Defoliation by insects reduces the wood quality and cellulosic pulp production

Abstract

Abstract Defoliating insects damage forest plantations, but the estimation of their losses does not take into account wood quality changes. The objective was to evaluate the wood quality and pulp production of two clones of Eucalyptus grandis × Eucalyptus urophylla (clone A) and Eucalyptus saligna (clone B) damaged or not by defoliating insects. Five healthy trees and five attacked by Gonipterus platensis Marelli (Coleoptera: Curculionidae) were selected per clone. The wood volume per hectare in the affected settlements was at least 9% lower and damaged trees showed lower wood basic density, with at least 4.6%. The lignin and extractive content in the wood increased by at least 5.6 and 45%, respectively, while the syringyl/guaiacyl (S/G) ratio remained constant for clone A and increased 10% for clone B. For pulps, an increased effective alkali and decreased pulp yield were experienced for both clones while bleaching or pulp quality was not affected. In the stands affected by defoliating insects, productivity was 9 and 19% lower considering the wood volume per hectare and 15 and 24% considering the cellulose pulp production per hectare, respectively.