Evolution of Acacia koa on the Hawaiian Islands

Abstract

Acacia koa (koa), a leguminous timber wood tree, has a significant importance in the economy, ecology, and culture of Hawai'i. Natural A. koa forests have been gradually disappearing over 100 years due to ranching and an infestation by the Fusarium wilt disease. Recently, there has been a growing interest for reestablishment of A. koa in Hawai'i to create more profitable, ecologically sound, sustainable land-use systems. For successful development of agroforestry areas with wilt-free and high wood-quality A. koa trees, it is important to have a better understanding and awareness of the nature of the plant. This report presents a review of the current knowledge on A. koa, including its roles as an agroforestry tree, botanical characteristics, genetic diversities, propagation methods, and evolution.