Forest growth along a rainfall gradient in Hawaii: Acacia koa stand structure, productivity, foliar nutrients, and water- and nutrient-use efficiencies.

We tested whether variation in growth of native koa (Acacia koa) forest along a rainfall gradient was attributable to differences in leaf area index (LAI) or to differences in physiological performance per unit of leaf area. Koa stands were studied on western Kauai prior to Hurricane Iniki, and ranged from 500 to 1130 m elevation and from 850 to 1800 mm annual precipitation. Koa stands along the gradient had basal area ranging from 8 to 42 m/ha, LAI ranging from 1.