Wood Quality of Old-Growth Koa Logs and Lumber

Acacia koa trees are ecologically, economically, and culturally significant to the Hawaiian Islands. Koa wood is one of the most valuable species in the world and sale of koa products represents a majority of all the Hawaiian wood products sold by Hawaiian retailers. Today, there is concern in Hawaii among foresters, forest landowners and managers, wood products manufacturers, and the public that the remaining old-growth koa resource has become scarce, is suffering from declining health and diseases, and is characterized by poor growth form. Current practices require harvest of only dead and dying trees and using downed material in wood products manufacturing. We examined lumber volume and value recovery from logs sawn from dead and dying trees and from relic logs (logs that have been on the ground) from four sites on the island of Hawaii. Gross lumber recovery from all study logs was 71 percent. Log size did not significantly influence lumber volume recovery. Forty-five percent of the lumber manufactured from relic logs was below grade compared with 26 percent of the lumber sawn from standing dead and dying trees. Variables that affect lumber quality, such as different defects and heartwood proportion, were measured. Decay-type defects were the most prominent.