PARENT SESSION
Special Session 12: Millennium Ecosystem Assessment Part I: A synthesis of core findings
Organized by: EM Bennett and H Mooney
Thursday, August 11, 8:00 AM - 11:30 AM, Exhibit Hall 210a-e, Level 2, Palais des congrès de Montréal
Case study: Multi-scale assessment of ecosystem services in southern Africa.
Biggs, Reinette*,1, Desanker, Paul2, Fabricius, Christo3, Lynam, Timothy4, Scholes, Robert1, van Jaarsveld, Albert5, 1 Division of Water, Environment and Forestry Technology, Pretoria, South Africa2 Department of Geography, University Park, Pennsylvania, USA3 Department of Environmental Science, Grahamstown, South Africa4 Institute of Environmental Studies, Harare, Zimbabwe5 Faculty of Science, Stellenbosch, South Africa
ABSTRACT- The Southern African Millennium Ecosystem Assessment (SAfMA) assessed the links between changes in ecosystems, the services provided by ecosystems, and the welfare of southern Africa's people. It was conducted at three loosely-nested spatial scales: the subcontinent; two major river basins (the Zambezi and Gariep) within the region; and several local communities within each river basin. Four clusters of services, relating to water, food, woodfuel and biodiversity, were assessed at all scales. This allowed for cross-scale comparison, evaluation of cross-scale dependencies and assessment of trade-offs between services. It was found that the distribution of some services, for example water, is 'fractal': at successively finer scales of assessment, heterogeneity is revealed within areas that appear homogeneous at slightly larger scales. Other services, such as woodfuel, are based on ecological and human processes that have a fairly well defined scale domain. Provided the observations and models are made with a resolution sufficient to capture these processes, the extent of the assessment is not crucial to the outcome. Biodiversity, which is notoriously scale-dependent, was assessed by means of a new abundance-based, scale-insensitive indicator that was developed for the study. Cross-scale dependencies in, for example, water policy were highlighted by the assessment: given that all major river basins in the water-scarce southern part of the region are shared between two or more countries, ensuring adequate water supplies at the local scale is partly dependent on international cooperation. There is seldom a single optimum scale for ecosystem assessment. Adopting an integrated multi-scale and multi-service approach provided insights that would otherwise have been missed. An adequate understanding calls for assessment at a small number of carefully selected and delimited scales, which interact with one another. This is more challenging and costly than a single-scale or single-sector assessment, but is compensated by the increased impact achieved. It is much easier to engage stakeholders at scales that are meaningful to them, and the stakeholders play an important role in defining the key issues at the different scales.
Key words: Southern Africa, multi-scale, assessment, ecosystem services