US forest response to projected climate-related stress: a tolerance perspective.
Although it is widely recognized that climate change will require a major spatial reorganization of forests, our ability to predict exactly how and where forest characteristics and distributions will change has been rather limited. Current efforts to predict future distribution of forested ecosystems as a function of climate include species distribution models (for fine-scale predictions) and potential vegetation climate envelope models (for coarse-grained, large-scale predictions). Here, we develop and apply an intermediate approach wherein we use stand-level tolerances of environmental stressors to understand forest distributions and vulnerabilities to anticipated climate change. In contrast to other existing models, this approach can be applied at a continental scale while maintaining a direct link to ecologically relevant, climate-related stressors. We first demonstrate that shade, drought, and waterlogging tolerances of forest stands are strongly correlated with climate and edaphic conditions in the conterminous United States. This discovery allows the development of a tolerance distribution model (TDM), a novel quantitative tool to assess landscape level impacts of climate change. We then focus on evaluating the implications of the drought TDM. Using an ensemble of 17 climate change models to drive this TDM, we estimate that 18% of US ecosystems are vulnerable to drought-related stress over the coming century. Vulnerable areas include mostly the Midwest United States and Northeast United States, as well as high-elevation areas of the Rocky Mountains. We also infer stress incurred by shifting climate should create an opening for the establishment of forest types not currently seen in the conterminous United States.
Department of Mathematics & Statistics, Washington State University Vancouver, 14204 NE Salmon Creek Ave, Vancouver, WA, 98686, USA.
Jean
0000-0003-4279-4980
J
Liénard
School of the Environment, Washington State University Vancouver, 14204 NE Salmon Creek Ave, Vancouver, WA, 98686, USA.
John
J
Harrison
Department of Mathematics & Statistics, Washington State University Vancouver, 14204 NE Salmon Creek Ave, Vancouver, WA, 98686, USA.
Nikolay
N
Strigul
D002980:Climate; D057231:Climate Change; D055864:Droughts; D017753:Ecosystem; D065928:Forests; D014481:United States
climate change; drought, shade and waterlogging tolerance indices; drought-related stress; forested ecosystems; tolerance distribution model