The impact of anthropogenic land use change on the protected areas of the Kilombero catchment, Tanzania

The Kilombero floodplain in Tanzania is one of the largest wetlands in Africa and at the same time one of the focus regions for agricultural production of the Tanzanian government. Whereas the floodplain received a lot of attention from the scientific community over the past years, little is known about the state of the entire catchment, in particular of its protected areas. We have evaluated how human impact - expressed here as land with specific anthropogenic land use (e.g. settlements, agricultural areas, teak plantations) - varies across the different protection categories (e.g. national park, game reserve, wildlife management area etc.). For that, first we used long-term land use/land cover (LULC) change maps of the Kilombero catchment to assess the human impact per protected area category. Second, we calculated building density per square kilometer as an indicator of existing human pressure. Third, from the anthropogenic LULC area in 2014 we predicted those areas that show similar morphometric, edaphic and bio-climatic conditions in the study region using the maximum-entropy algorithm (maxEnt). Results of the analysis reveal that in 2014 almost half of the Kilombero Ramsar site was covered by anthropogenic land uses, resulting in a share of 17% for all protected areas. Protected areas with strict use regulations such as national parks and game reserves showed virtually no anthropogenic land use throughout the observation period of 40 years (1974-2014), whereas LULC change was higher in unprotected areas. The increase of agricultural land was mainly at the expense of open woodland, floodplain grassland and savanna grassland. Our results further demonstrate that approx. 670.000 ha of the Kilombero catchment comprise similar conditions as the currently used land within the catchment. However, two thirds of it is located in protected areas, causing challenges for conservation. This is the first study exploring the effect of protected areas of the Kilombero catchment from a LULC and modeling perspective.