Scale dependence of tree abundance and richness in a tropical rain forest, Malaysia

Abundance and richness are the two fundamental components of species diversity. They represent two distinct types of variables of which the former is additive when aggregated across scales while the latter is nonadditive. This study investigated the changes in the spatial patterns of abundance and richness of tree species across multiple scales in a tropical rain forest of Malaysia and their variations in different regions of the study area. The results showed that from fine to coarse scales abundance had a gradual and systematic change in pattern, whereas the change in richness was much less predictable and a 'hotspot' in richness at one scale may become a 'cold-spot' at another. The study also demonstrated that different measures of diversity variation (e.g., variance and coefficient of variation) can result in different or even contradictory results which further complicated the interpretation of diversity patterns. Because of scale effect the commonly used measure of species diversity in terms of unit area (e.g., species/m²) is misleading and of little use in comparing species diversity between different ecosystems. Extra care must be taken if management and conservation of species diversity have to be based on information gathered at a single scale.