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

非原生非洲草本植物已经入侵了夏威夷干燥森林的下层；它现在正在导致当地树苗死亡和成熟树木生产力下降。将这种生态系统完全转变为外来草原将导致高度生物多样性的丧失，自然生物地球化学循环的破坏，以及许多具有重要文化意义的植物的灭绝，但这些外来植物影响的机制尚不清楚。我们将确定草地如何改变本地树木对雨水的获取，以及这种影响如何转化为生产力的变化。将特别强调树木从小型暴雨中获得水分--这可能为较大事件之间的持续活动提供必要的水。未来的研究将调查对光和养分的资源竞争。我们的长期目标是全面了解导致生态系统功能转换和改变的机制。夏威夷的干燥森林有利于实现这一目标，其结果可能适用于其他旱地生态系统。

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.