Among-tree variation in leaf traits and herbivore attacks in a deciduous oak, Quercus dentata

Abstract

Variations in defensive and some other leaf traits were studied in a population of an oak species, Quercus dentata Thunberg, in northern Japan, with reference to attacks by ectophagous herbivores and leafminers. The oak population showed substantial individual variations in concentrations of total phenolics and condensed tannins, nitrogen content, trichome density, leaf area and budburst timing. With the exception of leaf mass per area, which showed a positive relation with leaf toughness and a negative relation with water content, no significant relation was observed between the plant traits studied, suggesting an absence of trade-off or linkage between them. The oaks also showed substantial individual variations in leaf area loss by ectophagous herbivores, densities of major leafminers (Phyllonorycter and Stigmella species) and survival of Phyllonorycter sap-feeding larvae. The density of trichomes showed a significant, negative relation with leaf area loss by ectophagous herbivores, but significant, positive relations with densities of some leafminers. The other leaf traits seldom showed significant relations with herbivore densities or survival. In this oak population, these traits may not have enough variations to be reflected in the abundance and performance of herbivores.