Woody vegetation structure and composition along a protection gradient in a miombo ecosystem of western Tanzania.
Banda-Sakala, Tasila*,1, Schwartz, Mark 2, Caro, Tim1, 3, 1 Dept. of Wildlife, Fish and Conservation Biology, Davis, California2 Dept. of Environmental Science & Policy, Davis, California3 Tanzania Wildlife Research Institute, Arusha, Tanzania
ABSTRACT- Fully protected areas such as national parks are often assumed to be the best way to conserve plant diversity and maintain intact forest composition and structure. To evaluate this, we sampled trees in areas with four different levels of protection: a national park, where the protection level is very high, a game controlled area which allows tourist hunting of big game animals, a forest reserve which allows selective harvest of trees, and an open area where human populations have unrestricted access to forest resources. All four land management areas had healthy size-class distributions with greater numbers of juvenile trees (2-10cm DBH) than adults. Mean stem density of trees was highest (947 stems ha1) in the game controlled area and was lowest (635 stems ha1) in the national park. The former had the highest basal area value (24 m2 ha1) while the human-inhabited open area had the lowest (11 m2 ha1). Species richness in the forest reserve and game controlled area was significantly higher than in the other areas. The total number of plots with unique species not found anywhere else was highest in the open area while the national park had significantly fewer plots containing unique species. Our measures of forest structure and composition show that fully protected national parks do not necessarily conserve the greatest diversity of tree species or unique species, indicating that a suite of different types of protection strategies may be the key to conservation of trees in these African dry tropical forests.
Key words: miombo ecoregion, Katavi National park, protection gradient, game controlled area
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