Stimulating growth of stagnated Acacia koa by thinning and fertilizing

Abstract

Building Acacia koa, Hawaii's most marketable native tree, into a viable resource is economically and eco1ogically desirable. But little is known about natural stand development and management of this scarce resource. Therefore, the effect of thinning, fertilizing, or both on short-term growth and survival was studied in a stagnated 12-year-old koa stand on Kaleakala, Maui. Mean relative basal area growth rates (RGR) for the period 1975-77 ranged from 6.7 percent per year for control trees to 10.0 percent per year for thinned-fertilized trees. Both thinned and thinned-fertilized trees grew significantly faster than control trees. An unplanned, complete defoliation of all trees occurred in the study area in January 1977. RGR's after defoliation were significantly smaller than rates before defoliation for ail treatments. Differences among treatments after defoliation were not significant. Survival in 1978 ranged from 51 to 73 percent and was not significantly different among treatments.

Citation

Scowcroft, Paul G.; Stein, John D. 1986. Stimulating growth of stagnated Acacia koa by thinning and fertilizing. Res. Note PSW-RN-380. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 8 p.