CRB: Direct and Indirect Effects of Key Alien Species in Two Hawaiian Forest Communities

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9610413 Lorence A key issue in conservation and restoration biology is the role of invasive, alien species. Although the value of developing invasion ecology as a predictive science is increasingly recognized, this may be difficult unless manipulative experiments are used more frequently. In the proposed research, manipulative experiments will be used to analyze the effects of invasive species in a dry forest site on the Island of Hawaii where communities have long been noted for their disturbance prone features. The goal of the research is to determine how native Hawaiian communities change in response to the removal of alien species. Specifically, experiments will determine the regeneration potential of native species in disturbed and protected habitats. It is presumed that key alien species have a disproportionate effect on the distribution and abundance of native species in these forests. The experimental site will be located in the Kaupulehu Preserve on the island of Hawaii in an area where the alien, fire promoting fountain grass is now widespread. Recruitment of native and alien species following removal of fountain grass and control of rats will be monitored. Removal of fountain grass and control of rats is expected to result in an increase in recruitment of the native canopy, shrub, and herbaceous species. Secondary effects will also be investigated such as the invasion of other alien species suppressed by fountain grass, and increased levels of herbivory on native species as they increase in abundance. The extraordinarily high degree of endemism and endangerment of Hawaiian species is not justification for the proposed research; of more general significance is an increased understanding of the role of alien species in disruption of native plant communities, and the significance of primary and secondary effects. The apparent extreme susceptibility of Hawaiian plant communities to invasion by aliens should make it easier to see the consequences of removal of alien species. Lessons learned in the Hawaiian Islands about the role of alien species should have broad applicability to other plant communities.