Multi-Scale, Multi-Temporal Vegetation Mapping and Assessment of Ecosystem Degradation at Gashaka Gumti National Park (Nigeria)

M. Gumnior ； V. Sommer

《Research Journal of Environmental and Earth Sciences》 4卷4期 (2012/04) Pp. 397-412

並列摘要

The study aimed at assessing vegetation cover and status of Gashaka Gumti, Nigeria's largest national park. For this, a traditional pixel-based maximum likelihood classification of a Landsat-7 scene, recorded in December 2000, was carried out. Because simultaneous ground truthing had not been possible, and because of the dynamic nature of the given habitats, different reference data were used to allocate training areas, specify ecological conditions and assess classification accuracy. These included initial unsupervised classifications of multi-temporal images, inter-seasonal field observations and visual interpretations of newly acquired Quickbird mini scenes. The latter served as spatial and temporal scaling tools and were found to be particularly valuable to detect anthropogenic interference. The data reveal that, during most of the dry season, green vegetation is absent in up to one fifth of the park or in about half of the environments of settlement enclaves. This is largely due to human activities such as cattle grazing and burning. Environmental degradation is already detectable in the older imagery, and clearly confirmed as a trend in the newer scenes. The results of this study are suitable to stimulate enhanced and targeted protection measures.

並列關鍵字

Landsat ； maximum likelihood classification ； protected area management ； Quickbird ； vegetation dynamics