Two articles from the HilleRisLambers lab demonstrate that tree-to-tree interactions are critical to understanding how climate change will influence forests of the Pacific Northwest.
Using 35 years of tree growth data from 15 forest stands at Mt. Rainier National Park, alumnus Kevin Ford (currently a biometrician at the BLM in Portland, OR) and coauthors demonstrate in the Canadian Journal of Forest Research that although tree growth will increase with warming, crowding in dense forests minimize those growth increases for individual trees. Using a seedling transplant experiment (also at Mt. Rainier National Park) reported on in Global Change Biology, alumna Ailene Ettinger (currently a postdoctoral research associate at Tuft and Harvard Universities) and coauthor Janneke HilleRisLambers find that nearby adult trees and dense understories limit the increased growth and survival tree seedlings might otherwise benefit from with climate change, presumably due to lower light levels. However, they also find that tree seedlings actually benefit from crowding at high elevations (near treeline), where canopy trees protect seedlings from prolonged snow. In all, these studies suggest that we cannot ignore how species interact when documenting the biological impacts of climate change.