Browsing by Author "Kennedy, Kristen"
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- ItemOpen AccessFynbos connectivity as a function of dispersal distance and the implications for bird conservation in the greater Cape Town area(2013) Kennedy, Kristen; Cumming, GraemeConnectivity is defined as the degree to which a landscape facilitates an organisms' movement. It is considered a vital element of landscape structure with key implications for metapopulation survival and ecological processes such as pollination. The connectivity of a landscape changes depending on an organisms' ability to move between patches of favourable habitat and this in turn is related to the dispersal ability of the organism. Connectivity thus changes with the scale at which the landscape is viewed; however the relationship between connectivity and dispersal ability is overlooked in many studies. This study looks at the connectivity of two types of fynbos: Highland fynbos (Thicket, Bushland, Bushclumps and High fynbos) which makes up 22.7%, and Lowland fynbos (Shrubland and Low Fynbos) which makes up 28% of the studied extent. These vegetation types are outlined by the National Land Cover Database (NLCD 2000) and analysed as a function of organism dispersal ability in the greater Cape Town area. It is shown that a relationship between dispersal ability and connectivity exists; however the relationship is not linear but sigmoidal with inflection points at 45% connectivity. This raises the question of a connectivity threshold in the Fynbos Biome. Characteristics of the landscape are assessed and it is shown that Fynbos vegetation in the greater Cape Town area is highly fragmented. Fragmentation and habitat loss decrease connectivity and are thus important factors in conservation. In order to simulate the effect of further fragmentation through habitat loss, patches of increasing size were removed and the results put into context for conservation of both the vegetation types and the dispersing organisms dependent on them. The importance of conserving patches of remnant vegetation in order to facilitate organism dispersal is highlighted by this study.
- ItemOpen AccessA socio-ecological systems approach to understanding development in a dynamic world : a case study of traditional agriculture in Pondoland, South Africa(2015) Kennedy, Kristen; Pereira, Laura; Wynberg, RachelArguably one of the greatest challenges currently facing humankind is the linking of environmental sustainability with poverty reduction and social justice. These issues all come to a head in the rural smallholder agricultural regions of "underdeveloped" Africa .In these settings climate change and food security are but two of the many challenges faced on a daily basis, compounded by the need for "development". Through a case study of smallholder farmers facing multiple contested development trajectories, this research takes a social-ecological systems approach in order to: 1. investigate the past, present and future dynamics of smallholder agriculture and food practices in mPondo communities of the Wild Coast 2. locate the role of agriculture and agri-food systems in the local development discourses 3. describe the perceived opportunities and challenges which face the local agri-food system Through semi-structured interviews, informal discussions, workshops and participant observation in three regions of the Wild Coast of the Eastern Cape a trend of rapid cultural erosion was observed. Many traditional crops are no longer cultivated as farmers turn to commercial seeds and modern cooking methods. Three dominant development trajectories are explored for one region, focusing on the AmaDiba community whose history of resisting imposed development is again being tested by contentious titanium mining proposed in nearby Xolobeni. A central finding is that while resisting imposed development in order to achieve a self-defined development which values mPondo traditions and subsistence off the land, these communities - described as possessing strong community agency - are losing the very culture they are fighting to defend. This is made clear through the social-ecological systems approach of resilience theory. In building resilience to imposed development the community has become vulnerable to other disturbances. As this traditional agri-food system continues to face the enduring shocks of global environmental and social change, the communities must recognise their fragilities as well as the threats which have been overlooked in the past. This study therefore suggests that the community exploit this stage of readjustment so as to reorganise, building on local culture and tradition, through an integrated approach to development which combines agriculture, traditional food and tourism.
- ItemOpen AccessA turbulent diatom vs dinoflagellate phytoplankton biomass model(2013) Kennedy, Kristen; Moloney, ColeenPhytoplankton blooms play an important role in global primary productivity and the dynamics of blooms are of interest to modellers. Diatom dominated phytoplankton blooms followed by dinoflagellate blooms are common in the Southern Benguela, and are often associated with Harmful Algal Blooms. A well-known ecological explanation for the succession of diatoms to dinoflagellates is given by Margalef’s Mandala which attributes the successional change to the interaction between turbulence and available nutrient concentration. This study introduced a simple variable accounting for the effects of turbulence to a numerical model describing diatom and dinoflagellate growth in order to emulate the common successional pattern. Succession was successfully modelled by reducing the maximum growth rate of diatoms in stratified conditions. The model was then used to investigate the predictions of Margalef’s Mandala. This study unpicks the relationship between nutrients, turbulence, diatoms and dinoflagellates through a simple 0D phytoplankton model with interesting insight into the role of turbulence in phytoplankton dynamics.