Chemical and Kraft Pulping Properties of Young Eucalypt Trees Affected by Physiological Disorders

Abstract

This study evaluated how Eucalyptus physiological disorder (EPD) affects wood quality and pulping performance. Although research advances have been made in forest management and tree improvement programs for eucalypt plantations, some areas of Brazil are still subject to abiotic stress, mainly due to atypical climatic patterns. Tree growth is affected by abiotic stress, and this can change the wood properties, which influence the pulping process. The Eucalyptus trees used in this study were three-and-a-half-year-old hybrid clones. In order to evaluate the impact of physiological growth disorder on the wood, trees were selected with higher and lower levels of symptoms caused by EPD. First, the density, chemical composition, and variables of the pulping process of each of these woods were compared. The higher levels EPD symptoms resulted in poorer wood quality for pulping. To reduce the negative impact of the pulping process, reference woodchip samples from the industrial process were mixed with these wood samples and evaluated again. The results show that EPD negatively affected the wood quality required for pulp production when trees from higher stress conditions formed wood with more extractives (60% greater) and 9% more of lignin content. Thus, the amount of reagent used was increased and the pulp yield decreased. One solution to minimize the problem is to combine the woodchips from higher EPD trees and stands (20%) with non-EPD-affected chips (80%). Thus, it appears that affected wood requires special management attention in the context of pulp production.