Thesis (MSc (Conservation Ecology and Entomology)--University of Stellenbosch, 2006. / Swartland Shale Renosterveld is restricted to fertile fine-grained soils in the winter rainfall region of
the Western Cape. Between 91% and 97% of this vegetation type is transformed, mostly due to
agriculture. Remaining fragments have an irreplaceable conservation value due to a high richness of
endemic geophytes. Information on renosterveld vegetation composition and response to
disturbance is sparse. Research occurred at three sites near Wellington: Voëlvlei Provincial Nature
Reserve (CapeNature), Elandsberg Private Nature Reserve (Elandsberg Farms (Pty.) Ltd.), and
Krantzkop munitions factory (Armscor/Somchem) forming a contiguous fragment in the Agter-
Groeneberg Conservancy. The primary research aim was to identify or ascertain patterns of plant
succession in Swartland Shale Renosterveld and associated different-aged old fields (previously
ploughed), with the interaction of grazing. The key research questions are: (1) What are the plant
communities of unploughed renosterveld and different-aged old fields which originated in habitats
of ploughed renosterveld? (2) What are the most characteristic features of the floristic and
ecological relationship between the described plant communities in terms of ecological factors
operating within the studied system? (3) Does total species and life-form group richness differ
between natural vegetation and old fields? (4) Is life-form richness influenced by ploughing and
grazing or the interaction between these disturbances? (5) Is life-form cover-abundance influenced
by ploughing and grazing or the interaction between these disturbances? (6) Does alien plant
species richness differ amongst seres, and with different levels of grazing intensity? A comparison
of life-form richness and cover-abundance of old field vegetation was made with adjacent natural
unploughed “controls”. The effects of ploughing on community structure, with the inclusion of
grazing was established. These life-form richness comparisons also occur across a gradient of
increasing large mammalian herbivore grazing intensity. Sampling was conducted in winter and
spring using nested 1000m2 relevés.
A hierarchical classification, description and floristic interpretation of renosterveld and old field
vegetation were made using TWINSPAN, SYN-TAX 2000 and CANOCO. The samples were
classified with TWINSPAN and two communities were described at the association level, namely:
Ursinia anthemoides–Cynodon dactylon Grassland Community (with two variants) and the
Pterygodio catholici–Elytropappetum rhinocerotis Shrubland Community (with two subassociations),
respectively. The vegetation data were further hierachically classified using SYNTAX
2000 which revealed similar clustering of sample objects to that resulting from classification and ordination. Following ordination of sample objects with CANOCO, select groups of species
were used to depict their response curves in relation to seral development.
Briefly it was found that the effects of grazing vs. non-grazing was more pronounced on old fields
than in unploughed vegetation. Overall total species and life-form richness was reduced by
ploughing with old fields requiring a recovery period of 30 years to resemble unploughed
vegetation.
Keywords: Swartland Shale Renosterveld, phytosociology, vegetation patterns, life-forms,
succession, disturbance, ploughing, grazing, old fields.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/2806 |
| Date | 03 1900 |
| Creators | Walton, Benjamin Alan |
| Contributors | Milton, Sue J., Le Roux, A., Mucina, L., University of Stellenbosch. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 2926212 bytes, application/pdf |
| Rights | University of Stellenbosch |
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