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Visualize spatial data from this project: Future SEI
See photos from the field showcasing landscapes representing a range of Sagebrush Ecological Integrity (as mapped by Doherty et al., 2022)
Project Description
Background: Sagebrush ecosystems are a major component of landscapes in the Western U.S. Climate change has the potential to substantially alter big sagebrush dominated plant communities as their structure and function are closely tied to soil moisture and temperature. Ecosystem services provided by the sagebrush biome are already threatened by multiple simultaneous processes, including invasive annual plants, altered fire regimes, conifer expansion, climate change, and human land use. Defending and growing core sagebrush habitats in the face of these threats requires information that enables spatially targeted management. More information about some of this work can be found on the Sagebrush Conservation Gateway
Objectives:
Broadly, our goal is to understand the climatic, and edaphic controls over sagebrush ecosystems and forecasting how sagebrush ecosystems may change in the future. We strive to understand impacts of feedbacks between wildfire, and invasive species as well as a broad array of climate projections to evaluate uncertainty due to climate variability.
Specifically, we are working on addressing the following questions:
How do climate and fine fuels drive long term wildfire probability in sagebrush ecosystems and how might fire regimes change in the future?
How will biome-wide patterns of sagebrush core habitat areas be altered in coming decades by the combination of climate change and feedbacks between vegetation and wildfires?
How robust are projected 21st century changes in sagebrush ecological integrity to uncertainty in future climate conditions represented by climate models and representative concentration pathways?
What plant functional types are driving projected shifts in sagebrush ecological integrity?
Approach: We use the SOILWAT2 ecosystem water balance model to simulate sagebrush plant community responses to future climate, wildfire, grazing, and invasion by annual grasses. To improve our representation of wildfire we created a statistical model using historical wildfire occurrence, gridded climate data, and remotely sensed herbaceous biomass data which we then incorporated into SOILWAT2 (wildfire dynamics are relevant to all questions). To create projections of sagebrush core habitats under future conditions (questions 2-3), we combine simulated sagebrush community responses with remote sensing based estimates of sagebrush ecosystem integrity that have been developed as part of the ongoing Sagebrush Conservation Design effort (Doherty et al., 2022).
Outcomes
Question 1: How do climate and fine fuels drive long term wildfire probability in sagebrush ecosystems and how might fire regimes change in the future? We fit a climate-sensitive statistical model to observed fire-occurrence, climate (temperature, annual precipitation, and the proportion of precipitation received in June-August), and fine fuels (remote sensing based estimates of aboveground biomass of annual and perennial herbaceous plants). This relatively simple model (which is a closed form equation) predicts annual wildfire probability and has been incorporated into SOILWAT2. In ongoing work we are using SOILWAT2 to explore wildfire-vegetation-climate feedbacks. See Holdrege et al. (2024b) for more details.
This figure shows relationship between wildfire probability, climate and fine fuels across the sagebrush region. Panels show mean observed (black circles) and predicted (blue triangles) annual wildfire probability for each percentile of a) mean temperature, b) annual precipitation, c) proportion summer precipitation (PSP), d) aboveground biomass of annual forbs and grasses, and e) aboveground biomass of perennial forbs and grasses (values of all predictor variables were calculated as 3-year running averages). Corresponding fire return intervals (FRI) are shown on the secondary (right) y-axis. Data were binned by percentile (i.e., 100 bins) of a given predictor variable, and the x-axis (panels a-e) shows the mean value of each percentile of that variable. Each point represents the mean of ~250,000 observations (i.e., 1% of the entire dataset used). In panel f) mean observed and predicted annual wildfire probability values shown in panels a-e are plotted against each other (1:1 line shown for reference). See Holdrege et al. (2024b) for more details.
Question 2: How will biome-wide patterns of sagebrush core habitat areas be altered in coming decades by the combination of climate change and feedbacks between vegetation and wildfires? Here we show the potential changes core sagebrush areas (CSA), growth opportunity areas (GOA) and other rangeland areas (ORA). The map shows the median change in this sagebrush ecological integrity classification from current (2017-2021) to future (RCP 4.5, 2071-2100) climate conditions. Results are based on simulations that incorporated vegetation-wildfire feedbacks. Reds denote areas where we projected losses of CSA or GOA. See Holdrege et al. (2024a) for more details.
Question 3: How robust are projected 21st century changes in sagebrush ecological integrity to uncertainty in future climate conditions represented by climate models and representative concentration pathways? Total area in the nine possible changes of sagebrush ecological integrity (SEI) classification for two emissions scenarios (RCP4.5 and RCP8.5) and two time periods (2031-2060, 2071-2100). The bars with no hash marks (RCP4.5, 2071-2100) correspond to the areas shown in the map above. Bars show the area based on calculating the median future SEI across 13 GCMs at each grid-cell. Error bars show the range in area based on using the 2nd lowest and 2nd highest SEI values across GCMs at each grid-cell. Note that while 9 changes in sagebrush ecological integrity classification are possible, the ‘ORA becomes CSA’ (black) and ‘CSA becomes ORA’ (dark red) categories do not appear on the map (because they represent approximately zero area). See Holdrege et al. (2024a) for more details.
a) Agreement among climate models for change in sagebrush ecological integrity classification (under RCP4.5 2071-2100) for areas that are currently Core Sagebrush Areas (CSA) or Growth Opportunity Areas (GOA). b) Area of the categories shown in panel a. ‘Non-robust agreement’ indicates agreement among 7-11 models out of 13 (light colors, not a robust signal), and ‘robust agreement’ means agreement among 12-13 models (dark colors, a robust signal). Loss of CSA means future classification is GOA or ORA. Loss of GOA means future classification is ORA. See Holdrege et al. (2024a) for more details.
Question 4: What plant functional types are driving projected shifts in sagebrush ecological integrity (SEI)? a) Relative contribution of changing abundance of sagebrush (red), perennial grasses (green), and annual grasses (blue) to changes in SEI, for RCP4.5 2071-2100. b) Region-wide area most impacted by changes in each component for each SEI class change category. The primary driver of change was defined as the plant functional type that had the greatest impact on the change in SEI in a given grid-cell. Areas where no single plant functional type was the primary driver of change are shown in gray. Abbreviations: CSA, Core Sagebrush Area; GOA, Growth Opportunity Area; ORA, Other Rangeland Area. See Holdrege et al. (2024a) for more details.
Products
Products
Interactive web-app: projected SEI layers
Publications:
Doherty, K.E., J. Maestas, T. Remington, D.E. Naugle, C. Boyd, L. Wiechman, G. Bedrosian, M. Cahill, P. Coates, M. Crist, M.C. Holdrege, A.V. Kumar, T. Mozelewski, R.C. O'Connor, E.M. Olimpi, A. Olsen, B.G. Prochazka, J.R. Reinhardt, J.T. Smith, W.D. Sparklin, D.M. Theobald, K. Wollstein, 2024, State of the Sagebrush: Implementing the Sagebrush Conservation Design to Save a Biome, Rangeland Ecology & Management, 97:1-11. https://doi.org/10.1016/j.rama.2024.08.017, Webpage describing this work
Holdrege, M.C., K.A. Palmquist, D.R. Schlaepfer, W.K. Lauenroth, C.S. Boyd, M.K. Creutzburg, M.R. Crist, K.E. Doherty, T.E. Remington, J.C. Tull, L.A. Wiechman, J.B. Bradford, 2024a. Climate Change Amplifies Ongoing Declines in Sagebrush Ecological Integrity. Rangeland Ecology & Management, 97:25–40 https://doi.org/10.1016/j.rama.2024.08.003, Webpage describing this work, In the news
Holdrege M.C, D.R. Schlaepfer, K.A. Palmquist, M. Crist, K.E. Doherty, W.K. Lauenroth, T.E. Remington, K. Riley, K.C. Short, J.C. Tull, L.A. Wiechman, and J.B. Bradford, 2024b, Wildfire probability estimated from recent climate and fine fuels across the big sagebrush region. Fire Ecology, 20 (22) https://doi.org/10.1186/s42408-024-00252-4
Boyd, C. S., M. K. Creutzburg, A. V. Kumar, J. T. Smith, K. E. Doherty, B. A. Mealor, J. B. Bradford, M. Cahill, S. M. Copeland, C. A. Duquette, L. Garner, M. C. Holdrege, B. Sparklin, and T. B. Cross. 2024. A Strategic and Science-Based Framework for Management of Invasive Annual Grasses in the Sagebrush Biome. Rangeland Ecology & Management 97:61-72. https://doi.org/10.1016/j.rama.2024.08.019, Webpage describing this work
Doherty, K., Theobald, D.M., Bradford, J.B., Wiechman, L.A., Bedrosian, G., Boyd, C.S., Cahill, M., Coates, P.S., Creutzburg, M.K., Crist, M.R., Finn, S.P., Kumar, A.V., Littlefield, C.E., Maestas, J.D., Prentice, K.L., Prochazka, B.G., Remington, T.E., Sparklin, W.D., Tull, J.C., Wurtzebach, Z., and Zeller, K.A., 2022, A sagebrush conservation design to proactively restore America’s sagebrush biome: U.S. Geological Survey Open-File Report 2022–1081, 38 p., https://doi.org/10.3133/ofr20221081.
Data releases:
Holdrege, M.C., Schlaepfer, D.R., Palmquist, K.A., Theobald, D.M., and Bradford, J.B., 2024, Current and projected sagebrush ecological integrity across the Western U.S., 2017-2100: U.S. Geological Survey data release, https://doi.org/10.5066/P13RXYZJ
Holdrege, M.C., Schlaepfer, D.R., and Bradford, J.B., 2024, Observed wildfire frequency, modeled wildfire probability, climate, and fine fuels across the big sagebrush region in the western United States: U.S. Geological Survey data release, https://doi.org/10.5066/P9EFC6YC
Doherty, K., Theobald, D.M., Holdrege, M.C., Wiechman, L.A., and Bradford, J.B., 2022, Biome-wide sagebrush core habitat and growth areas estimated from a threat-based conservation design: U.S. Geological Survey data release, https://doi.org/10.5066/P94Y5CDV
Presentations:
Holdrege, M. C, Schlaepfer, D. A, and Bradford, J. B. Identifying and assessing sources of uncertainty in climate change effects on big sagebrush plant communities. Society for Range Management 2025 Annual Meeting. Spokane, WA. February 11, 2025.
Holdrege, M. C, Schlaepfer, D. A, Palmquist, K. A., Lauenroth, W. K., Boyd, C. S., Creutzburg, M. K., Crist,, M. R., Doherty, K. E., Remington, T. E., Tull, J. C., Wiechman, L. A., and Bradford, J. B. Climate change amplifies losses of sagebrush ecological integrity. U.S Fish and Wildlife Service Sagebrush climate training. Boise, ID. May 21, 2024. Link to slides, Link to recording
Holdrege, M. C, and Bradford, J. B. Climate change impacts on sagebrush ecosystems. U.S Fish and Wildlife Service virtual classroom. March 20, 2024. Link to recording
Holdrege, M. C, Schlaepfer, D. A, Palmquist, K. A., Lauenroth, W. K., Boyd, C. S., Creutzburg, M. K., Crist, M. R., Doherty, K. E., Remington, T. E., Tull, J. C., Wiechman, L. A., Bradford, J. B. Assessing the future of core sagebrush areas: impacts of climate & climate uncertainty, wildfire and invasive species. USGS Sagebrush and Fire Research Information Transfer Webinar. February 29, 2024.
Holdrege, M. C, Schlaepfer, D. A, Palmquist, K. A., Lauenroth, W. K., Boyd, C. S., Creutzburg, M. K., Crist,, M. R., Doherty, K. E., Remington, T. E., Tull, J. C., Wiechman, L. A., and Bradford, J. B. Climate change promotes declines in sagebrush habitat quality. Society for Range Management 2024 Annual Meeting. Sparks, NV. January 31, 2024.
Holdrege, M.C., Lauenroth, W.K., Doherty, K.E., Palmquist, K.A., Schlaepfer D.R., and Bradford J.B. How will climate change alter the extent of core sagebrush areas? Ecological Society of America 2023 Annual Meeting. Portland, OR. August 9, 2023.
Holdrege, M.C., K.A. Palmquist, M. England, R.R. Renne, D.R. Schlaepfer, K.E. Doherty, T.E. Remington, W.K. Lauenroth, and J.B. Bradford. Grazing management may moderate the effects of climate change on big sagebrush plant communities. 16th Biennial Conference of Science & Management for the Colorado Plateau & Southwest Region. Flagstaff, AZ. September 12, 2022.
Collaborators
Chad Boyd - U.S. Department of Agriculture, Agricultural Research Service
Megan Creutzburg - Oregon State University, Institute for Natural Resources
Michele Crist - Bureau of Land Management, Fire Planning and Fuels Management Division
Kevin Doherty, John Tull - U.S. Fish and Wildlife Service, Science Applications Program
William Lauenroth - Yale University, School of the Environment,
Kyle Palmquist - Marshall University, Department of Biological Sciences
Thomas Remington - Western Association of Fish and Wildlife Agencies
Karin Riley, Karen Short - U.S. Forest Service, Rocky Mountain Research Station
Lief Wiechman - U.S. Geological Survey, Ecosystems Mission Area
Support
U.S. Fish and Wildlife Service, Bureau of Land Management, USGS Ecosystems Mission Area, and the USGS Climate Adaptation Science Centers
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