Vegetation in Tanzania : assessing long term trends and effects of protection using satellite imagery

Abstract Using normalized difference vegetation index (NDVI) imagery, we examined changes in vegetative cover across Tanzania and found that overall greenness increased over 13 years from 1982 to 1994. We then assigned 8 km pixels to different habitat types using a vegetation map compiled from Landsat satellite imagery between 1978 and 1982. We found that woodland and forest pixels increased in greenness but that swamp pixels showed a marked decline in vegetative cover. National parks and game reserves, which have heavy restrictions on resource extraction and on-site patrols, both showed increases in vegetative cover, particularly for woodland pixels. Forest reserves, which are explicitly designed for forest protection but do not have on-site patrols, did no better than lands under no legal protection at all. Game controlled areas, which allow for settlement, cattle grazing, and hunting, suffered worse habitat degradation than areas with no legal protection, with bushlands, grasslands, swamps and “other lands” pixels faring worse than baseline measures. These results show that complete protection and on-site policing are key elements in enhancing vegetation health in this region of tropical Africa, paralleling results for mammals in the same area.

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