Land use changes and their effects on Mt Elgon forest ecosystem, Kenya

Abstract

Mt. Elgon forest ecosystem provides the forest adjacent communities with varied ecosystem services. Consequently, changes in land uses in Mt. Elgon forest ecosystem could lead to a decline in biodiversity and the livelihoods of the forest-adjacent communities. This study assessed land use changes and their effects on biodiversity and livelihoods in the Mt. Elgon forest ecosystem. The study used systems theory to demonstrate the complexity of the interrelationships of variables. Quantitative research approaches were used whereby used in collecting data on floral diversity and by use of questionnaires. Landsat imageries were used to assess land use changes between 1977 and 2019. Drivers of land use changes were determined using questionnaires administered to three hundred and eighty-seven (387) respondents that were purposively sampled from Mt. Elgon forest ecosystem. Effects of land use changes on floral diversity were evaluated using 50m x 50m duplicate quadrats that were placed in different land uses. Impacts of land use change on the forest-adjacent communities livelihoods was determined using questionnaires, Key Informants and Focus Group Discussion. Data collected from satellite imageries were analyzed by applying supervised classification using Arc GIS 10.5. The Shannon-Weiner diversity index and Whittaker beta diversity index was used to determine changes and similarities in floral diversity, while Kruskal Wallis test and chi square test was used to determine differences in species abundances. Questionnaires were analyzed using Statistical Package for Social Sciences (SPSS). Results established that there has been an 18% decline in the natural forests between 1977 and 2019. A similar decline of 15.19% was recorded in bamboo forest. Plantation forests established in the 1990s, have also experienced a 16% decline between in 1999 and 2019. There was a 29% increase in mixed farming, and a 0.13% increase in tea farms. Increase in population was reported by 76.7% of the respondents as the major driver of land use changes. Ninety-one (91) percent of the respondents obtained their livelihoods from the forest and the decreasing natural forest area has negatively impacted livelihoods of the forest-adjacent communities with herbal medicine experiencing the highest decline of 28% followed by timber and fodder. This study established that there were differences in floral diversity in relations to land use changes. The Shannon-Weiner diversity index revealed that control (natural forest) site had the highest species diversity (H=2.07331, evenness=0.884), followed by indigenous plantations (H=1.93962; evenness 0.69957), urban settlements (H=1.85081; E=0.66754), Nyayo Tea Zone (H=1.5324, E=0.56), mixed farming (H=1.43694, E=0.43694) and exotic plantation (H=1.28231, E=0.61612). Whittaker beta diversity index for control site verses urban settlements was (0.5385), indigenous plantations (0.2222), Nyayo Tea Zone (0.1429) while mixed farming and exotic plantations (0.000). Kruskal-Wallis test revealed a statistically significant differences in total number of plant species in the various study sites (H=8.288; P=0.049). Similarly, the results revealed a significant difference between specific plant communities in the study area (H=38.116; P=0.000). Chi square test revealed that the difference in distribution of species communities in different location were insignificant. Results of species diversity analysis show that land use changes may be responsible for changes in floral diversity. There were insignificant differences in the species diversity between the control and indigenous forest suggesting that such a change can restore floral diversity on a proximal time scale. Changes in land uses to NTZ and exotic plantations have led to an increase in herbs and a decline in tree species. Land use changes have significantly impacted floral diversity and livelihoods of Mt. Elgon forest-adjacent communities. The study recommends the use of mixed indigenous plantations to restore floral diversity of Mt. Elgon forest ecosystem