Economic assessment of selected regulatory ecosystem services (RES) in the Elgeyo and Nyambene Watersheds Ecosystems in Kenya

Abstract There is evidence of increased valuation of ecosystem services (ES) globally, however most of these studies tend to focus on marketed subsets of ES at national and international levels. Ecosystems differ in spatial scale, biophysical and ecological structure and functionality. This requires conducting studies at the local level to understand how, for example, the watershed ecosystem contributes to humanity both locally and nationally. This study focuses on selected regulatory ecosystem services (RES) in two catchment area ecosystems (Elgeyo and Nyambene) in Kenya. Both field-based sampling and Landsat imagery with secondary information were used to generate biophysical and ecological data. Market price-based, cost-based and unit transfer methods were used for the valuation. Aggregated economic values ​​for the selected RES were estimated at KES 37.4 billion (US$349.6 million) and KES 14 billion (US$131.3 million) for Elgeyo and Nyambene respectively. This equates to KES 1.5 million (US$13,848.48) and KES 2.6 million (US$24,187.44) per hectare per year. At the national level, the value of regulatory ecosystem services would range from US$16.6 billion to US$29.03 billion. This equates to between 15% and 26% of Kenya’s GDP in 2021, underscoring the importance of watersheds to the national economy.