Urban and Peri-urban Agroforestry (Upaf) for Climate Change Adaptation and Ecosystem Services Provision in Kiambu Sub-county, Kenya

Abstract

Although they occupy less than 2% of the earth's surface, urban and peri-urban areas utilize 78% of the world's energy and generate more than 60% of the greenhouse gas emissions. The urgency for climate change mitigation and adaptation strategies is underscored by the impact already being felt in cities due to rising temperatures extreme weather occurrences such, as floods and droughts and the proliferation of tropical diseases. Therefore, this study aimed to evaluate how climate change and variability has changed from 1990 to 2022 in Kiambu Sub-County; to find out how land use in Kiambu Sub-County has changed from rural to urban from 1990 to the present; and to determine how best urban and peri-urban agroforestry can support climate change adaptation and ecosystem service provision in the study area. The research employed a descriptive survey design to gather data. Secondary research methods were utilized to collect climate data (rainfall and temperature) from the Kenya Meteorological Department. Maps and satellite imagery were employed to assess the changes in land use and land cover in Kiambu. Additionally, key informant interviews, household interviews, questionnaires, on-farm observations, and transect walks were conducted to assess the role that peri-urban and urban agroforestry play in ecosystem restoration and climate change adaptation. After undergoing analysis using both descriptive and quantitative methods, the data was presented textually as well as through time series graphs, line graphs, charts, and tables. The assessment of climate change and variability in Kiambu County from 1990 to 2022 revealed statistically insignificant trends in annual rainfall, with Sen’s Slope indicating a marginal increase of 3.09 mm/year (p-value: 0.57), highlighting high inter-annual variability with no clear direction. In contrast, temperature analysis showed a significant upward trend, with Sen’s Slope values of 0.02°C per year for maximum temperatures and 0.044°C for minimum temperatures. Land use in Kiambu sub-county was found to have drastically shifted, with urbanization increasing Urban Built-up areas by 119% and Cultivated Built-up areas by 25% from 1990 to 2022, while woodland and cultivated land decreased by 37% and 23%, respectively, due to rapid population growth and urban sprawl. This trend reflects intensified competition for land resources, impacting water availability and ecological stability. Agroforestry emerged as a key climate adaptation strategy, promoting resilience through compact systems such as balcony gardens, multi-storey cropping, and the cultivation of climate-resilient crops. Agrisilviculture and agrisilvopastoral, emerged as prevalent and valuable agroforestry systems. These practices and systems were found to provide various ecosystem services, including shade, improved air and water quality, and the production of essential resources such as food, timber, fruits, building materials, and wood fuel and contribute overall towards Climate Change Adaptation. The tree species diversity, with a Shannon index of 3.1487, reflected the enhanced ecosystem resilience as a result of agroforestry practices adoption in Kiambu sub-county. However, Despite recognized ecosystem services, challenges like limited seedling access and market availability hinder widespread agroforestry adoption. Recommendations therefore emphasized sustainable urban planning, gender-inclusive interventions, educational programs for sustainable Urban and Peri-Urban agroforestry, and policy alignment across sectors for climate resilient communities