Himalayan blackberry (Rubus armenicus) and English ivy (Hedera helix) response to high intensity-short duration goat browsing.

摘要

The goal of this dissertation is to examine the effectiveness of high intensity-short duration goat browsing for the control of Himalayan blackberry (Rubus armeniacus) and English ivy (Hedera helix ), two widespread noxious weeds in the Pacific Northwest.;The effects of goat browsing on Himalayan blackberry vigor, as quantified by densities of different age class stems, are compared to mowing and goat browsing followed by mowing over a period of three years. Although total stem density and node density declined, primocane density increased after all types of treatment. This indicates that the population was still vigorous. Recruitment of new plants was reflected by an increase in seedling density. Changes in percent cover of vegetation functional groups were also examined. All three treatments produced a decline in Himalayan blackberry cover and an increase in perennial grass cover, though differences among treatment types were not significant. Perennial forb cover increased as a result of all treatment types.;English ivy was successfully controlled by goat browsing as quantified by percent cover. Two years of browsing reduced percent cover more than one year of browsing. Both levels of browsing produced results that were significantly different when compared to the untreated control indicating that repeated high intensity-short duration browsing is justified for control of this invasive plant species.;Differences in response of these two invasive, creeping perennials are attributed to differences in species growth rates, location of meristematic tissue in stolons vs. rhizomes and shade conditions at the research sites.