Palaeoecology, Fire Management and Vegetation Dynamics in the Cederberg Wilderness Area, South Africa

8 Feb 2007 Cederberg Wilderness Area, South Africa, Africa Habitats

Lindsey Gillson

To evaluate the effects of past land use changes and fire history on the vegetation of the Cederberg Wilderness Area, and to explore the implications for conservation management.

The Cederberg lies 200km north of Cape Town, South Africa, is part of the Cape Floristic Region and is a meeting point of three biomes, the Fynbos, Succulent Karoo and Nama Karoo. The Cederberg is also a centre of endemism with over 280 plant species occurring here and no where else. The Cederberg is named after the Clanwilliam cedar (Widdringtonia cedarbergensis) which is found on rocky outcrops and summits between 1000 and 1700 m above sea level and is an endangered species. The Cederberg Wilderness Area covers over 72 000 ha and is managed by Cape Nature Conservation, with the aim of maintaining a fire regime that is conducive to the persistence of Fynbos vegetation and the survival of Widdringtonia cedarbergensis.

Currently, there is little long-term information on fire history and its impacts on vegetation, and our study will be unique in investigating changing fire regimes of the area and in its vegetation composition in the last 500 years. Our aims are to evaluate the effects of past land use changes on the vegetation of the Cederberg and to explore the interplay between fire history and vegetation dynamics over the last 500 years. We have identified four management phases: 1) pastoralist 2) colonial settlement (from 300 years ago) 3) resource extraction (from c. 1900 – 1973) and 4) wilderness (form 1973). Our project will investigate the fire history in each of these management phases and its effect on vegetation, thus providing a context for evaluating the effects of current management practices.

We will use palaeoecologically techniques to examine changes in vegetation composition and fire history. Pollen and charcoal from sedimentary cores collected from wetland areas will be analysed in order to reconstruct the vegetation and fire history of the Cederberg Wilderness Area. A high resolution core, covering the past c. 100 years, will be used to calibrate the charcoal record with known fire events recorded in historical documents. This calibration exercise will increase confidence in the interpretation of longer term records covering the four management periods described above. Using chosen indicator species and charcoal abundance we will investigate how the proportion of fire tolerant to fire sensitive species, including the Clanwilliam Cedar (Widdringtonia cedarbergensis), change over time in response to fire history.

A suitable fire regime is crucial to the survival of fynbos vegetation, and the project could benefit the estimated 2000 plant species found in the area including 280 species of endemic plants, including the endangered Clanwilliam cedar. The conservation and management implications of the palaeo-data will be explored in consultation with Cape Nature Conservation.

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