A long-term study of tree populations in tropical and subtropical rain forest in Australia has been carried on for 29.5 years. The objective is to elucidate the mechanisms that are responsible for the high diversity of species as well as the variety of population structures (age and size distributions, spatial patterns, life histories) seem in these forests. Trees, saplings and seedlings were identified, tagged and mapped in 1963-65. In subsequent censuses between 1963 and 1992 the growth and mortality of tagged plants were determined, and newly recruited tree seedlings recorded. These data yield rates of recruitment, growth and mortality of all sizes of all species of trees. Other measurements included the timing and location of tree-falls and light gaps and the structure of the overstory canopy. It is planned to continue this study for at least another 2 decades, for the following reasons: 1) to increase the probability of measuring the effects of rate important events (e.g. extremes of weather, population explosions of different species), or of detecting gradual trends, which require long records; 2) to gather information on short-term changes that will help to interpret long-term findings; 3) to obtain information over larger spatial scales to assess the generality off findings. The significance of this research is that it should increase knowledge of the dynamics of rain forest, one of the most complex and diverse ecological communities known, which contains a high proportion of the world's terrestrial species.
