99th ESA Annual Meeting (August 10 -- 15, 2014)

SYMP 5

Extreme Weather and Climate Events: Understanding and Adapting to Ecosystem Responses

A key facet of climate change is increased climatic variability. A special report of the Intergovernmental Panel on Climate Change issued in 2012, “Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation” recognized that some types of extreme weather and climate events are likely to increase in frequency or magnitude. General circulation models predict that climate change will result in concurrent drying and warming in certain regions, as well as altered precipitation regimes characterized by more intense precipitation events and longer, more severe droughts. Despite widespread recognition of increasing climatic variability and advancements in our ability to quantify and predict such variability at regional scales, our knowledge of how ecosystems will respond to these changes is more limited. Responses to extreme weather and climate events may vary dramatically among ecosystems. Some may exhibit high resistance because dominant species and communities can persist through extreme events, emerging largely intact and capable of sustaining ecosystem processes when conditions ameliorate. Others may experience significant shifts in species composition, but retain the capacity to sustain desired ecosystem services. However, extreme events also have the potential to fundamentally erode the capacity for ecosystems to provide desired goods and services, potentially due to feedbacks with altered disturbance regimes and/or presence of invasive species. In the western United States, recent droughts have resulted in extensive perennial plant mortality in a wide range of ecosystems, but there is substantial uncertainty regarding subsequent development of altered species assemblages and potential changes in ecosystem function and services. In this symposium, we will present a series of case studies examining ecosystem responses to extreme weather and climate events in the western United States. The symposium will delve into underlying determinants of ecosystem resistance and resilience to extreme events, focusing in particular on the diversity of potential system responses to extreme drought, ranging from strong resistance to varying degrees of resilience, reorganization, and loss of ecosystem services. Effective adaptation to climate change will require explicit consideration of extreme climate events and improved capacity to identify those systems most vulnerable to increased climatic variability. Our ability to predict ecosystem responses to extreme events, in particular the potential feedbacks with disturbance regimes, has fundamental consequences for climate change adaptation by land owners and management agencies. The symposium will conclude with presentations on how land management agencies are incorporating climatic variability into vulnerability assessments and land management planning processes.