Future dryland resistance and resilience
Project description
Background: Drylands are being transformed by the combination of climate change, altered disturbance regimes, biological invasions and land use. In addition, drought and disturbances may combine in coming decades to accelerate large-scale dryland transformations. As a result, resource managers need reliable understanding of geographic patterns in ecosystem vulnerability. But, recent work has identified several important limitations to existing ecological assessments of climate change vulnerability, ecological resilience and resistance to invasive annuals. Therefore, this project is working to overcome those limitations by identifying new, ecologically-relevant indicators of ecological R&R in drylands and mapping those indicators under historical and future climate conditions.
Objectives: This project provided new metrics of ecological resilience and resistance to invasive plants. We integrated a proven ecosystem water balance model with widespread observational data about dryland plant community responses to disturbances to develop and deliver improved metrics of R&R. Specifically, we addressed the following objectives:
1. Develop R&R metrics from ecosystem water balance simulations.
2. Assess current spatial patterns in the R&R indicators developed in objective 1.
3. Quantify long-term trajectories of R&R indicators under future climate.
Approach: For objective 1, we used the SOILWAT2 ecosystem water balance model to simulate patterns of ecological drought as indicators of ecological resilience to wildfire and resistance to invasive plants. These results provided detailed water balance modeling from which we can identify the specific moisture and temperature metrics that explain R&R in drylands. For objective 2, we expanded the water balance simulations estimate the distribution of new R&R indicators across the extent of the sagebrush region. For objective 3, we utilized projections from global climate models as input to our water balance model, quantifying how changes in climate will alter both the indicators and R&R categories. We explicitly quantified how variation among climate projections impacts uncertainty in future R&R changes.
Outcomes
Objective 1 - Develop R&R metrics from ecosystem water balance simulations
We developed a new suite of climate and drought metrics of ecological resilience to wildfire and resistance to invasive plants. These metrics are designed to represent important conditions for dryland plant communities and vegetation dynamics (see table on right). The manuscript describing these results is published in Ecohydrology (Chenoweth et al. 2023).
Objective 2 – Assess current spatial patterns in the R&R indicators
We integrated our suites of climate and ecological drought indicators (objective 1) with field data about plant community composition and expert knowledge to generate a new predictive algorithm for estimating ecological resistance and resilience. We then applied that new algorithm to estimate R&R in sagebrush and dry woodland ecoregions across the western U.S. and have published those results (Chambers et al. 2023.) Figures below (from Chambers et al 2023): Left: proportion of total area in different resilience and resistance categories in each of the ecoregions. Portions of ecoregions that lie outside of the sagebrush biome are unclassified (“NA”). NBR = Northern Basin and Range; SRP = Snake River Plain; CBR = Central Basin and Range; CP = Colorado Plateau; WB = Wyoming Basin; MR = Middle Rockies; NWGP = Northwestern Great Plains. Right: maps of predicted (a) resilience and (b) resistance for the study area with Level III EPA ecoregions and states delineated (US EPA 2022). Areas that do not support the focal ecosystems are shown in light yellow (“NA”).
Objective 3: Quantify future trajectories of R&R indicators under climate change.
We utilized projections from global climate models as input to our water balance model, quantifying how changes in climate will alter the distribution of both the indicators and R&R categories. We found that in general, climate change is expected to decrease both resistance and resilience across most of the drylands. Maps at right show a continuous index of predicted resilience (A, C) and resistance (B, D) for the study region under ambient conditions (1980-2020; A, B) and maps of median change in the predicted continuous index (C, D) between simulations under future projected (RCP 4.5 2064-2099) and historical (1950-2005) climate condition. Cross-hatching marks areas where <= 18 out of 20 of climate projections are consistent in the direction of change. Insets show area-weighted density distributions (separated by robust (orange) and other (blue) areas in C, D). Level III EPA ecoregions (US EPA, 2022) and administrative boundaries (states, provinces) are delineated. Areas that are not big sagebrush or woodland ecosystems are shown in gray.
Other outcomes
Publications
Chenoweth, D. A., D. R. Schlaepfer, J. C. Chambers, J. L. Brown, A. K. Urza, B. Hanberry, D. Board, M. Crist, and J. B. Bradford. 2023. Ecologically relevant moisture and temperature metrics for assessing dryland ecosystem dynamics. Ecohydrology:e2509. https://doi.org/10.1002/eco.2509
Chambers, J. C., J. L. Brown, J. B. Bradford, D. I. Board, S. B. Campbell, K. J. Clause, B. Hanberry, D. R. Schlaepfer, and A. K. Urza. 2023. New indicators of ecological resilience and invasion resistance to support prioritization and management in the sagebrush biome, United States. Frontiers in Ecology and Evolution 10.
Schlaepfer, D.R., Chambers, J.C, Brown, J.L., Board, D.I., Campbell, S.B., Clause, K.J., Hanberry, B., Urza, A K., and Bradford, J.B. In Preparation. Rethinking indicators of dryland resistance and resilience for the 21st century.
Data releases:
Schlaepfer, D. R., Andrews, C. M., & Bradford, J. B. (2022). Historical and future ecological drought conditions for rangelands of the western U.S. U.S. Geological Survey Data Release. https://doi.org/10.5066/P97S8RAC
Schlaepfer, D.S. and Bradford, J.B. In Preparation. Projected indicators of dryland resistance and resilience for rangelands in the Sagebrush Biome for the 21st century. U.S. Geological Survey Data Release.
Schlaepfer, D.S. and Bradford, J.B. In Preparation. Ecologically relevant annual (1980-2021) moisture and temperature metrics for rangelands in the Sagebrush Biome. U.S. Geological Survey Data Release.
Presentations:
Bradford, J.B. & Schlaepfer, D.S. 2020. Climate change impacts on dryland resistance-resilience & sagebrush plant communities. USGS Sagebrush and wildfire information transfer workshop. December 9, 2020. Online: 101 attendees.
Bradford, J.B. 2021. Climate change impacts on soil moisture and implications for plant regeneration in drylands. University of Arizona Rangeland Resilience Seeding Workshop. October 5, 2021. Virtual. ~30 attendees.
Bradford, J.B. et al. 2022.New resilience and resistance metrics for assessing climate change impacts in drylands. USDA Forest Service and JFSP planning meeting. February 8, 2022. Online.
Bradford, J.B. et al. 2022. New metrics for quantifying ecological drought to inform resilience and resistant in drylands. Society for Rangeland Management 2022 Annual Meeting. Feb 9, 2022. Online.
Bradford, J.B. 2022. Climate change, ecological drought & vegetation challenges in western drylands. High Altitude Revegetation Conference. April 13, 2022. Fort Collins, CO. Keynote Address.
Bradford, J.B., Crist, M. Chenoweth, D.A., Schlaepfer, D.R., Chambers, J.C., Urza, A., Hanberry, B, Brown, J., Board, D.I. 2022. Ecological drought metrics to understand dryland ecosystem dynamics. Ecological Society of America Annual Meeting. Montreal, Canada, August 2022.
Bradford, J.B., D.A. Chenoweth, D.R. Schlaepfer, J.C. Chambers, J.L. Brown, J.L., A.K. Urza, B. Hanberry, D. Board, and M. Crist. 2022. Ecological drought metrics to understand dryland ecosystem dynamics. Biennial Conference of Science & Management for the Colorado Plateau & Southwest Region, Flagstaff, AZ.
Schlaepfer, D.R., J.C. Chambers, J.L. Brown, D.I. Board, S.B. Campbell, K.J. Clause, B. Hanberry, A.K. Urza, M. Crist, and J.B. Bradford. 2022. Rethinking indicators of dryland resistance and resilience for the 21st century. Biennial Conference of Science & Management for the Colorado Plateau & Southwest Region, Flagstaff, AZ.
Bradford et al. 2022. Understanding climate change & ecological drought impacts on dryland vegetation & plant communities: how we use AIM data. Nov 10, 2022.
Collaborators
Jeanne Chambers, Alexandra Urza, Brice Hanberry, Jessi Brown- USDA Forest Service, Rocky Mountain Research Station.
Michele Crist: Bureau of Land Management - Fire Planning and Fuels Management Division
Support
Bureau of Land Management and USGS Ecosystems Mission Area Land Management Research Program