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Topographic controls on ecosystem biogeophysics and post-fire succession in semi-arid climates.
George
Azzari, University of California, Irvine, gazzari@uci.edu
(Presenter)
Michael
Goulden, UC Irvine, mgoulden@uci.edu
Ecosystem characteristics such as leaf area, biomass, and plant production vary markedly with aspect and slope in semiarid climates. Lower elevation shrublands in Southern California are dominated by large, dense evergreen shrubs on northern aspects, and by small, sparse drought deciduous shrubs on southern slopes. Our long-term goal is to combine optical and thermal imagery from Landsat and MODIS with in situ observations from flux towers to investigate the relationship between land surface biophysical properties and topography. We would like to understand both how topography influences undisturbed stands and how topography influences the rates and patterns of shrubland recovery from fire. Before addressing these issues, we must correct for the effect of surface exposure on remotely-sensed surface optical brightness. Current methods for topographically correcting imagery proved unsuitable. These approaches use empirical relationships between surface brightness and local slope and aspect, which implicitly removes the true variability related to ecosystem differences with irradiation. We developed a physically-based topographic correction that calculates surface irradiance as a function of slope and aspect. Our model accounts for the angular distribution of direct, diffuse and environmental irradiance over the hemispheric sky as a function of the sun-surface geometry. We will present results of our topographic corrections, along with preliminary analyses of the topographic patterns of shrubland recovery from fire.
Presentation Type: Poster
Session: Poster Session 1-B
(Tue 4:30 PM)
Associated Project(s):
Poster Location ID: 17
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