RUI: Mechanisms Underlying Alien Grass Effects on Dry Forest Ecosystem Change - Changing Availability of Variable Water Sources

Csu Fullerton Auxiliary Services Corporation, Fullerton CA

Investigators

Abstract

Non-native African fountaingrass has invaded the understory of Hawaii's dry forest; it is now causing death of native tree seedlings and productivity decline in mature trees. Total conversion of this ecosystem to alien grassland would result in high biodiversity loss, disruption of natural biogeochemical cycles, and extinction of many culturally important plants, yet mechanisms underlying these alien-plant impacts are poorly understood. We will determine how fountaingrass alters native-tree access to rainwater, and how this impact translates into productivity changes. Particular emphasis will be placed on tree access to water from small rainstorms - which may provide water necessary for sustained activity between larger events. Future research will investigate resource competition for light and nutrients. Our long-term objective is a comprehensive understanding of mechanisms that cause conversion and alteration of ecosystem functions. The Hawaiian dry forest is conducive to this goal and results may be applicable to other aridland ecosystems.