Climate change impacts on vegetation in the San Francisco Bay Area: a novel approach to vulnerability analysis (Invited)
Abstract
Climate change is expected to profoundly impact terrestrial vegetation. Understanding spatial variability of these impacts is critical to development of conservation strategies and projections of ecosystem services under future climates. We present a model of the projected impacts of climate change on the distribution of vegetation types in the San Francisco Bay Area using a novel application of multinomial logistic regression. The output of this method is a vector of the relative probability of occupancy by each of a set of vegetation types, for each pixel in the landscape. This approach models all vegetation types, in contrast to methods that model the distribution of each type or species individually. The overall vulnerability of vegetation to climate change can then be quantified as the change in modeled probabilities between the vectors modeled under present versus future climates. These changes capture the likelihood of long-term climate-driven vegetation change for each pixel, without relying on specific predictions of present and future vegetation types. This measure of vulnerability can be further decomposed as the product of two components, one reflecting the intrinsic sensitivity of the vegetation to climate and the second measuring the exposure to (i.e., magnitude of) climate change. Based on a new set of high-resolution downscaled climate projections for Coastal California, including an estimate of the annual climatic water deficit, we demonstrate that the vulnerability of vegetation distributions is almost entirely due to variation in sensitivity, and not to differences in the magnitude of climate change. Furthermore, there are weak but significant trends towards greater sensitivity on cool, north-facing slopes and in valley bottoms, as well as a bimodal distribution with greater sensitivity under the coolest and warmest summer temperature regimes in the Bay Area. These results do not support a commonly held conviction that cool environments will act as in-situ refugia with reduced impacts on vegetation in the face of 21st century climate change.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFMGC41H..07A
- Keywords:
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- 1630 GLOBAL CHANGE / Impacts of global change;
- 1632 GLOBAL CHANGE / Land cover change