Background

Pinyon-juniper ecosystems cover a large portion of western North America, providing diverse habitat across 3,500 km from Canada to Mexico. PJ woodlands have undergone a mix of ecological and anthropogenic changes over the past century, with tree response ranging from widespread mortality to expansion into new biomes. Future climate change is likely to shift suitable areas for PJ species, which may threaten the integrity of our irreplaceable national park and public lands, as well as millions of acres of old-growth and mature forest. Land and park managers across the West could greatly benefit from projections of long-term suitability of PJ species, but existing studies lack either the west-wide geographic scope or use only one or a few future climate models, limiting the amount of confidence managers can place on results under uncertain climate change. 

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.