Quantifying ecosystem service supply-demand relationship and its link with smallholder farmers’ well-being in contrasting agro-ecological zones of the East African Rift

Abstract

Ecosystem service supply (ESS) has experienced a progressive decline due to degradation and increased ecosystem social demands (ESD). Quantitative studies assessing ecosystem services have mostly focused on ESS with limited attention to ESD and human well-being. To quantify, analyze and map the ESS, ESD, ESDR (Ecosystem Supply-Demand Ratio), weight-based smallholder farmers’ well-being (SWB), subjective satisfaction and change-driving factors, questionnaire surveys, semi-structured interviews and focus group discussions were used in contrasting agro-ecological zone (AEZ). The soil loss rate was estimated and mapped using the Revised Universal Soil Loss Equation (RUSLE) to evaluate the role of soil erosion control in regulating ESS. A five point Likert scale was employed to evaluate smallholder farmers’ well-being (SWB), subjective satisfaction, and the contribution of ESS to the components of well-being. A radar diagram was used to link ESS, ESD and SWB. The research was carried out between October 1, 2019 and March 30, 2020. The results showed a high supply of provisioning ESS observed in the humid AEZ, whereas low provisioning ESS was observed in the semi-arid AEZ. The observed ESS was not in accordance with ESD, and different change drivers affecting this balance were identified by smallholder farmers. Population pressure was identified as the main driver from smallholder farmers’ report and was confirmed by the multiple linear regression model. Due to the undulating topography, a high rate of soil loss was observed in the humid AEZ. Smallholder farmers in humid AEZ attached higher values for soil erosion control than those from the semi-arid AEZ. Of all indicators of SWB, income was assigned the highest weight while receiving low subjective well-being satisfaction levels in both humid and semi-arid AEZs. The overall relative contribution of ESS shows a medium relationship with all components of smallholder farmers’ well-being. Therefore, we suggest policies and strategies that would help to recuperate, and the continuous flow of ESS, control population growth, and improve well-being.