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How does environmental suitability for pinyon-juniper species shift under future climate conditions?
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See publications from this research describing shifts in environmental suitability for PJ tree species and development of a related climate adaptation framework for PJ woodlands.
Background
Pinyon-juniper (PJ) woodlands cover a large portion of western North America, providing diverse habitat across 3,500 km from Canada to Mexico. PJ woodlands are abundant in may western National Parks, and represent a large proportion of the nation’s mature and old-growth forests. These woodlands provide a wide variety of economic and cultural benefits to rural communities and visitors, including wildlife habitat, recreation, and energy development. However, PJ woodlands are being impacted by altered drought and wildfire patterns and resource managers need information about vulnerability of their PJ woodlands and insights into potential management strategies to enhance resilience of PJ woodlands to these changing conditions. This project is working to fill some of these information gaps by characterizing geographic patterns in the vulnerability of PJ woodlands, and evaluating the potential benefits of management actions like strategic forest thinning.
Objectives & Approach
In this project, we fit species distribution models (SDMs) for nine PJ species and project how environmental suitability in current conditions will change under a variety of future climate scenarios. SDMs are a common approach to support conservation decision making, and our goal was to maximize applicability of our models by assembling a set of dryland-focused predictor variables, using models types that facilitate ecological interpretation, and quantifying robustness in our projections of PJ suitability.
For each PJ species, we compare driving climatic and soil variables and map suitability change for six future emissions-time period scenarios. We assess the amount of area that projected to gain or lose suitability, and summarize range-wide trends in suitability shifts and shrinks. Visualizing trends in suitability for PJ species will help prioritize climate adaptation efforts in these widespread woodlands.
Outcomes
PJ species’ suitabilities respond to many temperature and precipitation covariates expected to change in the future. Some species, such as J. osteosperma and J. californica, are projected to experience modest decreases in suitable areas that are balanced by increases elsewhere, indicating ability to shift distribution in the future. Others, such as J. monosperma and J. scopulorum, are projected to shrink in response to widespread suitability declines that are not compensated by newly suitable area. Highly managed species, such as P. edulis, P. monophylla, J. osteosperma and J. occidentalis, all vary in where and how much land area is projected to gain suitability to enable distribution shifts under future climate.
We found that species were projected to experience more losses than gains in suitability, for overall range shrinks rather than shifts. Land managers have the capacity to increase woodland resilience to drought, and our results can inform range-wide management planning and conservation efforts in PJ woodlands.
Data for these projections can be accessed on ScienceBase, at the link here.
How can these suitability projections be used to inform long-term climate adaptation planning?
How can these suitability projections be used to inform long-term climate adaptation planning?
Individual ➡️ Community-level projections
Individual ➡️ Community-level projections
To expand on these modeling efforts informing woodland management, we combine suitability projections for all PJ species and assess community suitability across time and space. We further integrate community suitability results with additional landscape metrics, creating an example framework to prioritize management actions across the broad range of woodland ecosystems.
Approach
Approach
We merge projections of future environmental suitability for nine PJ species using a distance-weighted approach, and then combine with measures of wildfire risk and locations of mature & old-growth (MOG) woodlands to assess spatial variation in PJ woodlands with differing threats and management opportunities. We calculate an additional metric of a location's capacity to act either as climate refugia for the area's current species composition or as a climatically favorable location for species not yet present, highlighting opportunities for management to assist species movements.
We integrate community suitability with wildfire risk, locations of MOG woodland, and potential refugia in bivariate analyses to identify spatial overlap of these metrics and visualize the mosaic of landscape conditions in which management approaches may vary. Finally, we combine these data in an example framework (below) to show how managers may plan for future climate conditions in an anticipatory management context.
Implications
Implications
The range of PJ ecosystems is vast and conservation efforts may be spread across thousands of kilometers. In an era of increasing management challenges and contracting resources, a strategic landscape approach can help maximize the value of management resources by ensuring they are invested in the most optimal locations for long-term benefit.
Despite broad community suitability declines under future climate conditions, some locations may act as climate refugia where future climate conditions can support current PJ woodland composition and structure. Furthermore, understanding how these locations may vary in burn probability can guide management decision making between many potential choices to preserve woodland composition, plan for assisted species migrations, or accept shifts towards other ecosystem types.
Data for these analyses can be found linked here.
Collaborators
Brad Butterfield - Northern Arizona University, Department of Biological Sciences and Center for Environmental Research
Megan Swan, Jodi Norris - National Park Service, South Colorado Plateau Inventory & Monitoring Network
Kim Hartwig - National Park Service
Ian Barrett, Michele Crist - BLM National Interagency Fire Center
Chris Domschke - BLM Oregon / Washington State Office
Support
USGS Climate Adaptation Science Centers
Bureau of Land Management
National Park Service - Natural Resource Stewardship and Science Directorate
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