High foliicolous lichen alpha-diversity on individual leaves in Costa Rica and Amazonian Ecuador

Two individual, dicotyledoneous leaves (125 and 98 cm² in size) and one composed palm leaf (c. 6800 cm² in size), gathered at La Selva Biological Station, Costa Rica, and Jatun Satcha Biological Station, Amazonian Ecuador, were screened for small-scale foliicolous lichen diversity. On the dicotyledoneous leaf from Costa Rica, 49 lichens and one lichenicolous fungus were found, while a comparable leaf from Ecuador revealed 46 lichens and two lichenicolous fungi. The palm leaf yielded 81 lichens and one lichenicolous fungus. This is the highest alpha-diversity so far reported for foliicolous lichens on individual leaves and invites for comparison with tree diversity in tropical rain forests. Due to the high proportion of species represented by a single thallus, the taxonomic diversity of lichens on individual leaves (or trees in selected plots) cannot be self-supporting, but reflects a high degree of dispersion or entropy within the community of which the individual leaf (or selected plot) is part. Diversity is therefore fractal, showing similar patterns at different scales, each part of a given community reflecting the entire community. Thus, mechanisms that result in high small-scale diversity must be looked for at the community level.