EFFECTS OF SPACING AND PRUNING ON GROWTH RATE AND YIELD OF EUCALYPTUS CAMALDULENSIS DEHNH. PLANTATIONS

Abstract

Studies on the effects of 3 planted spacing (2 x 2, 2 x 4 and 2 x 8 m) and 2 pruning levels of 3 and 5 m aboveground with a control by a split-plot in Randomized Block Design with three replications in Somdet plantation, Somdet district, Kalasin province were carried out in 3-ycar old stands of Eucalyptus camaldulensis and their effects at 4-year old (after 1 year of pruning) were followed up in terms of relative growth rates of diameter at breast height, total tree height, mean biomass production of stem, branch, Ieaf and aboveground and total biomass yield of each part of trees in stands. Analyses of variance of all values of relative growth rate showed significant difference among means at P>0.100 due to the two treatments applied and there was an interaction between the two treatments for the mean relative growth rate of DBH but non-interaction for other growth parameters. Mean relative growth rates of DBH of 2 x 2 m planting space with 3 m pruning level or control plots were equally largest but those of 2 x 4 m planting space was highest in 3 m pruning level plot with the control plot was the next and lowest in 5 m pruning level plot. In 2 x 8 m planting space, this rate was equivalently high in control plot and in 5 m pruning level plot whilst it showed a similar high rate as in 3 m pruning level plot. Mean relative growth rate of total tree height was found to be equally high in 2 x 8 m and 2 x 4 m planting space plots but in 2 x 4 m planting space plot, it was as high as in 2 x 2 m planting space plot. The effects of planting space on mean relative biomass production of stem, leaf and aboveground was equally high in 2 x 8 m and 2 x4 m planting space plots but in 2 x 4 m and 2 x 2 m planting space plots were not significantly different except for this rate for Ieaf which showed non-significant difference. The effects of pruning level on this rate in every tree part and in the aboveground part were significantly different and they were higher in the control and 3 m pruning level plots than in the 5 m pruning level plot The effects of planting spaces and pruning levels on mean biomass production followed well with the theory of C-D effects partitioned into levels of pruning and control. Effects of both treatments on the relative production rate of total biomass yield were found to be in similar trend as for the mean biomass production but the effect of planting space was differently pronounced only for stem, leaf and total aboveground yields but it was not statistically different for branch yield, However, 3 m pruning level showed a tendency of biomass yield improvement more than in the control and 5 m pruning level plots. The effects of these two treatments on total biomass yields were found to be well fitted to the theory of Y-D effects separately to the levels of pruning and control and the stand with high planting density (closed-space) and slight pruning might in duce a large total biomass yield.