Life on a leaf: the development of spatial structure in epiphyll communities

1. The spatial structure of biotic communities can be shaped by niche-based or stochastic processes, and the importance of both can change through time. Niche-based processes include neighbour interactions, which can change in intensity and quality as communities develop in dependence of environmental conditions. Epiphylls, miniature communities of liverworts, lichens, algae and fungi on leaves, develop only in relatively moist forests, but their leaf-surface habitat is still characterised by moisture stress, especially in more exposed parts of the forest. As neighbours may alleviate moisture stress, we expected that in forest gaps (dryer, brighter) epiphyll communities would show more positive neighbour interactions, resulting in more clustered spatial patterns, than in closed forest, in accordance with the stress-gradient hypothesis.

2. To understand how the processes shaping epiphyll communities change through time and differ between gaps and closed forest, we examined the fine-sc...