Assessment of climate change vulnerability in kakamega - nandi forest ecosystem complex in Kenya

Abstract

Climate change is a global threat to the economy and human existence. Developing countries are the most threatened due to their overdependence on climate sensitive economic activities such as agriculture. In Kenya, agriculture is the mainstay of the country‘s economy yet it is highly vulnerable to the impacts of climate change. Forests play a vital role in maintaining stable climatic conditions. The central hypothesis of this study is that conversion of forests to agriculture decreases soil carbon stocks which may lead to an influx of carbon dioxide in the atmosphere ultimately increasing vulnerability to climate change. The main objective of this study was to develop climate change vulnerability indices for Kakamega - Nandi forest ecosystem complex in Kenya. Specifically, the study (i) assessed the awareness of climate change among the residents of Kakamega-Nandi forest ecosystem Complex; (ii) analyzed the effects of land-use/land-cover changes on the dynamics of soil chemical parameters and (iii) to developed Climate Change Vulnerability Indices which can be applied to predict climate change hot spots within the Kakamega - Nandi forest ecosystem complex. Cross sectional research design was used to administer 280 structured questionnaires to obtain information on climate change awareness among the residents of Kakamega - Nandi forest ecosystem complex. Land-use / land-cover changes were determined using a series of multispectral Landsat images and classified using unsupervised classification. Soil samples were randomly collected using a soil auger from 0-30 cm depth in plots of 50 m x 50 m laid in every Land-use / land-cover and mixed thoroughly in a bucket to form 102 composite samples that were kept in khaki papers and transported to the laboratory for analysis of soil organic carbon, total nitrogen, available phosphorus, potassium and Calcium using standard protocols. Descriptive analysis, Chi square and factor analysis were performed using Statistical Package for Social Sciences version 20 and effects of Land Use – Land Cover changes on soil chemical properties of soil in KNFEC was analysed using One way Analysis of Variance at significant level of P<0.05 using SAS version 9.4. The results showed that residents of Kakamega - Nandi forest ecosystem complex were aware of climate change with 24.4% and 75.6% of the respondents having little and moderate information about climate change, respectively. Changes in Land-use / land-cover showed an increase in the acreage of small-scale agriculture between 1985 and 2015. Bush land decreased by 92% between 1985 and 2015. The acreage of natural forests remained relatively constant throughout the years. There was a significant decrease in soil organic carbon in land under maize, grazing and sugarcane (P values: 0.003; 0.001 and 0.000 respectively). There was, however, a significant increase of 0.585 in soil organic carbon in regenerated exotic forest plantations. In maize plantations, total nitrogen increased significantly (p = 0.019), while in grazing, sugarcane and regenerated forest, there was a significant reduction (p = 0.011) of total nitrogen was observed. A Climate Change Vulnerability Index for assessment of vulnerability to climate change was computed by aggregating land use/land changes, soil organic carbon, temperature and rainfall. The index revealed that Climate change wellbeing increased steadily with increasing vegetation cover. Bare-land had a vulnerability index of 0.96, followed by bush-land at 0.94, tea plantation at 0.92, grassland at 0.82, small scale agriculture at 0.80, regenerated forest at 0.7 and finally natural forest at 0.38. In conclusion, conversion of natural forests to other Land-use / land-cover (agriculture) increases vulnerability to climate change. Land-use/ land-cover without meaningful forest cover such as bare land, subsistence agriculture, bush land and grassland are highly vulnerable to climate change. The results obtained will inform the policy makers and stakeholders on prioritizing and formulating mitigation approaches and adaptation strategies to significantly minimize climate change vulnerability.