Ecosystem Services of Palmiet Wetlands: The Role of Ecosystem Composition and Function

Date: 7 November 2017

Venue: Campus Middelheim, A.143 - Middelheimlaan 1 - 2020 Antwerpen (route: UAntwerpen, Campus Middelheim)

Time: 4:30 PM

Organization / co-organization: Department of Biology

PhD candidate: Alanna Jane REBELO

Principal investigator: Patrick Meire, Karen Esler

Short description: PhD defence Alanna Jane REBELO - Faculty of Science, Department of Biology


Ecosystems are the critical infrastructure that provides society with multiple essential services. A change from one land-use to another (e.g. wetlands to agriculture) may result in trade-offs, or synergies, between different ecosystem services. As land globally becomes increasingly limited, there is greater emphasis being placed on whether ecosystems are being used optimally, in terms of their potential to provide services. Therefore a strong theoretical and empirical understanding of how ecosystems are structured, how they function and how this links to the delivery of ecosystem services is crucial in order to optimize benefits to society. Of all ecosystems, wetlands are considered to be one of the richest in terms of services provided, yet the complexity of wetland ecology has resulted in them being the least studied. South African wetlands are not well understood and many of these wetlands are in decline.

This dissertation focusses on palmiet wetlands in the Cape Floristic Region of South Africa and has four main aims: (1) to research scientifically sound measures to quantify ecosystem services (Chapter 2), (2) to map the current and historical spatial distribution of palmiet wetlands in South Africa (Chapter 3), (3) to learn about how these wetlands function to bring about the provision of ecosystem services by investigating the link between these ecosystem services, ecosystem functioning and functional diversity of wetlands at a landscape scale (Chapters 4, 5, 6, 8, 9), and (4) to test whether wetland functional groups are spectrally distinct, which may have useful applications for hyperspectral mapping of wetland ecosystem services (Chapter 7).

The main findings can be summarised in seven points. (1) Ecosystem services are not yet being adequately quantified (Chapter 2). (2) Palmiet wetlands have decreased by 31% since the 1940’s (Chapter 3). (3) Channel erosion in palmiet wetlands has caused a change 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 some extent (Chapter 5). (5) Abiotic variables and various community weighted means were key 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 of palmiet wetlands, making a case for their conservation and restoration.