Changes in Sagebrush Ecosystem Connectivity
Disturbances, management, and changing environmental conditions have reshaped the sagebrush biome within the western United States. As a result, sagebrush cover and configuration have varied over space and time, influencing ecological processes and species' use of the landscape. Characterizing changes in sagebrush ecosystem connectivity over time will help us understand the effects of those changes on habitat fragmentation and wildlife population isolation, where actions can be taken to monitor and restore the important habitat connections.
Background
Landscape connectivity describes how the configuration of landscape features facilitate or impede movement of flora and fauna, including organic matter and nutrient exchanges, seed dispersal, and wildlife dispersals and migrations. Linkages within landscapes vary in time and space, supporting diverse ecosystem processes. Connectivity can affect how ecological processes function across landscapes at local and immediate distances, as well as across broad spatial and temporal extents. We investigated spatial and temporal connectivity patterns of the sagebrush biome using a time series (1985-2020) of sagebrush cover (structural change) and spatial pattern analysis to understand how these landscapes and the wildlife they support have changed.
Methods
We assessed connectivity using circuit-theory1 to identify multiple habitat connections across patchy (for example, sagebrush interspersed with bare ground, agriculture, and energy development) and non-patchy (for example, uniform distributions of sagebrush) landscapes. Circuit theory identifies random pathways (connections) between gradients of varying degrees of habitat quality. Between 1985 and 2020, we analyzed patterns of a) connectivity persistence and variability, b) changes and trends of gain or loss, and c) changes in connectivity flow affected by impedance and pathway densities (channelization). Using these results, we evaluated connectivity patterns in greater sage-grouse (Centrocercus urophasianus) priority areas of conservation and areas identified as core sagebrush and growth opportunity areas2 as an example on how the products can inform sagebrush habitat management (Figure 1).
Results
We found that most of the sagebrush biome experienced moderate change, but the amount and type of change varied spatially, indicating that areas differ in the trend direction and magnitude of change. For example, approximately 60% of the biome had moderate or non-persistent connectivity patterns. However, 19.3% of the biome had consistently high connectivity (75% of years), and 20.4% had consistently low connectivity (25% of years).
Research Implications
Understanding connectivity patterns can help reveal how landscape configuration may contribute to an ecosystem's resilience to disturbances, increase our understanding of isolated and recolonized populations, and increase our understanding of adaptation to changing landscapes. Our results characterize spatiotemporal structural connectivity patterns in the sagebrush biome across time and space; therefore, these results may provide important ecological information on sagebrush connectivity persistence that can support targeted management actions to address changing structural connectivity for maintaining functioning connected ecosystems.
Funders
Wyoming State office of the Bureau of Land Management and the U.S. Geological Survey (Ecosystems Mission Area).
Partners
Colorado State University and Bureau of Land Management.
References
- McRae, B.H., Dickson, B.G., Keitt, T.H., Shah, V.B., 2008, Ecology: Using circuit theory to model connectivity in ecology, evolution, and conservation, v.89, no. 10, pp. 2712–2724, https://doi.org/10.1890/07-1861.1.
- 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.
- Greater Sage-Grouse 2015 USFWS Status Review Current Range.
- Buchholtz E.K., O’Donnell M.S., Heinrichs J.A., Aldridge C.L., Land: Temporal Patterns of Structural Sagebrush Connectivity from 1985 to 2020, 2023, v. 12, no. 6(1176), 13p., https://doi.org/10.3390/land12061176.
Disturbances, management, and changing environmental conditions have reshaped the sagebrush biome within the western United States. As a result, sagebrush cover and configuration have varied over space and time, influencing ecological processes and species' use of the landscape. Characterizing changes in sagebrush ecosystem connectivity over time will help us understand the effects of those changes on habitat fragmentation and wildlife population isolation, where actions can be taken to monitor and restore the important habitat connections.
Background
Landscape connectivity describes how the configuration of landscape features facilitate or impede movement of flora and fauna, including organic matter and nutrient exchanges, seed dispersal, and wildlife dispersals and migrations. Linkages within landscapes vary in time and space, supporting diverse ecosystem processes. Connectivity can affect how ecological processes function across landscapes at local and immediate distances, as well as across broad spatial and temporal extents. We investigated spatial and temporal connectivity patterns of the sagebrush biome using a time series (1985-2020) of sagebrush cover (structural change) and spatial pattern analysis to understand how these landscapes and the wildlife they support have changed.
Methods
We assessed connectivity using circuit-theory1 to identify multiple habitat connections across patchy (for example, sagebrush interspersed with bare ground, agriculture, and energy development) and non-patchy (for example, uniform distributions of sagebrush) landscapes. Circuit theory identifies random pathways (connections) between gradients of varying degrees of habitat quality. Between 1985 and 2020, we analyzed patterns of a) connectivity persistence and variability, b) changes and trends of gain or loss, and c) changes in connectivity flow affected by impedance and pathway densities (channelization). Using these results, we evaluated connectivity patterns in greater sage-grouse (Centrocercus urophasianus) priority areas of conservation and areas identified as core sagebrush and growth opportunity areas2 as an example on how the products can inform sagebrush habitat management (Figure 1).
Results
We found that most of the sagebrush biome experienced moderate change, but the amount and type of change varied spatially, indicating that areas differ in the trend direction and magnitude of change. For example, approximately 60% of the biome had moderate or non-persistent connectivity patterns. However, 19.3% of the biome had consistently high connectivity (75% of years), and 20.4% had consistently low connectivity (25% of years).
Research Implications
Understanding connectivity patterns can help reveal how landscape configuration may contribute to an ecosystem's resilience to disturbances, increase our understanding of isolated and recolonized populations, and increase our understanding of adaptation to changing landscapes. Our results characterize spatiotemporal structural connectivity patterns in the sagebrush biome across time and space; therefore, these results may provide important ecological information on sagebrush connectivity persistence that can support targeted management actions to address changing structural connectivity for maintaining functioning connected ecosystems.
Funders
Wyoming State office of the Bureau of Land Management and the U.S. Geological Survey (Ecosystems Mission Area).
Partners
Colorado State University and Bureau of Land Management.
References
- McRae, B.H., Dickson, B.G., Keitt, T.H., Shah, V.B., 2008, Ecology: Using circuit theory to model connectivity in ecology, evolution, and conservation, v.89, no. 10, pp. 2712–2724, https://doi.org/10.1890/07-1861.1.
- 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.
- Greater Sage-Grouse 2015 USFWS Status Review Current Range.
- Buchholtz E.K., O’Donnell M.S., Heinrichs J.A., Aldridge C.L., Land: Temporal Patterns of Structural Sagebrush Connectivity from 1985 to 2020, 2023, v. 12, no. 6(1176), 13p., https://doi.org/10.3390/land12061176.