Phenological indicators of resources offered to leaf herbivores in restinga communities

Abstract

Premise

Plants can limit the leaf tissue consumed by insect herbivores through chemical, structural, and nutritional leaf defenses or by escaping in space and time. Escaping is related to the phenological patterns of plants, which in turn respond to climatic factors. This study evaluated leaf production in a coastal plant community in southern Brazil to test the following hypotheses: (1) Leaves are continuously produced in this ecosystem, and (2) synchrony acts as an escape strategy from herbivory.

Methods

We evaluated leaf production patterns of 20 herbaceous, shrub, and tree species for 2 years using the Fournier index then measured leaf consumption in the second year. The Rayleigh test was used to verify the synchrony of phenological events. Correlations between leaf production and climatic factors and between leaf production synchrony and herbivory were analyzed.

Results

New leaves were continuously produced at the plant community scale, but herbaceous and shrub species showed a phenological pattern distinct from that of tree species. Trees had peaks of synchrony in leaf production that were positively correlated with amount of leaf tissue consumed, refuting the hypothesis that synchrony acts as an escape strategy.

Conclusions

The phenological and herbivory patterns in this plant community may be due to the supply of resources in the soil and the composition of the insect community.