Thesis (MTech (Nature Conservation))--Cape Technikon, 2003. / The study was carried out on two adjacent farms on the plains of the Nama Karoo near
Beaufort West. The impacts of three grazing treatments (a) zero grazing (b) non-selective
grazing (c) conventional grazing, on plant diversity and certain vegetation parameters were
compared.
Unpredictable and variable rainfall and major disturbance events such as droughts drive
vegetation change in the Nama Karoo. Major recruitment events are rare and can determine
Karoo vegetation composition for many years. The diversity of plant species plays an
important role in determining vegetation composition during major recruitment events and
following drought or disturbance such as grazing.
Grazing can influence the composition, abundance and seed production of Karoo plants and
in so doing influence the future abundance of desirable and undesirable forage species.
These changes may only become evident over long periods, but small changes in vegetation
as a response to grazing treatment can accumulate considerably over time.On the farm Elandsfontein, studies have shown that non-selective grazing leads to a higher
plant turnover rate, resulting in more vigorous and productive plants, and improved
ecosystem functioning. However there is no evidence of this grazing system promoting or
reducing plant diversity. The aim of this study was to test whether the non-selective grazing
system promoted or reduced plant diversity compared to no grazing and conventional
grazing. The hypothesis was that there were no differences between the grazing treatments
in terms of plant diversity or any of the vegetation parameters measured.
To evaluate this hypothesis, plant data were collected from the three grazing treatments
using the Modified-Whittaker vegetation sampling method. The method was further
modified for this study to allow for accurate abundance measurements rather than estimates,
and an increased area for recording species richness. Using various diversity indices that incorporate species richness and the proportional
abundance of species, plant diversity values for each treatment were obtained.
No differences in terms of plant diversity were found between the treatments.
A significant difference between treatments was found in the density of plants, particularly
in perennial grasses and shrubs. Canopy cover percentage did not differ for individual
species or as total cover between the treatments.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/2030 |
| Date | January 2003 |
| Creators | Wheeler, Alan David |
| Contributors | Beukes, P., Dr |
| Publisher | Cape Technikon |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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