Diversity of Species and Interactions in the Upper Tree Canopy of Forest Ecosystems

SYNOPSIS. The importance of the organisms and processes that occur in forest canopies is becoming increasingly recognized in relation to under- standing biodiversity. The upper tree canopy of many forest ecosystems fosters extremely diverse communities, particularly of vascular epiphytes and arthropods. Epiphytes also contribute to the diversity of birds because they add to the total amounts of resources, provide opportunities for resource specialization, and temporally spread available resources in the canopy throughout the year. Epiphytes also contribute to ecosystem pro- cesses such as nutrient cycling because they gain access to nutrient sources origiaating outside the ecosystem and transfer them to other members of the forest, thus functioning as a "keystone" resource.