Prioritizing conifer removal for multi-species outcomes
Wildlife management is frequently conducted to benefit a single species, despite evidence that suggests such an approach often fails to adequately address the needs of other species within a region. Managing for multiple species’ habitat requirements is even more critical when large scale habitat management efforts change vegetation conditions at the landscape scale, or when management occurs at the intersection of multiple ecosystems. In these cases, there are trade-offs among species which may use the habitat before or after management actions. To address the need to manage for multiple species, we developed a framework for prioritizing restoration sites to achieve multi-species benefits across ecosystems. We demonstrate the effectiveness of such an approach, using a case study in which we prioritized sites for mechanical removal of pinyon and juniper trees (hereafter, “conifer removal”) to restore sagebrush ecosystems. We compare predicted songbird populations for six different species following simulated conifer removal at sites prioritized to benefit single species, multiple species within a single ecosystem, or multiple species associated with the two different ecosystems.
Diversity in physical attributes, behavioral patterns, and life histories among wildlife species helps shape the rich communities we see around us. However, this diversity results in different species thriving in different ecological systems across the landscape. As a result, management actions which alter vegetation across the landscape almost certainly result in trade-offs across species – with some species benefitting from changes in vegetation while others are negatively affected. As more and more wildlife species continue to decline globally, the need to carefully and effectively manage the land to support the full complement of species increases.
The interface between sagebrush ecosystems and pinyon-juniper woodlands in the western United States represents one system where vegetation management is occurring that is likely resulting in species and ecosystem trade-offs. Managers are currently racing to help prevent the loss and degradation of sagebrush ecosystems and to bolster dwindling populations of sage-grouse which rely upon healthy sagebrush systems. Land conversion, the spread of exotic grasses, changes in grazing practices, energy development, and a changing climate have collectively reduced the quantity and quality of sagebrush habitat on the landscape, resulting in these sage-grouse population declines. Additionally, pinyon pines and juniper trees have been expanding into sagebrush ecosystems where they were not present a few decades ago, further reducing the amount of quality sage-grouse habitat. To help maintain important sagebrush habitat and conserve the greater sage-grouse, managers are working to remove these encroaching trees from areas that currently support sagebrush. However, there is growing evidence that removing these trees from the landscape may negatively affect species associated with pinyon-juniper woodlands.
One species which relies upon the pinyon pine and juniper trees that are being removed is the pinyon jay. Pinyon jays have been rapidly declining since at least the 1960’s, to the point where the species has recently been proposed for listing under the Endangered Species Act. Thus, management efforts to bolster declining populations of greater sage-grouse may be having undesired effects on the declining pinyon jay, resulting in uncertainty among managers regarding what management actions should be employed where, to concurrently support both these declining species.
Our Research
To address this management conundrum, USGS scientists developed a suite of models which identify vegetation and environmental characteristics likely to support high densities of six songbird species, including three sagebrush-associated species (Brewer’s sparrow, sagebrush sparrow, and sage thrasher) and three pinyon-juniper associated species (Bewick’s wren, gray flycatcher, and pinyon jay). The developed density-habitat relationship models can improve our understanding of how these species are likely to respond to conifer removal across much of the West. Model predictions of species responses to conifer removal across the landscape can be incorporated into a framework to identify sites where the removal of pinyon and juniper trees is likely to result in the largest improvements of sagebrush songbird habitat while minimizing potential habitat loss to pinyon-juniper associated species.
Using this framework, informed by the predicted changes in songbird densities from the density-habitat relationship models, we explored how conifer management occurring within priority areas for sage-grouse conservation in eastern Utah (Figure 1) is likely to affect both sagebrush and pinyon-juniper associated songbird species. We found when conifer removal in this region was targeted to benefit just one sagebrush-associated species (Brewer’s sparrow), it resulted in the worst outcomes for all five other species considered. In contrast, when conifer removal sites were prioritized to benefit the three sagebrush-associated species equally, all species except the Brewer’s sparrow were expected to have larger populations in the study area. Thus, specifically incorporating multiple species in land management prioritization efforts may result in improved conservation outcomes for a more complete suite of species inhabiting a region.
Conservation Applications
- The prioritization framework described here can be used to optimize management across large geographic extents. After identifying priority areas for conservation action, regional managers can allocate resources to areas where we expect the largest return on investment; ensuring the right folks in the right places have the resources necessary to effectively manage the landscape.
- Managers can target conifer removal projects within sites selected by this framework to meet various multi-species or even multi-ecosystem objectives.
Next Steps
We hope to adapt and expand this framework in the future to prioritize conifer removal efforts in other regions and to better address specific manager objectives.
Modeling Songbird Density-Habitat Relationships to Predict Population Responses to Environmental Change Within Pinyon-juniper and Sagebrush Ecosystems
Wildlife management is frequently conducted to benefit a single species, despite evidence that suggests such an approach often fails to adequately address the needs of other species within a region. Managing for multiple species’ habitat requirements is even more critical when large scale habitat management efforts change vegetation conditions at the landscape scale, or when management occurs at the intersection of multiple ecosystems. In these cases, there are trade-offs among species which may use the habitat before or after management actions. To address the need to manage for multiple species, we developed a framework for prioritizing restoration sites to achieve multi-species benefits across ecosystems. We demonstrate the effectiveness of such an approach, using a case study in which we prioritized sites for mechanical removal of pinyon and juniper trees (hereafter, “conifer removal”) to restore sagebrush ecosystems. We compare predicted songbird populations for six different species following simulated conifer removal at sites prioritized to benefit single species, multiple species within a single ecosystem, or multiple species associated with the two different ecosystems.
Diversity in physical attributes, behavioral patterns, and life histories among wildlife species helps shape the rich communities we see around us. However, this diversity results in different species thriving in different ecological systems across the landscape. As a result, management actions which alter vegetation across the landscape almost certainly result in trade-offs across species – with some species benefitting from changes in vegetation while others are negatively affected. As more and more wildlife species continue to decline globally, the need to carefully and effectively manage the land to support the full complement of species increases.
The interface between sagebrush ecosystems and pinyon-juniper woodlands in the western United States represents one system where vegetation management is occurring that is likely resulting in species and ecosystem trade-offs. Managers are currently racing to help prevent the loss and degradation of sagebrush ecosystems and to bolster dwindling populations of sage-grouse which rely upon healthy sagebrush systems. Land conversion, the spread of exotic grasses, changes in grazing practices, energy development, and a changing climate have collectively reduced the quantity and quality of sagebrush habitat on the landscape, resulting in these sage-grouse population declines. Additionally, pinyon pines and juniper trees have been expanding into sagebrush ecosystems where they were not present a few decades ago, further reducing the amount of quality sage-grouse habitat. To help maintain important sagebrush habitat and conserve the greater sage-grouse, managers are working to remove these encroaching trees from areas that currently support sagebrush. However, there is growing evidence that removing these trees from the landscape may negatively affect species associated with pinyon-juniper woodlands.
One species which relies upon the pinyon pine and juniper trees that are being removed is the pinyon jay. Pinyon jays have been rapidly declining since at least the 1960’s, to the point where the species has recently been proposed for listing under the Endangered Species Act. Thus, management efforts to bolster declining populations of greater sage-grouse may be having undesired effects on the declining pinyon jay, resulting in uncertainty among managers regarding what management actions should be employed where, to concurrently support both these declining species.
Our Research
To address this management conundrum, USGS scientists developed a suite of models which identify vegetation and environmental characteristics likely to support high densities of six songbird species, including three sagebrush-associated species (Brewer’s sparrow, sagebrush sparrow, and sage thrasher) and three pinyon-juniper associated species (Bewick’s wren, gray flycatcher, and pinyon jay). The developed density-habitat relationship models can improve our understanding of how these species are likely to respond to conifer removal across much of the West. Model predictions of species responses to conifer removal across the landscape can be incorporated into a framework to identify sites where the removal of pinyon and juniper trees is likely to result in the largest improvements of sagebrush songbird habitat while minimizing potential habitat loss to pinyon-juniper associated species.
Using this framework, informed by the predicted changes in songbird densities from the density-habitat relationship models, we explored how conifer management occurring within priority areas for sage-grouse conservation in eastern Utah (Figure 1) is likely to affect both sagebrush and pinyon-juniper associated songbird species. We found when conifer removal in this region was targeted to benefit just one sagebrush-associated species (Brewer’s sparrow), it resulted in the worst outcomes for all five other species considered. In contrast, when conifer removal sites were prioritized to benefit the three sagebrush-associated species equally, all species except the Brewer’s sparrow were expected to have larger populations in the study area. Thus, specifically incorporating multiple species in land management prioritization efforts may result in improved conservation outcomes for a more complete suite of species inhabiting a region.
Conservation Applications
- The prioritization framework described here can be used to optimize management across large geographic extents. After identifying priority areas for conservation action, regional managers can allocate resources to areas where we expect the largest return on investment; ensuring the right folks in the right places have the resources necessary to effectively manage the landscape.
- Managers can target conifer removal projects within sites selected by this framework to meet various multi-species or even multi-ecosystem objectives.
Next Steps
We hope to adapt and expand this framework in the future to prioritize conifer removal efforts in other regions and to better address specific manager objectives.