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SRTM-DEM and Landsat ETM+ data for mapping tropical dry forest cover and biodiversity assessment in NicaraguaAuthor(s): S.E. Sesnie; S.E. Hagell; S.M. Otterstrom; C.L. Chambers; B.G. Dickson
Source: Revista Geografica Academica. 2(2): 53-65.
Publication Series: Scientific Journal (JRNL)
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DescriptionTropical dry and deciduous forest comprises as much as 42% of the world’s tropical forests, but has received far less attention than forest in wet tropical areas. Land use change threatens to greatly reduce the extent of dry forest that is known to contain high levels of plant and animal diversity. Forest fragmentation may further endanger arboreal mammals that play principal role in the dispersal of large seeded fruits, plant community assembly and diversity in these systems. Data on the spatial arrangement and extent of dry forest and other land cover types is greatly needed to enhance studies of forest fragmentation effects on animal populations. To address this issue, we compared two Random Forest decision tree models for land cover classification in a Nicaraguan tropical dry forest landscape with and without the use of terrain variables derived from Space Shuttle Radar and Topography Mission digital elevation data (SRTM-DEM). Landsat Enhanced Thematic Mapper (ETM+) bands and vegetation indices were the principle source of spectral variables used. Overall classification accuracy for nine land cover types improved from 82.4% to 87.4% once terrain and spectral predictor variables were combined. Error matrix comparisons showed that class accuracy was significantly greater (z = 2.57, p-value < 0.05) with the inclusion of terrain variables (e.g., slope, elevation and topographic wetness index) in decision tree models. Variable importance metrics indicated that a corrected Normalized Difference Vegetation Index (NDVIc) and terrain variables improved discrimination of forest successional types and wetlands in the study area. Results from this study demonstrate the capability of terrain variables to enhance land cover classification and habitat mapping useful to biodiversity assessment in tropical dry forest.
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CitationSesnie, S.E.; Hagell, S.E.; Otterstrom, S.M.; Chambers, C.L.; Dickson, B.G. 2008. SRTM-DEM and Landsat ETM+ data for mapping tropical dry forest cover and biodiversity assessment in Nicaragua. Revista Geografica Academica. 2(2): 53-65.
KeywordsSTRM-DEM, Landsat ETM+, Random Forest classifier, tropical dry forest, land cover
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