Browsing by Author "Kimuyu, Duncan, M."

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Effect of fire on habitat functional diversity and herbivore diversity in Ol Pejeta Conservancy, Kenya
(2012-08) Kimuyu, Duncan, M.; Mureu, Lucy, K.; Awiti, Alex; Wahungu, Geoffrey
Background/Question/Methods The African savanna biome supports a higher diversity of herbivore species than is found in any other biome or continent. In order to maintain the habitats necessary to support a large diversity of wildlife species, much emphasis has traditionally been placed on the role of fire as a management tool. We hypothesize that herbivore abundance, diversity, and habitat utilization patterns in Ol Pajeta Conservancy in Kenya are modulated through fire management and its effect on habitat functional diversity. Between 2005 and 2010, transect surveys were used to monitor patterns of wildlife abundance and species diversity across a functional diversity gradient; from pure grassland to pure bushland. Results/Conclusions Preliminary findings show that large herbivore (black rhino, elephant and giraffe) populations increase under bushland conditions. Conversely, small grazer abundance and diversity increased in open grassland but declined markedly in Euclea divinorun and Acacia drepanolobium dominated bushland. Intense fires shift vegetation from bushland to grassland state. Low fire frequency in turn allows resurgence of bushland and decline in both abundance and species diversity of small grazers. The effect of fire on the functional diversity of habitat within savanna ecosystems has a strong influence on herbivore diversity, distributed across body size classes and feeding guild (browsers/grazers). By explicitly characterizing the effects of habitat functional diversity on herbivore species abundance and diversity, our study underscores the need for promoting biodiversity as a goal of management and conservation of wildlife in the African savannas.
Encroachment of open grasslands and Acacia drepanolobium Harms ex B.Y.Sjöstedt habitats by Euclea divinorum Hiern in Ol Pejeta Conservancy, Kenya
(African Journal of Ecology , Wiley online Library, 2013-03) Wahungu, Geoffrey M.; Gichohi, Nathan, W.; Onyangi, Irene, A.; Mureu, Lucy, K.; Kamaru, Douglas; Mutisya, Samuel; Mulama, Martin; Makau, Joseph, K.; Kimuyu, Duncan, M.
Euclea divinorum, a fast establishing, unpalatable, and fire resistant bush is considered an invasive species in some parts of its range. In Ol Pejeta Conservancy (OPC), Kenya, E. divinorum bushes cover ˜27% of the total area (˜9470 ha.) and has been expanding in coverage and encroaching into A. drepanolobium woodlands, a key woody habitat for the endangered black rhino. Between 2006 and 2010, we assessed the spatial distribution, annual rates of spread and recruitment of E. divinorum in OPC. We used data from satellite imagery and belt transects laid at the transition between E. divinorum habitat and other habitats. Density of E. divinorum seedlings increased by 27% annually over five years, with more seedlings establishing in grassland habitat (56.6%) than in A. drepanolobium woodland (43.4%). Within the infection frontier, the number of seedlings was high at the ecotone and reduced predictably with an increase in distance into the infection zone. Increase in rainfall facilitated recruitment and survival of E. divinorum seedlings and also reduced damage on trees and seedlings by mega-herbivores, especially elephants. This study confirms the encroachment of E. divinorum bushland into other habitats. This has been accelerated by burning and damage to A. drepanolobium habitat thus opening it up to encroachment by E. divinorum.