Department of Environmental Studies

Permanent URI for this collectionhttps://repository.chuka.ac.ke/handle/123456789/149

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Browsing Department of Environmental Studies by Subject "Anthropogenic disturbances"

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    Impact of selected anthropogenic disturbances on the temporal variability of riparian vegetation in the river Kathita basin, Tharaka Nithi county, kenya
    (Chuka University, 2024) Mugambi Denis Kibaara
    Riparian areas play a significant role in provision of environmental goods and services and are hotspots for biodiversity. These fragile ecosystems however are increasingly threatened by human activities such as sand harvesting, charcoal burning and livestock grazing which alter their structure and composition. This study investigated the impact of the selected anthropogenic disturbances specifically; sand harvesting, charcoal burning and livestock drinking bays on the riparian vegetation variability of River Kathita, Tharaka sub-catchment area, Kenya. The study employed satellite imagery analysis using Normalized Difference Vegetation Index (NDVI) from 2003 to 2023. The results revealed a decline in vegetation health, with NDVI values dropping from a mean of 0.41 to 0.32 over the 20 years. Land use and land cover analysis indicated a decline of 30% forest area and an increase of 466.7% in development area. Sites affected by sand harvesting, charcoal burning and livestock grazing exhibited lower species diversity (0≥H<1.5) while undisturbed sites maintained higher diversity (1.1>H ≤2). Although Kruskall-Wallis test for tree diversity among the sites was not statically significant (p=0.07), results for tree species richness were (p=0.047). Charcoal burning sites were characterized by large tree diameters at breast height (DBH) but lower tree heights. Sand harvesting and charcoal burning sites had high diversity of seedlings and saplings in abandoned sites indicating ability to recover and re-establishment of vegetation in absence of disturbance and with protection. Livestock drinking bays showed a shift in vegetation composition from grasses and shrubs to dominance by forbs and herbaceous plants. There were strong correlations between sand harvesting, charcoal burning, livestock grazing and tree diversity which was significant for livestock grazing (p=0.01) and marginally insignificant for sand harvesting and charcoal burning (p=0.06). The study recommends local and national stakeholders regulate sand harvesting, charcoal production in riparian areas and develop strategies for managing livestock access to drinking bays. Future research should explore the combined effects of climate change, agriculture and land-use policies on riparian habitats ecosystems.