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Incorporating spatial heterogeneity created by permafrost thaw into a landscape carbon balance estimate
E.
Fay
Belshe, University of Florida, fayray@ufl.edu
(Presenter)
The future carbon (C) balance of high latitude ecosystems is dependent on the sensitivity of biological processes (photosynthesis and respiration) to the physical changes occurring with permafrost thaw. But predicting C exchange in these ecosystems is difficult because the thawing of permafrost is not a uniform and homogeneous process. We measured net ecosystem exchange (NEE) of C using eddy covariance (EC), in a tundra landscape visibly undergoing thaw, during two 6-month campaigns in 2008 and 2009. We developed a spatially explicit quantitative metric of permafrost thaw based on variations in microtopography and incorporated it into an EC carbon flux estimate using a generalized additive model (GAM). This model allowed us to make predictions about C exchange for the landscape as a whole, and for specific landscape patches throughout the continuum of permafrost thaw and ground subsidence. On average between the years, areas with the highest permafrost thaw took up 17.7% more and respired 3.3% more C than the average landscape. Areas with the least thaw took up 15% less and respired 5.1% less than the landscape on average. By incorporating spatial variation into the EC C estimate, we were able to determine how thaw affect C flux. Overall, permafrost thaw increases the amplitude of the C cycle by stimulating both C release and sequestration. As the next step, we are quantifying the spatial distribution and extent of permafrost thaw within the watershed by developing a land cover classification using a combination of elevation, slope, and spectral characteristics of an IKONOS image. Preliminary results indicate that thaw is occurring in areas with the highest organic C content and deepest active layer thawing. Presentation Type: Poster Session: Global Change Impact & Vulnerability (Tue 11:30 AM) Associated Project(s):
Poster Location ID: 112
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