Summary 1.A key issue in plant/herbivore interaction research is to understand which plant traits drive differences in herbivore damage. Variation in chemical, physical or phenological traits of plants may all modulate the degree of herbivore damage among species and individuals, yet the relative importance of these factors is still subject to debate, particularly in species-rich systems such as tropical rain forests. 2. To address this issue, we quantified leaf herbivore damage in 28 common tree species of the Yasunı forest dynamic plot (YFDP) in the Ecuadorian Amazon over 11 months. Census data from the YFDP allowed us to quantify several aspects of tree ecology potentially affecting herbivory including leaf turnover and spatial distribution patterns. We measured six chemical, eight physical and four ecological traits of the focal species. Using a combination of multivariate analyses and phylogenetic generalized linear regression model (PGLS), we assessed trade-offs between physical and chemical traits and the relative effect of all these traits on leaf herbivore damage. 3. Herbivore damage was highly variable among species and individuals, with leaves on average displaying damage over 13.4% (2.5-29.5%) of their area. We found no significant trade-off between physical and chemical defences for the 28 studied tree species. Overall, leaf size, shearing resistance, cellulose, ash content and leaf size 9 ash were the best predictors of herbivore damage. Surprisingly, condensed tannins and latex did not significantly correlate with herbivore damage. In addition, we found no relationships between herbivory and local tree density. However, we did find a weak effect of tree clustering and strong effect of tree leaf turnover rates on herbivore damage. 4. Synthesis. In the western Amazon, leaves are defended against herbivores through a combination of physical (toughness), chemical (toughness-related elements), and phenological (rapid leaf replacement) characteristics that do not appear to be subject to obvious trade-offs. Conventional strategies, such as condensed tannins or latex, do not seem to be strongly involved as a defence against herbivores in this community.

SummaryIt is commonly accepted that plant responses to foliar herbivory (e.g. plant defenses) can influence subsequent leaf-litter decomposability in soil. While several studies have assessed the herbivory-decomposability relationship among different plant species, experimental tests at the intra-specific level are rare, although critical for a mechanistic understanding of how herbivores affect decomposition and its consequences at the ecosystem scale.Using 17 tree species from the Yasun ı National Park, Ecuadorian Amazonia, and applying three different herbivore damage treatments, we experimentally tested whether the plant intra-specific responses to herbivory, through changes in leaf quality, affect subsequent leaflitter decomposition in soil.We found no effects of herbivore damage on the subsequent decomposition of leaf litter within any of the species tested. Our results suggest that leaf traits affecting herbivory are different from those influencing decomposition. Herbivore damage showed much higher intraspecific than inter-specific variability, while we observed the opposite for decomposition.Our findings support the idea that interactions between consumers and their resources are controlled by different factors for the green and the brown food-webs in tropical forests, where herbivory may not necessarily generate any direct positive or negative feedbacks for nutrient cycling.