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Biodynamics of the Eastern Cape Thicket Biome

Project overview

The Terrestrial Ecology Research Unit (TERU) of the University of Port Elizabeth was contracted to complete the Eastern Cape sector of the Conservation Farming project being run by the National Botanical Institute. The project aimed to compare the impacts of traditional and innovative "biodiversity-friendly" farming methods on biodiversity and ecosystem processes in agricultural landscapes across South Africa. The project was initiated in April 1999 and was due for completion in December 2002.

Two PhD students, Ayanda Sigwela (Zoology) and Richard Lechmere-Oertel (Zoology and Botany), were working on quantifying the changes in ecosystem function and biodiversity on farms with different management histories. Their projects were supervised by Graham Kerley and Richard Cowling of TERU.

Soil ecology and biodiversity

Richard Lechmere-Oertel worked primarily on quantifying changes in the soil ecosystem, particularly soil-water retention and run-off and the implications of micro-climate changes on decomposition processes. Experiments designed to capture run-off from 100m² catchments have been established on several fence-line contrasts. Litter traps, bags and packs have been set out to measure litter fall and decomposition over 15 months in several sites across a degradation gradient. A series of climate data loggers were established in these sites to measure micro-climate inside and outside of bushclumps. During this period, plant and faunal diversity assays were conducted as well as several soil chemical and physical analyses.

Plant reproductive dynamics

Ayanda Sigwela assessed plant sexual reproduction, focusing particularly on seed and seedling dynamics. He tested the hypothesis that large mammals are important dispersers of thicket seeds. Seeds were extracted from samples of elephant, rhinoceros, buffalo, eland, kudu, bushbuck, and duiker faecal material collected from Addo Elephant National Park. Bird latrines have also been set out along the degradation gradient to quantify the potential of birds to disperse seeds into degraded areas. Ayanda has measured the abundance and microsite environment of seedlings across the degradation gradient and has set up experiments to measure death due to predation or environmental stress. Soil seed banks were also quantified.

Vegetation dynamics and rehabilitation

Much of this work was aimed at understanding the dynamics of Succulent Thicket with the ultimate aim of looking for a path towards rehabilitation. This will benefit many farmers who have reduced their goat stocking rates and are moving towards farming game animals.