PJ vulnerability

Background

Pinyon-juniper ecosystems cover a large portion of western North America, providing arid tree habitat across 3,500 km from Canada to Mexico. Future climate change is likely to alter PJ woodland composition, in addition to prior widespread mortality events, which may threaten the integrity of our irreplaceable national park lands and millions of acres of old-growth and mature forest type. Simultaneously, PJ species interact and conflict with adjacent biome types, further complicating effective management that balances habitat needs across western North America. 

Land and park managers across the Colorado Plateau 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 landscape suitability under current climate conditions will change under a variety of future climate scenarios. SDMs are a fairly 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 four future emissions-time period scenarios. We contrast the amount of area that projected to gain or lose suitability, and summarize range-wide trends in suitability shifts and shrinks.