Distance decay in an old-growth neotropical forest.

摘要

This study was conducted to answer the following issues: (1) does distance decay exist in an old-growth neotropical forest?; (2) is this distance decay stronger than expected due to environmental heterogeneity alone?; and (3) at what spatial scales are distance decay manifested? An index of distance decay was applied appropriately for small quadrats (the probability of encountering a conspecific tree) to a grid of 0.01-ha plots (n=1170) at the La Selva Biological Station in Costa Rica. A null model was used to account for environmental heterogeneity. A significant, but weak, distance decay was found. After correcting for known patterns of environmental heterogeneity, the distance decay almost disappeared, except for fine spatial scales. These results are inconsistent with models that predict distance decay at all spatial scales. However, biological processes leading to distance decay may be more relevant and detectable at scales broader than this study. Research utilizing objectively-located samples over much broader scales is necessary to evaluate the generality and magnitude of distance decay.