Plant community assembly and disassembly with climate change

University Of Washington, Seattle WA

Investigators

Abstract

How strongly does climate influence the composition of ecological communities? If climate is the predominant force structuring communities, climate warming should predictably result in the loss of cold-adapted species at the expense of warm-adapted species in local communities. Alternatively, if regional climate doesn't strongly structure local communities, then species composition may not change much with climate change. However, an apparent lack of change in the species composition of local communities experiencing climate warming can also arise from a limited ability of species to shift their geographic ranges, e.g., slow rate of dispersal. Unfortunately, these two possibilities have very different implications; the first suggests communities may be somewhat resilient to climate change, while the latter implies community sensitivity, especially as climate change accelerates. This research will test the importance of community resilience vs. sensitivity to recent and future climate change, by examining unique historic data sets of plant species composition collected across regional climatic gradients in two Pacific Northwest National Parks. The project will contribute to our understanding of the consequences of climate change and communicate this information to National Park Service and other resource managers in the Pacific Northwest. This project will also provide opportunities for student research and training that will strengthen the scientific workforce. This project will make progress on the problem of predicting change in plant communities with climate change given apparent stasis, despite the inherent challenges of differentiating drivers with similar expected outcomes. Specifically, this project will determine how strongly climate influences plant communities in the mountains of the Pacific Northwest. Hypotheses on relations of community composition and bioclimatic variables will be tested using resurvey data sets of plant community composition originally collected over 30 years ago in two National Parks (North Cascades National Park and Mount Rainier National Park). This historic data will be combined with newly developed joint species distribution models and high resolution data on the landscape features that influence microclimate. Research objectives are to: I. Assess the importance of macro and microclimatic variables for community composition; II. Examine community shifts over the last four decades to determine whether compositional turnover with recent climate change is consistent with climatic buffering (resilience) vs. lagged species responses (sensitivity); and III. Conduct a multi-species seed addition experiment across large-scale and fine-scale climatic gradients to parse out the roles of recruitment limitation and demographic inertia (factors that contributed to time-lagged sensitivity) and macro- or microclimatic buffering (factors that promote resilience to climate change) in the early stages of community assembly.