Grasslands of Umtamvuna Nature Reserve, KwaZulu-Natal : a description and recommendations for monitoring.
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Date
1995
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Abstract
The main aim of this study was to classify and map the threatened coastal
grassland communities of the 3 257 ha Umtamvuna Nature Reserve (UNR) in
KwaZulu-Natal (30°07'30" to 300 11'05"E; 30°55'00" to 31°04'30"S).
Secondary aims were to relate past management and selected environmental
variables to community composition and to develop guidelines for monitoring.
Alpha diversity was measured using a Whittaker plot and revealed 119
species. A pilot study to test the efficiency of botanical techniques showed
that a point based technique (nearest plant method in a 20 X 20 m plot) was
efficient (52 minutes for recording 200 points), but recorded only 23% of the
species. By increasing the number of points to six hundred, 34% of the
species were recorded in 178 minutes; the same time was required to
randomly place 30 quadrats (50 X 50 cm), which revealed 80% of the
species. Tests for replicate similarity showed a high retrieval of internal
association (PS = 86%), using abundant species only and 100 points per plot.
The point based technique was thus efficient in detecting abundant species
and was acceptable for producing a classification, especially in this case
where a comprehensive species list already existed.
Indirect gradient analysis (TWINSPAN) identified six grassland communities.
An ordination using detrended correspondence analysis (DCA) contributed
towards the community classification and grazing and fire frequency gradients
were inferred from this ordination. Protea roupelliae communities were
common but did not influence grass species composition . Canonical ordination revealed that, of the eight environmental variables measured, 'distance from
the sea' strongly affected species distribution (r= 0.83).
Cost effectiveness was considered in the development of a monitoring
programme. Point based monitoring techniques favoured by sourveld
researchers in KwaZulu-Natal were found to be inefficient, particularly for
studies requiring the measurement of both species richness and community
composition. Randomly located 100 X 100 cm quadrats, located in selected
sites which represent previously identified communities, was more efficient.
This study contributed towards a refinement of information on the grassland
communities of KwaZulu-Natal and supported the use of point data for the
classification of grasslands not previously studied. It also demonstrated that
point based techniques were not suitable for meeting all grassland monitoring
requirements.
Description
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1995.
Keywords
Grassland ecology--KwaZulu-Natal., Umtamvuna Nature Reserve (KwaZulu-Natal), Theses--Grassland science.