Cumulative effects of policy and management actions on ecosystem services. Challenges and methodological approaches in The Future Okavango project

The Okavango Basin encompasses a wide range of ecosystems and, corresponding to its extension across Angola, Botswana and Namibia, a multitude of communities with diverse socio-economic contexts, that in turn are determined both, by local traditions and regional and national policies. With the river acting as a connecting element, managing the use of natural resources under consideration of conservation issues is a challenging task. The interdisciplinary research project "The Future Okavango" (TFO) aims at contributing to integrated, sustainable land management by providing scientific support to stakeholders from local to national levels. The region under investigation, a system of woodlands, floodplains and extended wetlands is of crucial global importance for biological diversity. Simultaneously it is threatened by rapid transformation through climate change, population growth and anthropogenic over-utilization of natural resources, which may amplify land and water conflicts. The project adopts an approach of mapping and valorising a set of representative ecosystem services and the underlying ecosystem functions. Since these are provided at different spatial and temporal scales, and can show varying properties at different scales, a multi-scale approach is required that covers services from the plot-scale to the full Okavango Basin area. Besides the issue of multi-scale variation, cumulative effects may occur between different processes in both, the spatial and temporal dimension, and causing off-site effects or services being partially determined by past processes. In this paper we identify key issues in the assessment process in a wider conceptual context and describe mapping and assessment procedures. Finally, we introduce the concepts utilized to integrate sectorial assessments of ecosystem services and provide an example of an integrated assessment for a theoretical case study in Northern Namibia