9806310 Connell A long-term study of tree populations in tropical and subtropical rain forests in Australia has been carried on for 34 years. The objective has been to elucidate the processes and mechanisms that are responsible for the high species diversity and the varieties of population structures among the many species in these forests. Long-term data have been collected on rates of seedling recruitment, and on growth and mortality of all sizes of all species of trees in these forests. In recent years the intensity of flowering and fruiting of adult trees of 103 species, and the subsequent germination and survival rates of new seedlings, has also been measured. This study is among the longest done on tropical and subtropical trees, and is the longest for the seedling and sapling stages. This study will test the hypothesis that diversity is maintained in these forests because spatially common species have lower rates of reproduction, growth, and survival than spatially rare species. Other hypotheses to be addressed are: (1) that many species coexist by specializing to live in different habitats, (2) that diversity confers advantages which increase growth and survival of seedlings, and (3) that local (insects) and regional (rainfall) factors interact to affect diversity in these forests. Overall, this project will advance our understanding of the different factors that lead to high tree species diversity in tropical and subtropical rainforests. These are some of the most complex and diverse ecological communities known, and contain a high proportion of the worlds terrestrial species of organisms. Detailed, long-term studies such as this one will contribute to an understanding of factors that control diversity in these forests, and therefore help to manage and preserve their integrity.
