Relationship Between Frequency of Ecological Disturbances and Invasive Plant Species Diversity in Kakamega Forest, Kakamega County, Kenya
Abstract
Ecological disturbances are key drivers of biodiversity change in tropical forests, often facilitating the spread of invasive plant species. Global evidence from the Amazon, Congo Basin, and Southeast Asia shows that logging and resource extraction disrupt forest structures and ecological balances. Similarly, East African forests such as Budongo, Mau, and Mabira have experienced degradation, leading to reduced native biodiversity. Kakamega Forest, Kenya’s only remnant of the Guineo-Congolian rainforest, faces growing anthropogenic pressures, yet the specific influence of ecological disturbances on invasive plant species diversity remains underexplored. This study investigated how the frequency of selected ecological disturbances livestock grazing, animal wallowing, fuel wood collection, and beekeeping, contributes to invasive plant species diversity in Kakamega Forest. Employing a cross-sectional research design that incorporated both quantitative and qualitative data, the study sampled 60 plots (10 m × 50 m each) across stratified disturbance levels (highly disturbed, moderately disturbed, and undisturbed) using systematic random sampling. Data collection involved GPS mapping, field observations, species identification, frequency counts, Likert scale assessments, and informal interviews to contextualise local practices. Quantitative analyses included Spearman’s rank correlation to assess bivariate relationships and multiple regression analysis to evaluate the combined predictive strength of disturbances. The results revealed that grazing frequency had a significant negative correlation with invasive plant species diversity (ρ = –0.500, p < 0.01), likely due to trampling and selective foraging. Animal wallowing sites showed a weak positive correlation (ρ = 0.274, p < 0.05) with invasive diversity, linked to localised soil disturbance. Beekeeping areas recorded the lowest invasive diversity (mean = 1.17), supporting their promotion as low-impact livelihoods, while fuel-wood collection areas had the highest (mean =2.33), reflecting microhabitat alterations. Overall, ecological disturbances accounted for 25.5% of the variation in invasive plant species diversity (R² = 0.255), leaving 74.5% unexplained, highlighting the influence of additional ecological factors. The study concludes that disturbance frequency significantly shapes invasive diversity in Kakamega Forest. It recommends zoning based on disturbance intensity, encouraging low-impact activities such as beekeeping, and adopting a Disturbance Impact Monitoring Framework (DIMF) to guide sustainable management. Future research should examine climatic variability, soil properties, seasonal dynamics, and seed dispersal mechanisms to build more robust predictive models, ensuring the long-term conservation of this critical forest ecosystem.
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