Dissertation Research: The Influence of Herbivory and Compensatory Regrowth on the Demography of Long-Lived Plants

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There has recently been considerable controversy over the ability of terrestrial plants to "compensate" for herbivore damage. If plants can effectively compensate for the tissue removal caused by herbivores, damage should have little influence on the population dynamics of plant species. Although several studies have looked at the influence of herbivory on semelparous (Flower only once) plants, little research has addressed the impact of herbivores on the lifetime offspring production of iteroparous (Flowering every year) species. An experiment will be performed in the Wrangell Mountains of Alaska examining the influence of chronic lepidopteran (Tortricidae) feeding on the growth, seed production, and seedling quality of dwarf fireweed, Epilobium latifolium, a long-lived herbaceous perennial. Plants will be subjected to three intensities of artificial damage over three years, giving data to construct probability transition matrices for growth and seed output. These models can then be used to estimate the influence of different frequencies and intensities of herbivory on plant performance over the thirty to forty year life-span of fireweed. An experiment in which compensatory regrowth following damage is controlled, in order to estimate the importance of regrowth in mitigating the impact of herbivory will be performed. This work will give one of the few estimates of the life-time impacts of herbivory on an iteroparous plant species.