Changing forest-woodland-savanna mosaics in Uganda: with implications for conservation

Nangendo, G. (2005). PhD thesis, Wageningen University; ITC Dissertation number 123, International Institute for Geo-information Science & Earth Observation, Enschede, The Netherlands, ISBN 90-8504-163-5; 139 pp. (summaries in English and Dutch)

Forest-Woodland-Savanna (FWS) mosaics are complex, highly varied and dynamic landscapes. Until recently, they were considered poor in terms of biodiversity. Consequently, only few scientific studies have been done on them and little attention has been paid to their conservation. The aim of this study was, therefore, to assess the spatial and temporal variation in the FWS vegetation. Budongo Forest Reserve, located in northwestern Uganda, was the main study site.

Five vegetation cover classes (VCC) and a burnt area cover class were identified and were best classified using Spectral Angle Mapper (SAM) combined with an Expert System (overall accuracy was 94.6%). The VCC were well distinguishable in terms of species composition and vegetation structure. Many tree species, however, occurred in more than one VCC and the vegetation showed a gradient in species composition. Fire was identified as the major factor influencing woody plant variation. Along a succession gradient, adults and juveniles of some of the species were found at different locations.

Between 1985 and 2002, the woodland-savanna vegetation increased in 15.1% of the area and decreased in another 14.3%. Three VCC subjected to a similar fire regime for over 46 years also showed a convergence in woody plant composition.

The observed variation along the FWS gradient indicates that each part of the FWS mosaic is essential for the maintenance of the overall diversity within the mosaic. To conserve mosaics, the existing vegetation variation and their spatial and temporal interrelationships need to be conserved. Purposeful fire management is an essential element of this variation.

Key-words: Biodiversity, conservation, vegetation dynamics, forest 

Grace Nangendo defended her thesis on June 01, 2005 at the ITC, Enschede

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