PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Are plant leaves less susceptible to herbivory less decomposable?: a study from Bornean forests in Malaysia.

Kurokawa, Hiroko^{*,1, 2}, Nakashizuka, Tohru², ¹ Kyoto University, Otsu, Shiga, Japan² Research Institute for Humanity and Nature, Kyoto, Kyoto, Japan

ABSTRACT- It has been suggested that plant leaves less susceptible to herbivory are less decomposable, because leaf characteristics inhibiting herbivory can also reduce decomposer performances. We tested this suggestion using 40 tropical trees in Borneo, Malaysia. The tree species cover much of the leaf characteristics and taxa occurring in the Bornean forests. We examined leaf performances and characteristics. Leaf performances we measured include herbivory rates, decomposition rates, and leaf life spans. Leaf characteristics we measured include the concentrations of total phenolics, condensed tannins, lignins, nitrogen, and carbon, leaf toughness, and LMA. We first explored, with all species combined, Pearson's correlation among their leaf performances and characteristics. We did not find any significant correlation among the herbivory rates, decomposition rates, and leaf life spans. We found significant correlations of the decomposition rates with a set of the leaf characteristics. In particular, the correlations with the lignin concentration and LMA were strong. On the other hand, we found no significant correlation of the herbivory rates and leaf life spans with any leaf characteristics. Next we explored correlations within separate families. Within families having little variation in the lignin concentration and LMA and thus showing no correlation between these characteristics and their decomposition rates, some families showed significant correlation of their decomposition rates with the concentrations of condensed tannins or total phenolics. Moreover, the herbivory rates of some families correlated with the concentrations of condensed tannins or total phenolics. Based on these results, we argue that the anti-herbivory strategies of the Bornean plant species are highly species-specific and there is no singular leaf characteristic that can explain the various types of anti-herbivory strategies adopted by different species. By contrast, the decomposition rates of these species' leaves are determined, regardless of species identity, by a set of leaf characteristics including their lignin concentrations and LMA. Thus, we conclude that more defensive leaves are not necessarily less decomposable in the Bornean forest ecosystems.

Key words: herbivory, decomposition, phenolic compounds, tropical forests