Dynamics of vegetation indices in tropical and subtropical savannas defined by ecoregions and Moderate Resolution Imaging Spectroradiometer (MODIS) land cover |
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| Authors: | Michael J Hill Miguel O Román Crystal B Schaaf |
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| Institution: | 1. Department of Earth System Science and Policy , University of North Dakota , Clifford Hall, Stop 9011, 4149 University Avenue, Grand Forks , 58201 , USA hillmj@aero.und.edu;3. NASA Goddard Space Flight Center , Terrestrial Information Systems Branch , Mail Code 614.5, Building 32, S-036F, Greenbelt , 20771 , USA;4. Department of Geography , Boston University , 675 Commonwealth Avenue, Boston , 02215 , USA |
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| Abstract: | In this study, we explored the capacity of vegetation indices derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance products to characterize global savannas in Australia, Africa and South America. The savannas were spatially defined and subdivided using the World Wildlife Fund (WWF) global ecoregions and MODIS land cover classes. Average annual profiles of Normalized Difference Vegetation Index, shortwave infrared ratio (SWIR32), White Sky Albedo (WSA) and the Structural Scattering Index (SSI) were created. Metrics derived from average annual profiles of vegetation indices were used to classify savanna ecoregions. The response spaces between vegetation indices were used to examine the potential to derive structural and fractional cover measures. The ecoregions showed distinct temporal profiles and formed groups with similar structural properties, including higher levels of woody vegetation, similar forest–savanna mixtures and similar grassland predominance. The potential benefits from the use of combinations of indices to characterize savannas are discussed. |
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| Keywords: | savanna vegetation index vegetation structure fractional cover |
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