The vegetation and identification of management units of the Honnet Nature Reserve, Northern Province, South Africa

An analysis of the vegetation of the Honnet Nature Reserve, Northern Province is presented. Releves were compiled in 56 stratified random sample plots. The Braun- Blanquet procedure revealed 12 distinct plant communities and four sub-communities. The Variable Quadrant Plot Method was used in the structural analysis of the communities and management units. The data were ordinated using Detrended Correspondence Analysis (DECORANA) to determine possible relations and gradients between and in the plant communities. Six management units were identified by means of the vegetation ordination, plant communities and the physical environment. A hierarchical classification, description and ecological interpretation of the vegetation units and a descrip- tion of the management units are presented.

Vegetation ordination of subalpine meadows using adaptive strategies

The vegetation of subalpine meadows was investigated by several multivariate analytical methods. Detrended correspondence analysis (DCA) revealed overall patterns of vegetation response to environmental gradients and identified many indicator species. Binary discriminant analysis confirmed these interpretations and identified indicator species with more clarity than did DCA. A plant strategy ordination was developed from a morphological index of competitiveness and from a relative growth rate index. Results converge to these conclusions: (i) the strategy ordination was consistent with habitat types and DCA; (ii) the degree of species niche differentiation within a community varied with productivity and disturbance; (iii) morphological and physiological niche differentiation is least in productive sedge meadows and greatest in mesic grasslands where production and disturbance are moderate. The adaptation spectra of species in a community provide useful insights about site conditions, history, and response to manipulations.

Computer display graphics for principal-component analysis and vegetation ordination studies

The interpretation of ordination diagrams obtained from principal-component analysis requires a considerable amount of time-consuming graphical work. Two methods of approach to this problem are described where off-line plotting facilities under the control of a computer-generated tape are used. Examples of both approaches are presented and illustrate both the considerable time saving achieved as well as the power of the methods as research tools.