Ecosystem services of palmiet wetlands : the role of ecosystem composition and function

[摘要] ENGLISH ABSTRACT: Ecosystems are the critical infrastructure that provides society with multiple essentialservices. A change from one land-use to another (e.g. wetlands to agriculture) may resultin trade-offs, or synergies, between different ecosystem services. As land globallybecomes increasingly limited, there is greater emphasis being placed on whetherecosystems are being used optimally, in terms of their potential to provide services.Therefore a strong theoretical and empirical understanding of how ecosystems arestructured, how they function and how this links to the delivery of ecosystem services iscrucial in order to optimize benefits to society. Of all ecosystems, wetlands areconsidered to be one of the richest in terms of services provided, yet the complexity ofwetland ecology has resulted in them being the least studied. South African wetlands arenot well understood and many of these wetlands are in decline.This dissertation focusses on palmiet wetlands in the Cape Floristic Region of SouthAfrica and has four main aims: (1) to research scientifically sound measures to quantifyecosystem services (Chapter 2), (2) to map the current and historical spatial distributionof palmiet wetlands in South Africa (Chapter 3), (3) to learn about how these wetlandsfunction to bring about the provision of ecosystem services by investigating the linkbetween these ecosystem services, ecosystem functioning and functional diversity ofwetlands at a landscape scale (Chapters 4, 5, 6, 8, 9), and (4) to test whether wetlandfunctional groups are spectrally distinct, which may have useful applications forhyperspectral mapping of wetland ecosystem services (Chapter 7).The main findings can be summarised in seven points. (1) Ecosystem services are notyet being adequately quantified (Chapter 2). (2) Palmiet wetlands have decreased by31% since the 1940's (Chapter 3). (3) Channel erosion in palmiet wetlands has caused achange in water and soil quality and a shift in plant communities (Chapter 4). (4)Relative groundwater depth and soil pH explain patchiness in palmiet wetlands to someextent (Chapter 5). (5) Abiotic variables and various community weighted means werekey in underpinning wetland ecosystem properties in palmiet wetlands (Chapter 6). (6)Functional groups, and even species, in palmiet wetlands appear to be spectrally distinct(Chapter 7). (7) Palmiet wetlands provide valuable ecosystem services to society,particularly the sequestration of carbon, water purification and flood attenuation(Chapters 8, 9). In conclusion, these findings highlight the uniqueness and value ofpalmiet wetlands, making a case for their conservation and restoration.

[发布机构] Stellenbosch University