Seed size and seedling ontogenetic stage as modulators of damage tolerance after simulated herbivory in a woody exotic species

Abstract

Herbivory is one of the most important threats that plants face during early stages of development. Previous studies have indicated that seed size and seedling ontogeny strongly influence the response to herbivory at the seedling stage. However, little is known about their interactive effect. We simulated herbivory on seedlings of the exotic Gleditsia triacanthos L. and evaluated the combined effects of seed size and ontogenetic stage at which herbivory occurred on tolerance to herbivory. A greenhouse experiment was performed, with three non-overlapping levels of seed size. Seedlings from each seed size were clipped at two ontogenetic stages (two and five leaves). After three weeks, seedling survival, height, leaf number and dry biomass were measured. Damaged seedlings were not able to reach the size of the undamaged ones. Seedlings from small seeds showed the lowest values in most of the growth variables. Seedlings cut at two-leaf stage showed a higher compensation capacity than those cut at five-leaf stage. Seedlings from large seeds cut at ontogenetic stage I showed the highest compensation capacity in most of the variables. Partly compensating herbivory at this stage may be an advantage for the expansion of this exotic species to new areas.