• Login
    View Item 
    •   ResearchSpace Home
    • College of Agriculture, Engineering and Science
    • School of Life Sciences
    • Biological Sciences
    • Grassland and Rangeland Science
    • Masters Degrees (Grassland and Rangeland Science)
    • View Item
    •   ResearchSpace Home
    • College of Agriculture, Engineering and Science
    • School of Life Sciences
    • Biological Sciences
    • Grassland and Rangeland Science
    • Masters Degrees (Grassland and Rangeland Science)
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    The coastal grasslands of Maputaland, South Africa : effects of fire and grazing on vegetation structure, diversity, and composition.

    Thumbnail
    View/Open
    Thesis. (25.64Mb)
    Date
    2007
    Author
    Dalton, Brian Patrick Alexander.
    Metadata
    Show full item record
    Abstract
    A series of trials and investigations were implemented to address concerns surrounding the dynamics of the fire-climax wooded/edaphic grasslands within the iSimangaliso Wetland Park, northern KwaZulu-Natal, South Africa. The research problem surrounded inadequate historical evaluations of changes in vegetation structure, grasslands progressing to a woody dominated composition, and increases in Helichrysum kraussii (Curry bush). These were addressed as follows: Firstly, the recovery of vegetation in response to different periods of fire exclusion in different communities along a topographical gradient of a coastal dune area, was assessed over a two year period. Secondly, the regeneration after wildfire of the persistent, stress tolerant shrub H. kraussii, was studied on different catenal positions with differing fire exclusion periods and with and without defoliation of surrounding plant biomass in the coastal edaphic grasslands north of Manzengwenya, South Africa. Thirdly, aerial photography from 1937, 1975, and 2000 was georectified, digitised and analysed using a Geographic Information System to examine broad vegetation changes in response to different management regimes for a site on the Eastern Shores of Lake St Lucia and a site within the Tewate Wilderness Area. In the absence of fire, the coastal edaphic grasslands progressed to a closed canopied scrub forest within six years. An increase in fire exclusion period resulted in a decrease in species abundance, an increase in woody height, and a decrease in plant density. Richness increased initially but declined marginally with increased fire exclusion period. Higher lying east and west facing sites had a better veld condition index compared with bottom sites and had an increased response (vigour) to defoliation but were far more likely to succeed through to woody scrub forest. Woody plant biomass vigour was greater for west facing sites. Ordination of species composition across sites in response to fire exclusion and catenal position revealed greater similarities within exclusion periods than between. Bottom sites were more similar with similarity decreasing for east and west facing sites. Fire exclusion resulted in an initial increase in woody species and a subsequent increase in herbaceous species. iii Growth response of H. kraussii was unaffected by catenal position and fire exclusion period, whereas defoliation of surrounding grass tended to increase in size (P<0.05). Density and height for this species however increased with increasing fire exclusion. An increase in soil moisture negatively affected H. kraussii growth indicating susceptibility to high water tables. The number of other woody species establishing beneath H. kraussii may be due to changes in the transmission of light through the canopy where an increase in canopy diameter resulted in an increase of photosynthetically active radiation at the soil surface. The effects of fire on landscape change were investigated for the Eastern Shores and Tewate Wilderness Area, iSimangaliso Wetland Park, South Africa using aerial photography. Changes to historical disturbance regimes largely through active exclusion of fire resulted in the majority of the higher lying coastal grasslands changing to savanna scrub or closed canopied forest within 63 years on the Eastern Shores. The degree of fragmentation of these grasslands was greatly reduced within the Tewate Wilderness Area where disturbance regimes included greater frequencies of fire. Hygrophilous grasslands remained largely unaffected by woody encroachment but did not preclude woody species establishment indicating possible susceptibility during long drier periods. Frequent fires result in the maintained distribution of the higher grasslands. This vegetation type is a system which becomes resilient in response to fire, whereas in the absence of fire readily progresses to Dune Forest. The coastal grasslands above the high water table are therefore highly unstable and transformed easily in the absence of regular disturbance. It would appear that a threshold of approximately six years exists, after which substantial management intervention may be required to reverse the succession back to grassland. The growth of H. kraussii was unaffected by fire and remained persistent irrespective of fire exclusion period. An ability to attain size (height and canopy diameter) was limited with increased soil moisture but density was reduced through regular burning. Frequent fires are necessary to reduce density of H. kraussii and reduce the competitive advantage gained with age.
    URI
    http://hdl.handle.net/10413/10764
    Collections
    • Masters Degrees (Grassland and Rangeland Science) [51]

    Related items

    Showing items related by title, author, creator and subject.

    • Can small-scale poultry production contribute to household food security in the Maphephetheni lowlands, KwaZulu-Natal? 

      Mosisi, Moleka Pange. (2009)
      This study investigated the feasibility of small-scale poultry production to contribute to household food security in the Maphephetheni lowlands in KwaZulu-Natal. Forty households, selected by stratified random sampling ...
    • Aspects of the conservation of oribi (Ourebia ourebi) in KwaZulu-Natal. 

      Grey, Rebecca Victoria. (2006)
      The oribi Ourebia ourebi is probably South Africa's most endangered antelope. As a specialist grazer, it is extremely susceptible to habitat loss and the transformation of habitat by development. Another major threat to ...
    • Investigating the potential of Thuthukani as a viable community garden : a situation analysis. 

      Ngobese, Nokulunga. (2014)
      The concept of community garden has been studied in many parts of the world to understand its role in sustainable land use, food security and cultural cohesiveness. In South Africa, the government is exploring the upliftment ...

    DSpace software copyright © 2002-2013  Duraspace
    Contact Us | Send Feedback
    Theme by 
    @mire NV
     

     

    Browse

    All of ResearchSpaceCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsAdvisorsTypeThis CollectionBy Issue DateAuthorsTitlesSubjectsAdvisorsType

    My Account

    LoginRegister

    DSpace software copyright © 2002-2013  Duraspace
    Contact Us | Send Feedback
    Theme by 
    @mire NV