Herbivory as a Canopy Process in Rain Forest Trees

It has long been assumed that forests represented vast expanses of homogeneous green tissue, but this assumption is oversimplified. When walking through a forest, we usually focus our observations on a narrow band of green foliage, from ground level to about 2 m in height. This represents at most 10% of the foliage in mature forests, with the rest often high above our heads and consequently beyond our observations. Because the majority of plant-herbivore relationships occur where the foliage is located, it is obvious that herbivory as a forest process remains relatively unknown. Fifteen years of observations on herbivory in canopies have given me a different perspective: I no longer see forests as expanses of green, but instead I see them as great mosaics of holes in leaves! As human beings making observations over relatively short time spans, we usually fail to appreciate the dynamic processes that separate life from death in complex canopy ecosystems. The life of a leaf, which comprises the building block of the forest canopy, is no exception. In a leaf's life span, it