Thursday, August 9, 2007: 1:30 PM-5:00 PM
B3&4, San Jose McEnery Convention Center
Organizer:
Craig D. Allen
Co-organizer:
David D. Breshears
Moderator:
David D. Breshears
Evidence of climate change effects on the biosphere is accumulating rapidly, including recent examples of climate-induced forest dieback. Although relatively few examples of widespread forest dieback events have been documented to-date, some mortality events have had extensive ecological impacts. Increasing numbers of recent studies demonstrate forest stress and dieback at local to regional scales, but currently lacking is a global overview of forest dieback, and sufficient mechanistic knowledge to enable accurate modeling and predictions of climate-induced woody plant mortality. The overall goal of this organized oral session is to present a current synthesis of forest dieback as an emergent global phenomenon, which will include: (1) a globally comprehensive overview and synthesis developed from ongoing research, case studies, and existing literature; (2) continental-scale summaries of mortality patterns and processes of climate-induced dieback from around the world, including detailed case studies; (3) plant physiological perspectives on water use, carbon balance, and resistance to insect attacks, emphasizing current understanding and knowledge gaps; and (4) current and potential applications of available knowledge to regional and global scale modeling and prediction of forest dieback, key areas needed to improve current models, and existing and potential applications to assessments and mitigation of potential climate change impacts. We will evaluate the extent to which recently observed dieback events are unusual relative to historic background patterns.
Our session documents climate-induced forest dieback from all forested continents, including: 1) drought impacts in Patagonia and the Amazon Basin; 2) dieback of multiple forest species in the West African Sahel; 3) dieback of several European species of Pinus and Quercus in multiple mountain ranges across Mediterranean Portugal, Spain, and France; 4) eucalyptus dieback in Australia; and 5) substantial episodes of recent forest mortality in North America from Alaska to Mexico, such as >1,000,000 ha of pinyon (Pinus edulis) dieback in the southwestern US since 2002. These case studies are highly relevant to a broad array of ecologists because they represent vegetation changes in response to climate variation and change that can span across individuals, populations, communities, and ecosystems.