Growth and branching habit of Eucalyptus nitens at different spacing and the effect on final crop selection

An experiment to investigate the effects of initial spacing on the growth, branching habit and form of Eucalyptus nitens (Deane et Maiden) was establi shed on a highly productive site at Upper Castra in northern Tasmania, Aust ralia, in 1992. The experiment covered stockings ranging from 500 to 1667 s tems ha(-)1 (SPH). At age 5 years there was competition within the stand an d significant impacts of stocking on tree growth. The degree of competition varied with stocking, indicated by green crown height which varied signifi cantly with stocking, ranging from nearly 5 m at 1500 SPH to 2.5 m at 500 S PH. Restriction of branch growth therefore occurred earlier at higher stock ings, however, tree diameter growth was also restricted by higher stocking. The mean dominant height (MDH) of the stand was 15.15 m at age 5 years wit h no difference between stockings. Total stand volume was significantly rel ated to stocking, higher stocking having higher volume. Forks and ramicorns were prevalent and 16% of all stems had forks and 44% had forks or ramicor ns. Below 1000 SPH the mean largest branch in the first 6 m log length was over 35 mm. The number of branches larger than 35 mm increased rapidly at l ower stockings. The trial was also evaluated for commercial thinning and se lection of 300 final crop stems suitable for pruning and growing to produce sawlogs or veneer logs. At age 5 years only 37% of stems met the requireme nt for selection for final crop. If branch criteria for final crop selectio n were included, 1000 SPH produced barely sufficient numbers of select stem s. The implications of stocking on stand management are discussed and initi al stockings of 1000-1100 SPH are recommended for E. nitens plantations. (C ) 1999 Elsevier Science B.V. All rights reserved.