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University of Cape Town (2000)

The effects of different burning regimes on grassland phytodiversity

Uys, Roger Gregory

Titre : The effects of different burning regimes on grassland phytodiversity

Auteur : Uys, Roger Gregory

Université de soutenance : University of Cape Town.

Grade : Master of Science (MS) 2000

Résumé partiel
The southern African grassland biome has a diverse flora including many rare and endangered species deserving a high conservation priority. With less than two percent currently conserved, proper management of this biome is crucial to maintaining its diversity. Fire, in particular, is important and although there has been extensive research into the grazeable component of the sward, little attention has been paid to the effects of burning on forbs or the overall phytodiversity. The aim of this study was examine the effects of different burning regimes on grassland phytodiversity. To do this, three long-term burning trials, widely located across the biome and consisting of a range of treatments randomly allocated to plots in replicated block designs, were sampled. Manipulated according to the frequency and season of burn, with fire protection controls, diversity was sampled at different scales across a range of treatments. In addition, a range of sward attributes was sampled in an attempt to explain diversity patterns. Diversity was sampled at each site using the importance-score method. This provided measures of the species richness and rare species (species occurring in 3 plots). The effect of frequency and season of burn on species richness was then used to test the predictions of the intermediate disturbance hypothesis (IDH). Ordination techniques and dissimilarity comparisons were used to compare the species composition between the replicates of each treatment and between treatments. Effects of the different treatments on vegetation patchiness were also examined at the plot scale at each site and beta diversity sampled at one of the sites. Species richness was also related to the biomass sampled at each site and calculated from the relationship between rainfall and biomass across the biome. Further, the response of a "range of sward attributes, including : percentage cover, light attenuation and biomass, to the burning treatments was examined. Due to the lack of basic biological information on the grassland forbs, the taxa recorded at each site were tabulated by family, and the underground organs of the forbs examined


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