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University of Nairobi (2008)

Wetlands characterization ; use by local communities and role in supporting biodiversity in the semiarid Ijara district, Kenya

Gabho, Abdullahi A

Titre : Wetlands characterization ; use by local communities and role in supporting biodiversity in the semiarid Ijara district, Kenya

Auteur : Gabho, Abdullahi A

Université de soutenance : University of Nairobi

Grade : Master of Science in Biology of Conservation 2008

This study was carried out in the semi-arid Ijara district, north eastern Kenya, whose wetlands form critical dry-season range for a diverse wildlife community, as well as livestock and humans. The aim of the project was to provide essential information for conservation and sustainable use of wetlands in the semiarid district. The specific objectives were : to determine the distribution and physical characteristics of wetlands in the study area ; to establish plant and avian community structures ofthe regularly inundated wetlands ; to determine the patterns of wetland use by people, livestock and wildlife and to evaluate the threats to wetlands and recommend appropriate conservation measures. In this study, the current status of the wetlands in terms of emergent macrophytes and avian communities were examined across three major vegetation types, which were used as the blocking factor. The blocks were : Tana riverine floodplain (Block A), Savanna woodland (Block B) and the Boni forest wetland system (Block C). Wetlands which were used by people, livestock and wildlife, and which were permanent were identified. Three such wetland sites were chosen from each block for the study. Physical inventory and mapping was done using GPS and Arc GIS techniques. 5x5 m sampling plots were used in each selected wetland to estimate herbaceous species density, richness and diversity during the dry season. Birds were counted following the area species search protocol and dry and wet season density, richness and diversitycompared. Whole 40 x 40 m plots were placed around s-e-l-ected study wetlands to indirectly , estimate wildlife and livestock utilization and preferenee using dung counts. A total of 63 community members were interviewed to determine their perceptions and use of wetlands, their functions and threats. Wetlands in the semi-arid Ijara district are diverse in type, size, distribution, hydroperiod as well as frequency of inundation.Wetlands cover over 3% of the 11,332 km2 total land area and are not uniformly distributed within the district with each study block exhibiting characteristic wetlands different from others and provide many important functions and uses.The mean herbaceous plant density among blocks ranged between 9.92±4.42/m2 and 16.15±4.911m2 estimated in the Savanna woodland and the Tana riverine blocks respectively. The highest herbaceous plant diversity (H’) was realized in Tana riverine block (1.055) followed by Boni forest (0.938) while the lowest was in the Savanna woodland (0.876) wetlands. A total of 76 different species of birds from 34 families were recorded in the studied wetlands. Bird density ranged between 2/ha and 29/ha and between 2/ha and 14/ha in the dry and wet seasons respectively. The bird species diversity among blocks for the dry and wet seasons ranged between H’ = 0.904±0.153 and H’ = 1.187±0.291 and between H’ = 0.812 ± 0.038 and H’ = 1.043±0.048 estimated in the Savanna woodland blocks and Tana riverine respectively. Wildlife dung pile abundance was significantly but negatively correlated (Spearman r = -0.824, P < 0.01) with livestock dung pile abundance. A total of 25 different wildlife species were recorded through observations and the dung pile analysis during the study period.The study revealed that dry-land wetlands in north eastern Kenya are important to the biodiversity of the region as well as its human inhabitants. However, the loss of vegetation cover due to overgrazing around wetlands in the savanna habitat puts a lot of pressure on wetlands and biodiversity, in general, condition exacerbated by the limited livestock movement in the district. There is, therefore, need for integrated management of wetlands as an integral part of the land use planning, pasture and water conservation


Page publiée le 19 décembre 2014, mise à jour le 23 février 2018