A vegetation survey of the Cape of Good Hope Nature Reserve. I. The use of association-analysis and Braun-Blanquet methods*

Abstract

The survey aimed to establish broad vegetation units that could be mapped on an extensive scale in the Cape of Good Hope Nature Reserve at the southern tip of the Cape Peninsula. This paper compares the performance of two methods, association-analysis and the Braun-Blanquet method as developed by the Zurich-Montpellier School of Phytosociology. One hundred 50 m2  sample plots, covering the whole Reserve, were placed systematically at grid intersections on the 1:18 000 topographical map. at 1 000-yard (914 m) intervals. Species lists, recording merely presence of all species with permanently recognizable aerial parts, were made for each plot. The association-analysis resulted in a classification of 23 final groups of sample plots, of which only five groups showed high floristic and ecological homogeneity. Of the remainder, eight groups contained some anomalous, misplaced plots, and ten represented small, isolated fragments of natural units. The original data were then analysed using Braun-Blanquet methods to provide an independent classification for comparison with the former. The Braun-Blanquet communities were found to be more homogeneous in terms of previously defined habitat groupings and showed floristic relationships consistent with these groupings. It is concluded that, with the type of sampling used, the synthetic phytosociological Braun-Blanquet method provides a more natural classification of plant communities of the Reserve than does the monothetic divisive association-analysis method.