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Martinique became a full overseas department of France in 1946 (27:802), and Saint Lucia will soon change its status from a BritiSh colony to an independent Caribbean nation. Such political changes indicate that these small islands must rely ever increasingly upon their own resources to satisfy their needs. [...]

A vegetation survey, on the plant community level of organization, was conducted on the Mfabeni swamp on the eastern shores of Lake St Lucia. The survey included both the sedge/grass swamp and the swamp forest. Mfabeni swamp is a peatland with peat up to 10m in depth. Except for limited studies in Lesotho and KwaZulu-Natal, this is a first vegetation survey on the plant community level of peatland vegetation in southern Africa. Total floristic composition and habitat information were recorded in 214 sample plots, fully referenced by GPS for GIS mapping. The data were captured in the TURBOVEG data base for vegetation data, classified using the TWINSPAN numerical classification algorithm and phytosociological tables were compiled using the MEGATAB computerized table management program. Fourteen plant communities were identified, characterized by diagnostic and dominant species, described, and the localities noted by GIS. The data were also processed by the PCOrd numerical ordination program and the axes of the resulting ordination diagrams were related to environmental conditions. This gave an indication of the environmental factors controlling the existence and distribution patterns of the different plant communities. An ordination was run on the habitat data collected to further illustrate the relationship between the plant communities and environmental variables. It seems that water depth, seasonality of the water depth and certain water chemical properties, such as pH conductivity and dissolved oxygen content of the water play an important role in determining floristic composition and therefore plant community type in the Mfabeni swamp. / Dissertation (MSc(Botany))--University of Pretoria, 2006. / Plant Science / unrestricted

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A decision support framework (DSF) to guide watershed management planning in St. Lucia was developed. The DSF, supported by three components, integrated physiographic criteria in spatially defining sustainable land management regimes, crop suitability based on agro-ecologic zoning criteria, and water quality modelling tools. / In the first component, a methodology for agricultural and forestry land management zoning based on decision-rule frameworks was developed, employing GIS-based spatial multiple-criteria integration techniques. Land capability, recommended land management regimes, crop suitability and broad agricultural/forestry land utilization type zones were derived for the country. Sixteen broad agricultural and forestry land utilization types (LUTs) based on FAO agro-ecologic zoning guidelines were spatially defined over the island. These LUT zones represent relative suitability for rain-fed annual and perennial crop production, grazing and forestry. / In the second component, field research to quantify rainfall, runoff and erosion from two small watersheds under contrasting land management regimes was undertaken. Over the study period the erosion rate from an intensively cultivated, degraded agricultural watershed was 20 times that of a completely forested watershed. SCS curve numbers were evaluated for both watersheds based on rainfall-runoff relationships. / The third component demonstrated the application of a distributed-parameter hydrologic/water quality model, AnnAGNPS, in land management scenario evaluation, in terms of runoff and soil erosion. Data from the second component were used to calibrate and validate the model in simulation of daily runoff and erosion losses from the two watersheds over the study period. The model generally performed better in runoff simulation for the agricultural watershed compared to the forested watershed. Average annual erosion rates under current land management regimes were estimated at 73.3 and 7.2 t/ha for the agricultural and forested watersheds respectively. The model was applied to simulate runoff and erosion losses from the agricultural watershed under alternative sustainable land management regimes derived in the first component. Simulated average annual erosion losses were reduced to 9.2 t/ha. / This study demonstrated the application of efficient and powerful computer-based tools in the development of a decision support framework for watershed management planning for small islands.