Stripping of Acacia koa Bark by Rats on Hawaii and Maui

Abstract

Koa (Acacia koa) is the most valuable native timber species in Hawaii. Bark stripping of young trees by rats, a common but unstudied phenomenon, may affect survival, growth, and quality of koa. Up to 54% of the trees sampled in 4- to 6-year-old stands in the Laupahoehoe and Waiakea areas on Hawaii were wounded by rats; only 5% of trees sampled in a l-year-old stand on Borge Ridge, Maui, were wounded. Wounds were generally long and narrow. Complete girdling was not observed, and direct mortality seemed low. However, indirect effects of damage-deformation of stems, infection by pathogens, and premature death-require further study. Because only young trees seem susceptible to bark stripping, rodent control may be desirable during the first 5 years of koa stand growth.