sage-grouse. These results will provide detailed site-specific information as well as synthetic, range-wide perspectives on the vulnerability of big sagebrush ecosystems that are directly linked to several knowledge gaps identified in the Actionable Science Plan and the 2018-2023 Northwest CSC Science Agenda. In addition, we expect this funding will result in 3 peer-reviewed publications. We will work with managers to create geographic maps of aspects of future plant communities for different climate-disturbance scenarios that are most relevant for range-wide management priorities and create a web interface to view and interact with the data.
projectStatusIn Progress

Budget Extension

typeAward Type
valueCooperative Agreement
typeAward Number

Sagebrush, WY, USGS - Credit
Sagebrush, WY, USGS - Credit


Spatial Services

ScienceBase WMS


  • National and Regional Climate Adaptation Science Centers
  • North Central CASC
  • Northwest CASC
  • Southwest CASC



Additional Information


Type Scheme Key
RegistrationUUID NCCWSC 51b36977-160f-4407-a3ca-4e7e6c8bc608
StampID NCCWSC NC18-PK1333

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