PLANT COEXISTENCE IN COASTAL HEATHS - FLORISTIC PATTERNS AND SPECIES ATTRIBUTES

An investigation was made of plant coexistence in coastal heaths. A 4k m stretch of Pleistocene beach sand was selected, and patterns of vari ation in heath vegetation on ridges and slopes in the beach system wer e studied. The sampling design covered variation with geographic dista nce among transects, plots within transects and quadrats within plots which were orthogonal to the alignment of ridges and slopes. Cover of vascular plant species was scored within each quadrat and both multiva riate and univariate analyses tested the hypothesis that variation in the data was associated with environmental difference and geographic d istance. There was a strong floristic variation between the ridge and slope habitats. However, within these habitats there was no significan t variation with distance at scales of kilometres, nor at hundreds of metres within transects nor at tens of metres within plots in floristi c composition, in numbers of species, and in cover. Though differing f loristically, the vegetation of the slopes and ridges had similar curv es of importance values and fairly similar spectra of life forms and f orms of post-fire regeneration in their constituent species, although the ridges had slightly more obligate-seeding species and fewer specie s of sedges and herbs than the slopes. The two habitats shared several genera, however, within such genera, species with similar attributes mostly occurred in different habitats. Hypotheses were suggested to ex plain segregation of species between the two habitats and the coexiste nce of species within habitats. Since patterns of variation among habi tats were consistent over both smaller and larger scales of distance e xamined, experiments to test hypotheses may be designed so that their findings might be applied generally to the whole system studied.