Masters Degrees (Conservation Ecology and Entomology)

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Browsing Masters Degrees (Conservation Ecology and Entomology) by Author "Briggs, Andrew John"

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    Pond biodiversity in a sugarcane-forestry mosaic in KZN
    (Stellenbosch : Stellenbosch University, 2016-03) Briggs, Andrew John; Pryke, James S.; Samways, Michael J.; Conlong, D. E.; Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.
    ENGLISH ABSTRACT: The wetlands of South Africa are threatened by dam creation, agricultural practices and urbanisation. Farm ponds within these wetlands act as habitat islands and are known to support heterogeneous communities of aquatic organisms which often include rare or unique species not found in other water body types. The timber and sugarcane industries of KwaZulu-Natal (KZN) province, South Africa, are very important to the local economy and make up a large portion of the farmland in the province. Timber, and more recently, sugar farmers in KZN are farming their lands with environmental sustainability in mind. This shift towards more biodiversity friendly agriculture should have positive effects on biodiversity conservation. This study aims to assess the differences in species assemblages of three different taxonomic groups within ponds found in forestry and sugarcane agriculture, and to look at the quality of habitat within the two agricultural mosaics using bioindicators. Sites within protected areas were used as benchmark sites. In Chapter 2, I assessed the conservation value of farm ponds within timber and sugarcane plantations by gathering biodiversity data on plants, aquatic Coleoptera and Odonata. Plants were sampled using transects, aquatic Coleoptera were sampled by sweeping a net through the aquatic area along the banks of the ponds and Odonata were sampled through visual observations. No significant differences were found between the wetland groups regarding species richness of plants, aquatic Coleoptera and Odonata. Species richness of the Coleoptera was low at all sites whilst the species richness of Odonata was highest in sugarcane sites which had a large open water surface, compared to smaller sites within sugarcane and forestry agriculture. Sugarcane sites contained the most invasive alien plants based on high levels of agricultural disturbance whilst still maintaining high levels of Odonata diversity, therefore indicating the importance they possess as alternative habitat for various invertebrates. In Chapter 3, the focus was primarily on utilising the Dragonfly Biotic Index (DBI) and the presences of rare and threatened Odonata to assess the conservation significance of ponds and reservoirs in a sugarcane-forestry mosaic. In order to achieve this I used the Odonata population data that was gathered, and assigned the various species their scores which subsequently allowed me to make deductions about the habitats in which they were found. The results indicate that the protected areas in my overall study area had the highest quality habitat with more Odonata species which are sensitive to disturbance being found at these localities. Despite this finding, ponds within sugarcane agricultural mosaics were able to support many Odonata species, including some which were not found in the protected areas. However, these were predominately widespread generalists with low conservation value. In conclusion, I found that species richness was a poor indication of pond conservation value and subsequently recommend using DBI for future monitoring. Although the sugarcane farms were able to support high numbers of generalist species, these results indicate that farmers could be doing more to encourage environmentally sensitive species into their wetlands, such as restoration through alien clearing.