Although controlled burning has been used to manage Highland Sourveld
grasslands, little was known of its effects on the vegetation. This
study examined the effects of past fire treatments on veld condition,
species composition, dry matter production, quality and canopy recovery
growth rates of these grasslands. Also, six techniques of estimating
the species composition of grasslands were compared in order to decide
on a standard technique for monitoring these grasslands. From this
work it was concluded that the wheel point method is the most satisfactory.
Veld condition scores were significantly lower in grassland protected
from fire than where veld had been burnt or burnt and grazed at regular
intervals. Frequent defoliation was found to maintain the grassland
composition largely unchanged over a period of 30 years. Individual
species were, however, found to react strongly to defoliation frequency.
Plant demographic studies were therefore carried out to explain this
differential response to burning. Three Decreaser and two Increaser I
species were studied.
In all species examined, recruitment of secondary tillers was stimulated
by regular burning, each species being well adapted to a regular fire
regime. Differential responses to burning were best explained by the
combined effects of the different reproductive capacities and mortality
rates of tillers of these species. A biennial spring burning regime was shown to be most suitable for maintaining the most important grass
species at their present levels of abundance.
Annual winter and biennial spring burning did not result in significant
differences in dry matter production. Maximum net productivity was
approximately 230 g/m² in both treatments, placing them amongst the
more productive areas of Southern Africa.
Examination of canopy recovery growth rates showed that there is little
difference in the percentage canopy cover at the end of the growing
season when veld is burnt annually in winter or biennially in spring.
However, differences in season of burn resulted in exposure to erosive
forces at different times of the year.
The results of this investigation have highlighted the importance of
regular burning during the dormant period in the montane grasslands of
Natal. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1985.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10906 |
| Date | January 1985 |
| Creators | Everson, Colin Stuart. |
| Contributors | Tainton, Neil M. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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