Local assessment of changes in water-related ecosystem services and their management: DPASER conceptual model and its application in Taita Hills, Kenya

摘要

Fresh water provisioning is a crucial ecosystem service (ES) in the agrarian societies of East Africa. Water resources are highly dependent on several other ES such as the water retention capacity of vegetation and the purification properties of soil.However, ES are constantly challenged by dynamic changes within water-land-vegetation-human relations. Environmental policies usually address immediate anthropic pressures but overlook multiple historical stressors, or 'drivers'. This article presents alocal assessment of changes in the water-related ES in the Taita Hills, Kenya, applying the Drivers, Pressures, Actions, State, Ecosystem services, Responses (DPASER) model, adapted from the Drivers, Pressures, State, Impacts, Responses (DPSIR) framework, boosted with ecosystem services and human actions and combined into a historical perspective. A review of the legislation, interviews, participatory mapping, timelines and focus group discussions were used in data gathering. The results indicate thatland demarcation in the 1960s and consequent land privatization have been the main drivers of change in water-related ES, since these determined the prioritization of agricultural production over conservation of forests, wetlands and rivers. This case study shows that the degradation of water-related ES is strongly linked to historical development of land ownership and loss of commonality, and suggests enhancement of inter-sectoral management.