- Title
- Roads and their effects in fynbos of the south-eastern Cape: implications for conservation and management of road verge vegetation
- Creator
- Grobler, Barend Adriaan
- Subject
- Plant ecology -- South Africa
- Subject
- Ecology -- South Africa Ecology -- Research -- South Africa Conservation biology -- South Africa
- Date Issued
- 2018
- Date
- 2018
- Type
- Thesis
- Type
- Doctoral
- Type
- DPhil
- Identifier
- http://hdl.handle.net/10948/30105
- Identifier
- vital:30825
- Description
- Roads are some of the most conspicuous and pervasive conduits of human influence in modern landscapes. Over the past three decades, there has been a growing interest in the ecological effects of roads. These effects are numerous and generally deleterious, but much of our current knowledge on the matter stems from research conducted in North America, Britain, and Europe, where the focus has been on animal components of ecosystems. There is, however, a need for a plant dimension in road ecology, especially in those areas where plant biodiversity, and threats to this biodiversity, are concentrated. The research presented in this thesis aimed to further our understanding of road effects on the plant component of fynbos ecosystems in the megadiverse Cape Floristic Region (CFR). The exceptional plant diversity of the Cape and the presence of an extensive road network in the region present an ideal system for studying the interactions of roads and plants. Road verges have been emphasised as valuable habitats for plants. However, to assess the viability of road verges as habitats for fynbos plants, we first need to understand how these communities are influenced by the disturbances that exist in these environments. To this end, I investigated fynbos plant communities along roads and showed that road-mediated changes in the soil environment can bring about subtle changes in their composition while key components of the communities persist in road verges. Even though fynbos community patterns remain intact in road verges, the ecological processes that facilitate the persistence of plant species may be disrupted in these environments. As such, I studied the pollination of an ornithophilous plant in road verges and fynbos fragments of a highly transformed landscape. Here, landscape context was an important determining factor in the visitation rate of birds to plants in verges, with those occurring next to transformed land experiencing reduced visitation rates. Furthermore, I studied the pollination and fecundity of a highly threatened entomophilous plant and showed that, while there were no impacts on reproductive output of plants, road effects bolstered the reproductive growth of plants near the road. ii Finally, I implement the road-effect distances identified in the above studies to estimate the proportion of extant fynbos vegetation that may be impacted by roads. While the proportion of vegetation affected by roads is small, a substantial proportion is in close proximity to roads, potentially rendering large areas vulnerable to road-mediated human impacts. I further highlight the fact that several plant species of conservation concern in the Cape are affected by roads, and that many of these constitute a significant proportion of South Africa’s threatened flora. A case study from the N2 national road in the south-eastern Cape, where vegetation in road verges is in a better condition than that of adjacent, demonstrates the potential conservation value of road verges for fynbos vegetation in the region.
- Format
- vi, 158 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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