COS 260-2 - Potential shifts in pinyon-juniper distributions under future climate: implications for Southwestern US landscapes.

Abstract: Pinyon-juniper (PJ) woodlands are among the most widespread vegetation types in the western U.S., providing habitat, supporting recreation, grazing, and cultural/spiritual enrichment. Like many dryland ecosystems across the west, PJ woodlands face an uncertain future under warmer temperatures and altered precipitation regimes. Mass mortality events have raised concerns over the viability of PJ populations in the Southwest, while simultaneous expansion into shrublands and grasslands elsewhere may suggest widespread range shifts. In both cases, conservation efforts to manage PJ woodlands would benefit from maps depicting how species suitability is projected to change under future climate scenarios.

In this study, we assess current and future habitat suitability for pinyon-juniper species across the US West using species distribution models (SDMs) and climate projections based on 11 global climate models driven by two emission scenarios. Our modeling process was conducted with the goal of integrating results into management decisions by creating a set of climate and soil predictors specifically for dryland ecosystems, ensuring our model is sensitive to and operates well under climate change, maximizing replicability using a variable reduction technique, and emphasizing landscape-scale interpretability. Our results show a variety of species’ responses to future climate and suggest moderate range shifts that are consistent across climate models. We specifically highlight potential for PJ transformation on the Colorado Plateau and discuss how adaptive management strategies may be needed to maintain ecosystem services on western US landscapes.