Browsing by Subject "Vegetation"

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    Open Access
    A population dynamics model for analysing the effect of rainfall seasonality on vegetation in the Karoo
    (2025) Govender, Serayen; Altwegg, Andreas
    The flora of the Cape Floristic Region is amongst the most diverse and unique on the planet, due mainly to the unique climate of this region. The effects of climate change are threatening many sensitive ecosystems around the world and so it is important to understand how factors of climate change may affect the Cape Floristic Region. This paper investigates the effect of changing rainfall seasonality on certain important species of plants in the Cape Floristic Region. The species are selected from different biomes and I focus on two growth forms, namely reseeder and resprouter. Data from an experiment conducted between two biomes in the Cape Floristic Region is used to model the growth of the two growth forms post- fire. Rainfall in this experiment is artificially manipulated on replicated plots at the two experiment sites. The population growth is modelled using state-space models, incorporating both an ecological process model and an observation model. This allows us to account for errors both in the observation of the data as well as in the natural variability in the biological state process that generated the data in order to account for both measurement and process error. My results suggest that increased summer rainfall in the Cape Floristic Region has a positive effect on the populations of reseeder species in both biomes and has little effect on the populations of resprouter species. A multivariate state-space model is also proposed to investigate the effects of interactions of species growth, within the replicated plots.
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    Open Access
    The Vegetation and Restoration Potential of the Arid Coastal Belt Between Port Nolloth and Alexander Bay, Namaqualand, South Africa.
    (1996) Desmet, Philip George; Richard Cowling and Dave Richardson, Kristal Maze
    This thesis introduces the environment and the vegetation of the Namaqualand coastal belt between Port Nolloth and Alexander Bay. Aspects of the abiotic environment are discussed and related to patterns and processes observed in the vegetation of the study area. The restoration of the natural vegetation impacted by diamond mining activities is discussed. 1-4 The study area, located within the winter rainfall area of the Namib Desert, is one of four global fog deserts. The area is characterised by a near ubiquitous covering of Recent to Tertiary amorphous dunes of marine origin. The dunes can be divided into two broad categories: Recent, mobile white dunes, and Tertiary to Late Quaternary, semi-mobile red dunes. The red dune soils are considered arenosols, underlain by dorbank and calcrete hardpans, whereas the white dunes generally lack this structure, unless they are superimposed on an older dune series. The dune landscape is interrupted by outcrops of bedrock, such as river canyons (Holgat River); inselbergs (Buchu Twins); and koppies. Gravel plains and rocky outcrops cover much of the area on the south bank of the Orange River, as far south as Cape Voltas. The low rainfall.