Liberation: Acceptable production of tropical forest timber

Reduced impact logging in an eastern Amazonian terra firme forest left more than half of the next crop trees growing at a rate corresponding to a rotation of more than a century to attain 60-cm dbh. Two years after the logging, in 20 ha of the logged forest, tree competitors around crop trees were eliminated. Competitors were defined as trees whose crowns overtopped crop trees, those within 2 m of them, and trees as tall as or taller than the crop trees closer than indicated by a basal area of 15-25 m(2)/ha, depending on their summed diameters. During the subsequent 5.7 years, increment of the liberated crop trees was 20% greater than that of comparable crop trees left in another 20 ha of the same logged forest without liberation. Had the competing trees been identified at the time of the logging the 5.8/ha that were merchantable could have increased the yield from 25 m(3)/ha to as much as 43 m(3)/ha. This added harvest should have more than paid the entire cost of the liberation, including the elimination of the remaining unmerchantable, trees. Additionally, a prospective reduction of 25% in the wait for the next harvest, as compared with logging only, would have been created. Where the economical sustainability of tropical wood productivity and quality is a goal, the wisdom of neglect of liberation is questioned. (c) 2006 Elsevier B.V. All rights reserved.