Research Of Larch Plantations Pruning

This search aims at the pruning question on the Larch plantation, according to the data that that comes from the field survey involved 95 sample trees in 19 plots of the Menglianggu forest in Jiamusi, Heilongjiang province in 2007 and 2008. Based on the investigations of larch (Larix gmelinii) plantations with different ages, including knots of 50 sample trees in 10 plots and disks of 95 sample trees in 19 plots, the affect of the stand of forest age, density, average tree height (or site quality) on crown length and the rate of crown length were analyzed, models of tree height, effective crown height and dead branch's height were established, and combination of the three models, decided the plan and built the pruning model.According to the scatter plots of stand age and height of disk data of Mengjiagang, this paper devised a candidate model of stand height curve, and established stand height curves. RBC could reflect information of age when the branches stop growing, RBD could reflect information of branch lifetime and height of knots, according to that, scatter diagram of AKC and Hec, and scatter diagram of AKD and dead arm height have been established respectively. The scatter diagrams show that Hec increases with AKC, and presents power function curve obviously; AKD increases with dead arm height, and also presents power function curve obviously. Exported effective prediction model of crown height and candidate prediction model of under-branch height, and fitted curve respectively. The fitting precisions are 0.91,0.85 and 0.86; forecast precisions are 98.5%,98.4%and 98.3%.Both of the two models resulted in good fit effect.Through the research of Larix olgensis plantations stand pruning model, when the stand age reached to 14 years (after the stand closed) start the first prune. With the forest aging, the pruning interval increased at first and then decreased, and so did the pruning strength. It reflects the variation of crown in different growing seasons.Stands with different densities have huge gaps on pruning interval and pruning strength, Stand density impacts pruning strength variable and pruning interval variable of pruning model. While the stand density increase, the pruning interval gets shorter and the pruning strength gets lower. Starting time of pruning is independent of stand density.