Effect of diameter and plant spacing on growth of Acrocarpus fraxinifolius under mid hill conditions of Himachal Pradesh

The data were collected from randomly selected trees at three sites with plant spacing, viz. 1.5m x 1.5m, 1.0m x 3.5m and 3.0m x 3.0m (namely S-I, II and III, respectively) of Acrocarpus fraxinifolius (20 years old) in mid hill conditions of Himachal Pradesh. The effect of plant spacing and diameter class on growth characteristics, viz. diameter at breast height (dbh), tree height, bole height, form factor, basal area, stem volume and crown parameters was assessed. Stem volume was positively and highly correlated with all growth parameters and showed highest correlation (0.95) with dbh. The tree height, bole height, basal area, stem volume, crown height, crown width and crown area increased significantly with increase in diameter as well as with spacing. Study regarding fiber length and specific gravity also contributed to growth behaviour of pink cedar at different spacing, where, specific gravity of wood showed an erratic behaviour with slight variation from 0.66 to 0.88, while stem and branch fiber length increased (1.05 to 1.11mm and 0.78 to 0.95mm, respectively) with increasing plant spacing. The overall growth performance of the species was best at 3m x 3m spacing.