Eighty three of Acocks's sites, originally surveyed about 50
years ago, were resurveyed in 1996 to determine the extent of
grassland change in the humid grasslands of KwaZulu-Natal. Sites
were relocated using 1:10 000 scale ortho-photos and present land
cover was determined for each site. Forty six of the sites that
were still under original grassland were further examined to
determine present species composition. A survey method was
designed that would emulate Acocks's data and comparisons were
drawn between original and present species composition. These
differences were then analysed together with some environmental
variables to try to determine the factors which had the most
influence on the change and which environment and management
factors are related to the present variation in composition among
sites.
Of the 83 sites, 26 had changed from natural vegetation to some
other form of agriculture such as forestry or cultivation. Most
of this change had occurred in the Natal Mistbelt Ngongoni Veld
where large areas are forested. Cultivation is found
predominantly in the communal areas where subsistence, cultivation
practices are employed.
The remainder of the sites had changed significantly in terms of
their species composition. The most pronounced change had
occurred in areas under communal tenure although significant
changes had occurred in the commercially farmed areas. The
direction of change was also more consistent towards species that
commonly predominate in heavily grazed areas in the communal
areas compared to the commercial areas. The exact reasons for
this were unclear but this could possibly be attributed to
heavier stocking rates in the communal areas.
Change in floristic composition was also more pronounced at lower
altitudes where the mean annual rainfall is lower and the mean
annual temperature higher. This could possibly be a result of the vegetation at lower altitudes being less stable and thus less
resistant to change.
Basal cover differed significantly between commercial and
communally grazed sites. Lower basal cover was found in the
communal sites where intensive grazing limits the growth of
individual tufts. Number of species found at each site did not
differ significantly between communal and commercially grazed
sites.
This study was also a practical implementation of the resurveying
of Acocks's sites and the original data set was found to be a
useful baseline data set to determine coarse long-term changes
in the vegetation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10293 |
| Date | 23 December 2013 |
| Creators | Marriott, David John. |
| Contributors | Morris, Craig Duncan., O'Connor, Timothy G. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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