Growth characteristics in diameter, height, and volume of a Eucalyptus nitens plantation with different silvicultural treatment for pruning and thinning

Abstract

Chile has an important tree cover of Eucalyptus nitens (Deane and Maiden) plantations destined primarily for pulpwood production. Nevertheless, other products such as sawlogs and veneers are required because of the continually changing market for wood, as well as the need to obtain greater economic returns from the forest plantations. The present work describes the results obtained in a trial of pruning and thinning of Eucalyptus nitens plantations during eight years of control. The trial was established in 1989 and was located close to Los Alamos, Eighth Region, Chile, and involved observing an arrangement of two factors: intensity of thinning (without thinning, and thinning to 800 and 400 trees ha–1) and severity of pruning (without pruning, and pruning at 3.5 and 7.0 m), and three replications. Three measurements were taken: at the establishment of the trial, in October 1995 (6 years old), in October 1999 (10 years old), and in 2003 (14 years old). The diameter at breast height (dbh) was measured for all the trees of the plots, and the total height in a subsample of 15 trees per plot. After eight years of growth, the plots most intensely thinned reached the greatest tree growth in diameter and volume. Thinning has a significant effect in growth, but not pruning. Growth in diameter, height, and volume by tree of the 400 trees per hectare of greater dbh did not vary significantly with the treatment. The greatest volume per hectare was gained with 1100 trees ha–1 and 3.5 m pruning, with 680.0 m3 ha–1 and a mean annual increment (MAI) of 48.6 m3 ha–1 year–1.