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Vegetation, fire and herbivore inter-relationships in the Songimvelo Game Reserve : a landscape ecological approach towards analysing pattern and change

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dc.contributor.advisor Balkwill K en
dc.contributor.advisor Witkowski ETF en
dc.contributor.author Stalmans ME en
dc.date.accessioned 2016-09-22T11:14:13Z
dc.date.available 2016-09-22T11:14:13Z
dc.date.created 1995 en
dc.date.submitted 2002 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/106374
dc.description.abstract The aims of the landscape ecological study undertaken in the 49,000 ha Songimvelo Game Reserve in south-eastern Mpumalanga Province of South Africa were to:<br><br> 1 describe the spatial vegetation pattern and elucidate its causal environmental factors;<br> 2 describe the spatio-temporal characteristics of fires and the resulting pattern on the landscape;<br> 3 determine habitat availability and its relative quality for wild herbivores;<br>4 relate the herbivore numbers and distribution to the vegetation and fire pattern at relevant ecological scales; and<br> 5 establish an Information Management System documenting the above elements and their pattern in time and space.<br><br> The consolidation of the available survey and monitoring data resulted in a database (related to a GIS) consisting of 100 linked tables, with more than 87,500 individual records containing in excess of 1,000,000 individual fields.<br><br> The vegetation is highly diverse with representation of three biomes; savanna, grassland and forest. The composition of the 19 distinct plant communities is determined through an intricate combination of environmental factors. Each community, through its specific species assemblage, structure and location forms a distinctly different habitat in terms of its value to the various species of herbivores. At a macro-level, the extent of mixed and sour grassland was determined by classification and groundtruthing of remote sensing imagery. The mixed grasslands covered only 31.0% of the area but accounted for 66.1% of the game biomass. Water is widely distributed and is not a limiting factor to habitat selection. Based on a GIS analysis, the qualitative difference between mixed and sour grasslands overrides quantitative differences in forage availability, fire history and human disturbance in influencing herbivore distribution.<br><br> In contrast to the tightly regulated fire management generally applied in protected areas in southern Africa, a laissez-faire approach to fire has been permitted over the last 13 years. More than 1,300 individual fires have been documented. Fire return periods are in line with generally accepted management prescriptions for similar areas. The broad frequency distribution around the mean probably conforms more to a 'natural' fire regime than the fixed or mechanistically-determined fire return period prescribed under traditional protected area management systems. The annual number of fires, number of individual patches and number of classes with different fire histories occurring in a moving window across the landscape were consistently higher compared to a theoretical small-scale or large-scale fixed fire regime. The observed fine-scale, dynamic fire pattern and high value of landscape indices suggests that the current laissez-faire approach is appropriate for the maintenance of biodiversity.<br><br> The interaction between the climate, environment and vegetation governs herbivore distribution and density in the SGR in a spatially hierarchical manner. At the highest hierarchical order, the broad division in mixed and sour range determines overall herbivore density patterns. Although of overriding importance, this higher level of hierarchy may be temporarily superseded by effects at a secondary level of hierarchy such as fires. At the third level of hierarchy, nutrient accumulation through termite activity, dung middens and especially human settlements controls herbivore feeding and activity patterns. Within the SGR, the most obvious grazing optimisation process occurs at a small spatial scale. Nutrient-enriched patches, mostly located on the site of abandoned human settlements, are spread throughout a matrix of lesser- utilised veld. The nutrient values recorded for the matrix are below the threshold level to maintain animals throughout most of the year. The enriched patches diverge from this threshold level. A conceptual 'threshold model of resource availability' emerges with clear differences between the 'natural' and the present (man-influenced) landscape. Within a matrix of generally insufficient resource quality, small patches are lifted above the nutritional threshold through concentration of nutrients as a result of overnight impoundment of cattle, intensive utilisation and urine and dung feedback. The old settlement sites clearly constitute a key resource in this landscape.<br><br> The most important and applicable management 'lessons' from this study are:<br><br> 1 Firstly, ensure consolidation, storage and analysis of all monitoring and research data in a database and GIS system.<br> 2 Secondly, incorporate spatial understanding of the area and system under consideration recognising patches as functional components of the landscape.<br> 3 Thirdly, put the classic South African grazing and fire management paradigm in perspective by adopting a contextual scaled view to perceived local problems. en
dc.language English en
dc.title Vegetation, fire and herbivore inter-relationships in the Songimvelo Game Reserve : a landscape ecological approach towards analysing pattern and change en
dc.type Doctoral degree en
dc.description.degree PhD (Science) en


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