Effects of herbivore-bearing adult trees of the oak Quercus crispula on the survival of their seedlings

The acorn-producing oak Quercus crispula Blume is shade-tolerant and its seedlings were found to be underdispersed on the forest floor, forming seedling aggregations near fertile canopy trees. However, 84.4% of the seedlings were dead within 2 years, with the highest mortality near the adult canopy trees of Q. crispula. This was mostly due to the high levels of herbivory by lepidopteran larvae. The most serious damage was caused by spring consumers, which fed on the leaves of canopy trees in June and, when the food quality of the leaves declined, fell down to the forest floor to consume the juveniles, including the seedlings. Contrary to the expectation of the herbivore-host arms race theory, most of the herbivores were polyphagous. The most dominant spring consumer Telorta edentata (Leech) was also polyphagous, and its distribution on the forest floor showed a high level of association with the distribution of dead oak seedlings.