| Summary: | NSF grant #ARC-0806506: "Modeling patch-scale expansion of shrubs." Dr. David M. Cairns is the Principal Investigator and is a Professor of Geography in the Department of Geography at Texas A&M University Adam T. Naito is a PhD candidate in the Department of Geography at Texas A&M University, working under the supervision of Dr. Cairns. The expansion of shrubs in the northern Brooks Range and North Slope uplands is a phenomenon that has occurred over much of the 20th century. Its historic spatial characteristics and environmental influences, however, remain understudied. Naito's dissertation research addresses this issue in two ways by developing: 1) time-series maps of historic shrub expansion based upon vertical aerial photographs (acquired from the United States Geological Survey (USGS) Earth Resources and Observing System (EROS)) and high-resolution satellite imagery, and 2) a spatially-explicit, stochastic simulation model that simulates shrub expansion based upon parameters relating to topographically-derived hydrological characteristics, shrub growth rates, and reproductive characteristics. Analysis of the model output results will foster hypothesis generation regarding environmental influences on shrub expansion. This archive contains compressed GeoTIFFs of the time-series maps of shrub expansion created for the grant award noted above. These are suitable for display in any GIS that will recognize GeoTIFF format files.These maps were generated using an semi-automatic unsupervised ISODATA classification of historic black-and-white, color-infrared, and high-resolution satellite imagery (IKONOS/GeoEye/QuickBird). Classification was manually corrected to remove shadows, non-shrub features, etc. that may have been classified as shrub.
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