VEGETATION RESPONSE WITHIN EXCLOSURES IN HAWAI ' I : A REVIEW

Exclosure studies have been used to great advantage in the Hawaiian Islands to evaluate and demonstrate impacts of alien vertebrate herbivores upon native vegetation. Information presented for 50 exclosures, mostly on Hawaii and Maui, shows a wide range of vegetation responses. In most situations, native biota hold their own or increase following removal of vertebrate damage, but the chance of recovery becomes reduced as the extent of degradation increases. Displacement by alien grasses appears to be the most significant factor inhibiting reproduction of native species in areas other than rain forest. The intact native vegetation in "natural exclosures" shows that damage by alien vertebrates is a prerequisite for large-scale invasion of alien plant species. Priorities for the future include continuing maintenance and evaluation of existing exclosures and establishment of new ones in leeward low and middle elevation ecosystems. Comprehensive monitoring should be carried out to document biological and physical changes resulting from vertebrate herbivore exclusion aided by large fencing projects.