Twenty-five ungulate exclosures were established in Olympic National Park and Olympic National Forest in the 1930's and 1950's. Information from earlier studies and resampled vegetation (where possible), within and adjoining exclosures from 1987-1990, were used to describe effects of ungulates on forest vegetation. In communities initially dominated by grasses or grasslike plants on valley floors, exclusion of ungulates resulted in decreased cover of grasses and forbs, decreased species richness of forbs, and sometimes increased height and abundance of ferns. Shrub size and density increased following exclusion, particularly salmonberry (Rubus spectabilis) and huckleberry (Vaccinium spp.). Browsing appeared to affect recruitment of Pacific silver fir and western red cedar following clearcut logging, but effects on other species were unclear. Results support the general conclusion that the extent to which herbivores can cause changes in forest ecosystem processes may depend on the scales of other disturbances.
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