Contrasting successional stages lead to intra- and interspecific differences in leaf functional traits and herbivory levels in a Mexican tropical dry forest

We analyzed leaf functional traits, chemical defenses and their effects on herbivory in three plant species that occur at two contrasting successional stages: mature and secondary forests in Mexico. In each successional stage, 15 individuals of Cordia elaeagnoides , C. alliodora and Achatocarpus gracilis were selected to analyze physical and chemical defenses and herbivory. Chlorophyll content, leaf thickness, leaf water content and leaf fresh mass were higher in mature forests, whereas SLA was higher in secondary forests, partially supporting the prediction that leaf traits vary from conservative to acquisitive along the leaf economics spectrum during succession. Content of secondary compounds did not show a consistent pattern among successional stages, but a relatively consistent trend was observed for C. elaeagnoides and A. gracilis , which exhibited higher levels of phenols and flavonoids in mature forests. Herbivory was higher in secondary than in mature forests for Cordia species, but the opposite pattern was found for A. gracilis . These results contradict the predictions of the resource availability hypothesis for tropical dry plant species, which state that resource-conservative plants in secondary forests invest more in chemical defenses and have less herbivore damage than resource-acquisitive plants in mature forests. Such idiosyncratic responses make it difficult to use a single hypothesis to predict plant defense and herbivory variations along environmental gradients at both intra- and interspecific levels. Considering the current intensity of human disturbance in forests, further studies are necessary to evaluate the impacts of changes in leaf functional traits on plant fitness during succession in the tropics.