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Mapping Bush Encroaching Species by Seasonal Differences in Hyperspectral Imagery
Biocentre Klein Flottbek and Botanical Garden, University of Hamburg, Hamburg, Germany
German Remote Sensing Data Center, German Aerospace Center, Oberpfaffenhofen, Germany
Institute of Photogrammetry and Remote Sensing, Vienna University of Technology, Vienna, Austria
* Author to whom correspondence should be addressed.
Received: 15 March 2010; in revised form: 12 April 2010 / Accepted: 19 May 2010 / Published: 27 May 2010
Abstract: Bush encroachment is a form of land degradation prominent worldwide, but particularly present in semi-arid areas. In this study, we mapped the spatial distribution of the two encroacher species, Acacia mellifera and Acacia reficiens,in Central Namibia, based on their different phenological behavior. We used constrained principal curves to extract a one dimensional gradient of phenological change from two hyperspectral images taken in different seasons. Field measurements of species composition and cover values were statistically related to bi-temporal differences in hyperspectral vegetation indices in a direct gradient analysis. The extracted gradient reflected the relationship between species composition and cover values, and the phenological pattern as captured by the image data. Cover values of four dominant plant species were mapped and species responses along the phenological gradient were interpreted.
Keywords: principal curve; constrained ordination; savanna; change detection; vegetation index differencing; bush encroachment; tree-grass ratio; imaging spectroscopy
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MDPI and ACS Style
Oldeland, J.; Dorigo, W.; Wesuls, D.; Jürgens, N. Mapping Bush Encroaching Species by Seasonal Differences in Hyperspectral Imagery. Remote Sens. 2010, 2, 1416-1438.
Oldeland J, Dorigo W, Wesuls D, Jürgens N. Mapping Bush Encroaching Species by Seasonal Differences in Hyperspectral Imagery. Remote Sensing. 2010; 2(6):1416-1438.
Oldeland, Jens; Dorigo, Wouter; Wesuls, Dirk; Jürgens, Norbert. 2010. "Mapping Bush Encroaching Species by Seasonal Differences in Hyperspectral Imagery." Remote Sens. 2, no. 6: 1416-1438.