Rain forest is characterized by its structural complexity floristic richness, and the equity of distribution of the available resources amongst the species. It is suggested that our understanding of the dynamics of rain forest and the success or otherwise of our attempts to utilize, manage, and even reconstruct the resources which rain forests offer, depend primarily on our understanding of the factors which permit the natural existence of such a complex system. This thesis presents the results of an investigation aimed at elucidating the factors responsible for the maintenance and formulation of the observed species' spatial and diversity patterns in primary and secondary Complex Notophyll Vine fore in Lamington National Park in south-east Queensland.
Eight one- hectare sites (each gridded into one hundred contiguous quadrats) were sampled. Four of these sites were situated in primary forest. The remaining four sites were secondary forest sites of different ages and known histories. The species and size of each individual larger than 0.457m high were recorded in each quadrat in each of the sites. Additional secondary forest sites were used for reference purposes.
The spatial species patterns in three of these sites (two primary forest sites and one secondary forest site) were studied using a number of classificatory techniques. Although it was possible to delineate areas within both primary and secondary sites which were characterized by local increases in abundance of particular species, in particular size classes these 'patches' appear to have little phytosociological significance. These patches are not characteristics in terms of their overall floristic content, nor are they characterized by the presence or absence, or differences in abundance, of species in other size classes. The degree of pattern shown by the individuals of the species decreases during succession. In the primary forest, the least pattern is shown by the canopy individuals. Although the rain forest species do reflect variations in physical environmental factors (e.g. gullies, aspect, soil depth etc. ) , the distribution of the individuals of the species across smaller areas comparable to the size of the experimental sites is postulated to be primarily a product of the regenerative mechanisms of the forest as suggested by Poore (1968) and others. These general mechanisms are described; they are consistent with those proposed by van Steenis (19 58a, 19 5 8b).
The patterns of species diversity (species richness, equitability of distribution of the individuals amongst the species, and the spatial intermingling of the individuals of the different species) were examined in all eight one hectare sites. During species succession, and during growth towards the canopy in the primary forest, the following dominant trends are evident: -
(i) Increased species richness per site per individual.
(ii) Increased equitability of the distribution of the individuals amongst the species in the total site samples.
(iii) Increased spatial inter dispersion of the individuals of the different species.
These trends are discussed in relation to the results of both the pattern analysis studies presented in this investigation and the results of other pattern and diversity studies in rain forests.
The possible mechanisms contributing to the maintenance, and formulation during succession, of the observed spatial and diversity patterns are discussed. Seed dispersal, seed germination, and early seedling mortality data collected on a number of rain forest tree species are presented to aid in the interpretation of these mechanisms. It is concluded that no unique mechanism is required to explain the observed species spatial and numerical distributions in primary and secondary forests. It is postulated that the evolutionary process in the comparatively favourable and predictable environment of rain forest has produced a system in which more species can coexist by temporal and spatial 'avoidance' than could exist in a more rigorous or less predictable environment. The species specializations on the biological environment (interactions, interference, regenerative strategies) are considered to be more important in determining the spatial and numerical interrelationships of the species than are specializations on the physical environment. These ideas are related to existing ecological theory, and the practical considerations of such a process are considered.