Southwest Biological Science Center
Big Sagebrush Ecosystem Response to Climate & Disturbance
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Big sagebrush ecosystems are a major component of landscapes in the western U.S. and provide vital habitat to a wide array of wildlife species. However, big sagebrush ecosystems have been dramatically impacted by disturbances in the past several decades. This collaborative research between USGS and the University of Wyoming focuses on understanding how climatic and soil conditions influence big sagebrush ecosystems and forecasting how sagebrush ecosystems may change in the future.
Background & Importance
Big sagebrush ecosystems are a major component of the western United States and are identified as a focal ecosystem type for meeting greater sage-grouse conservation targets. However, the future of sagebrush ecosystems is highly uncertain. Climate and disturbance are key factors that determine the distribution of plants and plant communities. In sagebrush ecosystems of the western US, both are changing at unprecedented rates. Temperatures have risen over the past several decades and this change is predicted to accelerate over the first half of the 21st century. Rising temperatures will result in increased potential evapotranspiration and declines in snowpack, with the overall effect of increasing aridity in much of the western U.S.
More than a dozen sage grouse in a shrubland/grassland in southwest Wyoming. (Credit: John Bradford, USGS. Public domain.)
Sagebrush ecosystems provide crucial wildlife habitat and numerous ecosystem services. In particular, effective long-term sage grouse conservation relies on understanding the structural complexity, plant species composition, and geographic distribution of sagebrush ecosystems in the future. Products from this research are designed to help address many of those knowledge gaps. The overall goal of this work is to understand how changes in climate and associated ecohydrological conditions will impact sagebrush ecosystems over the next century.
General Methods
Strategies for effectively generating relevant regional-scale resource management are extremely limited. In conjunction with collaborators at the University of Wyoming, SBSC scientists are working to represent regional-scale variability and provide range-wide understanding about how sagebrush is influenced by climate and soils. Developing such widely applicable insights requires integrating ecological models that can represent edaphic and climatic variability and spatial analysis tools that describe geographic patterns. We utilize ecological simulation models and geostatistical analysis of sagebrush ecohydrological niche to generate useful forecasts of how sagebrush ecosystems may change in the future. This work includes several closely-related projects supported by funding from the U.S. Fish and Wildlife Service, the North Central Climate Science Center and the DOI on the Landscape Program.
Important Results
Big sagebrush depends on winter precipitation: Despite its extremely wide geographic distribution, our work identified that sagebrush exists only in places where soil moisture is reliably recharged during the cool season when evapotranspiration is lower than precipitation. (See Schlapefer et al 2012, Ecohydrology)
Several antelope moving through a sagebrush landscape. (Credit: John Bradford, USGS. Public domain.)
Soil water dynamics drive potential big sagebrush migration: Our ecohydrological niche-modeling work linked process-based soil water assessment tools with species distribution models to identify where big sagebrush distribution may shift upslope and northward in coming decades. (See Schlaepfer et al 2012 Ecography.)
Interactions between climate and vegetation can have unexpected impacts on patterns of moisture availability: Our work characterized how disturbances that alter the vegetation in big sagebrush ecosystems can influence the water yield of these widespread ecosystems and modify the water available to regenerating plants. (See Bradford et al. 2014 Ecosystems, 2014 Journal of Ecology).
Climate change will modify seasonal patterns of water availability in big sagebrush ecosystems: Our research quantified the impacts of altered climate on future ecohydrology across big sagebrush ecosystems. Results suggest that most sites will be wetter in the spring, but drier during the summer, and changes were especially large for mid- to high-elevation sites in the northern half of our study area. Drier summer conditions in high elevation, SB-Montane sites may result in increased habitat suitability for big sagebrush and greater sage-grouse habitat, while those same conditions will likely reduce habitat suitability for the dry ecosystem types. (See Palmquist et al 2016 and In Review.)
Future Directions
Forecasting big sagebrush plant community composition and vegetation structure: This work integrates detailed projections of soil moisture availability into plant community models to assess multi-decadal impacts of changing climate and disturbance regimes in core sage grouse habitats.
Assessing the future of big sagebrush regeneration: Building on past findings, this project is describing potential future distribution of big sagebrush as well as potentially important invasive plant species, and quantifying how climate change may impact natural big sagebrush regeneration.
Projecting the impact of climate change on soil moisture and temperature: Recent work (Chambers et al, 2014 RMRS-GTR-326) has identified links between sagebrush ecosystem resistance/resilience and soil temperature and moisture conditions. This project is quantifying how changing climate will alter the distribution of temperature and moisture regimes.
Dead, leafless sagebrush in Wyoming. (Credit: John Bradford, USGS. Public domain.)
Characterizing environmental controls over big sagebrush mortality: Widespread plant mortality events associated with recent drought have highlighted the potential vulnerability of water-limited ecosystems to the warmer and seasonally dryer climate predicted under most future climate change scenarios. Recent work has indicated that woody plant mortality is closely linked to dynamics and availability of soil moisture, and that climate change is likely to elevate the risk of mortality for woody plants, especially in much of the western U.S. This project is investigating a recent big sagebrush mortality event in Wyoming to identify controls and forecast the implications for the sustainability of sagebrush ecosystems.
Validating models with experiments - spatial varaibility in big sagebrush ecosystem response: Relatively little is known about how sagebrush genetic variation will interact with climate, soils, and disturbance to determine future changes in big sagebrush plant communities. This project would implement a distributed network of manipulative field experiments to quantify local adaptation, variation in demographic rates and growth-climate relationships across a species' distribution, and the optimal way to mix spatial and temporal patterns with process-level understanding to strengthen ecological forecasts.
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Email: jbradford@usgs.gov
Terrestrial Ecosystems and Restoration
Climate Change and Drought
Hydrology and Geomorphology
Land Use and Energy Development
Threatened and Endangered Species
Below are other science projects associated with this project.
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Colorado Plateau Futures: Understanding Agents of Change on the Colorado Plateau to Facilitate Collaborative Adaptation
The objective of this interdisciplinary research effort is to 1) characterize agents of change important to land management decision makers on the Colorado Plateau; 2) identify and analyze relationships between agents of change and key landscape attributes and processes; 3) collectively assess the influence of agents of change and attributes and processes on the services provided by the...
Contacts: John Bradford, Mike Duniway, Ph.D., Rudy Schuster, Ph.D., Nina Burkardt, Eric Larson
Attribution: Southwest Biological Science Center
Date published: February 28, 2017
Southwest Energy Development and Drought (SWEDD)
Deserts of the southwestern US are replete with oil and gas deposits as well as sites for solar, wind, and geothermal energy production. In the past, many of these resources have been too expensive to develop, but increased demand and new technologies have led to an increase in exploration and development. However, desert ecosystems generally have low resilience to disturbance. More frequent,...
Contacts: Jayne Belnap, Mike Duniway, Ph.D., Travis W Nauman, Ph.D., Sasha Reed, Ph.D., Seth Munson, Terry Arundel, John Bradford
Attribution: Environments Program, Southwest Biological Science Center
Date published: December 15, 2016
Dryland Forest Sustainability
Forests in the semiarid southwestern U.S. are expected to be highly vulnerable to increasing aridity anticipated with climate change. In particular, low elevation forests and the processes of tree regeneration and mortality are likely to be highly susceptible to climate change. This work seeks to characterize how, where and when forest ecosystems will change and identify management...
Contacts: John Bradford
Ecohydrology and Climate Change in Drylands
Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. However, climate forecasts in most dryland regions, especially the southwest U.S., call for increasing aridity. Specifically, changing climate will alter soil water availability, which exerts dominant control over ecosystem structure and function in water-limited, dryland ecosystems. This research...
Plant Responses to Drought and Climate Change in the Southwestern United States
Land managers face tremendous challenges in the future as drought and climate change alter the abundance, distribution, and interactions of plant species. These challenges will be especially daunting in the southwestern US, which is already experiencing elevated temperatures and prolonged droughts, resulting in reduced soil moisture in an already water-limited environment. These changes will...
Contacts: Seth Munson
Aeolian Dust in Dryland Landscapes of the Western United States
Dust emission caused by wind erosion has received considerable attention because of its far-reaching effects on ecosystems, including the loss of nutrients and water-holding capacity from source areas, changes to climate and global energy balance in areas where dust is entrained in the atmosphere, fertilization of terrestrial and marine ecosystems, in addition to decreases in snow albedo,...
RAMPS: Restoration Assessment & Monitoring Program for the Southwest
The Restoration Assessment and Monitoring Program for the Southwest (RAMPS) seeks to assist U.S. Department of the Interior (DOI) and other land management agencies in developing successful techniques for improving land condition in dryland ecosystems of the southwestern United States. Invasion by non-native species, wildfire, drought, and other disturbances are growing...
Contacts: Molly McCormick, Seth Munson, John Bradford
Attribution: Ecosystems, Environments Program, Status and Trends Program, States and Territories, Region 7: Upper Colorado Basin, Southwest Biological Science Center
Chronic Drought Impacts on Colorado Plateau ecosystems (Rain-Out Experiment)
In drylands, chronic reductions in water availability (press-drought) through reduced precipitation and increased temperatures may have profound ecosystem effects, depending on the sensitivities of the dominant plants and plant functional types. In this study, we are examining the impacts of moderate, but long-term chronic drought using a network of 40 drought shelters on the Colorado Plateau...
Contacts: Mike Duniway, Ph.D., Jayne Belnap, David Hoover
Colorado Plateau Extreme Drought in Grassland Experiment (EDGE)
In drylands, short-term extreme droughts can have profound ecosystem effects, depending on the timing (seasonality) of drought and the sensitivities of the dominant plants and plant functional types. Past work suggests that cool season drought may disproportionately impact regionally important grass and shrub species. In this study, we are examining the impacts of extreme seasonal drought on...
Below are publications associated with this project.
Select Year2016 (1)2015 (1)2014 (3)2012 (1)
Select TypeArticle (6)
Mid-latitude shrub steppe plant communities: Climate change consequences for soil water resources
In the coming century, climate change is projected to impact precipitation and temperature regimes worldwide, with especially large effects in drylands. We use big sagebrush ecosystems as a model dryland ecosystem to explore the impacts of altered climate on ecohydrology and the implications of those changes for big sagebrush plant communities...
Palmquist, Kyle A.; Schlaepfer, Daniel R.; Bradford, John B.; Lauenroth, Willliam K.
Attribution: Southwest Biological Science Center, Ecosystems, Sage-grouse & Sagebrush Ecosystem, Southwest, United States of America
Palmquist, K.A., Schlaepfer, D.R., Bradford, J.B., and Lauenroth, W.K., 2016, Mid-latitude shrub steppe plant communities: Climate change consequences for soil water resources: Ecology, v. online, http://onlinelibrary.wiley.com/doi/10.1002/ecy.1457/full and http://dx.doi.org/10.1002/ecy.1457.
Simulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts
Many semi-arid plant communities in western North America are dominated by big sagebrush. These ecosystems are being reduced in extent and quality due to economic development, invasive species, and climate change. These pervasive modifications have generated concern about the long-term viability of sagebrush habitat and sagebrush-obligate wildlife...
Schlaepfer, Daniel R.; Taylor, Kyle A.; Pennington, Victoria E.; Nelson, Kellen N.; Martin, Trace E.; Rottler, Caitlin M.; Lauenroth, William K.; Bradford, John B.
Schlaepfer, D.R., Taylor, K.A., Pennington, V.E., Nelson, K.N., Martyn, T.E., Rottler, C.M., Lauenroth, W.K., and Bradford, J.B., 2015, Simulated big sagebrush regeneration supports predicted changes at the trailing and leading edges of distribution shifts: Ecosphere, vol. 6, no. 1, article 3, http://dx.doi.org/10.1890/ES14-00208.1.
Shifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance
Summary 1. Terrestrial vegetation influences hydrologic cycling. In water-limited, dryland ecosystems, altered ecohydrology as a consequence of vegetation change can impact vegetation structure, ecological functioning and ecosystem services. Shrub steppe ecosystems dominated by big sagebrush (Artemisia tridentata) are widespread across western...
Bradford, John B.; Schlaepfer, Daniel R.; Lauenroth, William K.; Burke, Ingrid C.
Attribution: Southwest Biological Science Center, Ecosystems, Southwest
Bradford, J.B., Schlaepfer, D.R., Lauenroth, W.K., and Burke, I.C., 2014, Shifts in plant functional types have time-dependent and regionally variable impacts on dryland ecosystem water balance: Journal of Ecology, vol. 102, no. 6, p. 1408-1418, http://dx.doi.org/10.1111/1365-2745.12289.
Ecohydrology of dry regions: storage versus pulse soil water dynamics
Although arid and semiarid regions are defined by low precipitation, the seasonal timing of temperature and precipitation can influence net primary production and plant functional type composition. The importance of precipitation seasonality is evident in semiarid areas of the western U.S., which comprise the Intermountain (IM) zone, a region that...
Lauenroth, William K.; Schlaepfer, Daniel R.; Bradford, John B.
Lauenroth, W.K., Schlaepfer, D.R., and Bradford, J.B., 2014, Ecohydrology of Dry Regions: Storage versus Pulse Soil Water Dynamics: Ecosystems, vol. 17, no. 8, p.1469-1479, http://dx.doi.org/ 10.1007/s10021-014-9808-y.
Ecohydrology of adjacent sagebrush and lodgepole pine ecosystems: the consequences of climate change and disturbance
Sagebrush steppe and lodgepole pine forests are two of the most widespread vegetation types in the western United States and they play crucial roles in the hydrologic cycle of these water-limited regions. We used a process-based ecosystem water model to characterize the potential impact of climate change and disturbance (wildfire and beetle...
Bradford, John B.; Schlaepfer, Daniel R.; Lauenroth, William K.
Ecohydrology of adjacent sagebrush and lodgepole pine ecosystems: the consequences of climate change and disturbance; 2014; Article; Journal; Ecosystems; Bradford, John B.; Schlaepfer, Daniel R.; Lauenroth, William K.
Consequences of declining snow accumulation for water balance of mid-latitude dry regions
Widespread documentation of positive winter temperature anomalies, declining snowpack and earlier snow melt in the Northern Hemisphere have raised concerns about the consequences for regional water resources as well as wildfire. A topic that has not been addressed with respect to declining snowpack is effects on ecosystem water balance. Changes in...
Schlaepfer, Daniel R.; Lauenroth, William K.; Bradford, John B.
Consequences of declining snow accumulation for water balance of mid-latitude dry regions; 2012; Article; Journal; Global Change Biology; Schlaepfer, Daniel R.; Lauenroth, William K.; Bradford, John B.
Below are partners associated with this project.