Not so simple after all: searching for ecological advantages of compound leaves

Abstract

Leaves come in many sizes and shapes, and the relationships between leaf traits and the environments they occur in are better understood every day. However we still know very little about the ecological consequences of plants having either compound or simple leaves. We attempted to address this knowledge gap by comparing chemical and physical characteristics (leaf area, length:width ratio, water content, leaf mass per area, 'toughness' and C:N ratio), as well as rates of herbivory between compound and simple leaves across 34 species in adjacent rainforest, open woodland and wet sclerophyll (tall open forest) vegetation in northeastern Australia. We found C:N ratio to be lower in simple leaves, but this was the only leaf trait that differed significantly between leaf types and did not stand up under phylogenetic analysis. Overall, we found no differences in herbivory between simple and compound leaves. While it remains unclear what the advantages of having one leaf type over another might be, the differences do not seem to lie in construction, or in vulnerability to herbivores, at least in the Australian Wet Tropics.