Effects of vegetation disturbance on small mammals diversity and distribution in Oloolua forest, Kenya

Abstract

ThIs thesis describes investigations carried out from October 2008 to March 2009 to asses the effects of vegetation disturbance on diversity and distribution of small mammals in Oloolua forest, Kenya. Four different forest habitats with various anthropic interference levels were assessed for vegetation and small mammals. Small mammals were sampled by trapping on square grids with 16 live traps, set out in a plot of 25m x 25m plot in every habitat. Overall, 67 woody species and 79 species of herbs were recorded in Oloolua forest. There was significant difference in woody species density among habitats (F3.204= 2.78, P <0.05) in the forest. Similarly, there was significant difference in herbs density among habitats (F3,420= 18.97, P <0.05) in the forest. Diversity index of woody plants was highest in the natural forest (2.7), followed by woodlands (2.5) and the eucalyptus plantation forest (1.9). Nine species of small mammals were recorded in the forest and they represented four main orders: Rodentia, Erinacemorpha, Primates and Carnivora. The Giant rat (Cricetomys gambianusy was most abundant species in the entire forest, while the hedgehog (A.albiventris) and cane rat (T.swindderianus) recorded the lowest numbers. Diversity index of small mammals was highest in the woodland (0.6), followed by the natural forest (0.35) and these two habitats provided greater diversity of small mammals than disturbed habitats. Giant rat (c. gambianus) and Tree squireel (P. ochraceus) were found to prefer areas with high plant cover and diversity while slender mongoose (H sanguineus) and white tailed mongoose (I albicauda) were dominant in open woodland habitat. This study has shown that there is lower small mammal species richness in disturbed habitats compared with undisturbed habitats. Finally, this study recommends further studies to quantatively assess specific responses of each species of small mammal to quarrying and plantations. The conservation of the forest will be key to future survival of the species and enhanced ecosystem functioning.