Predicting Models Of Knot Distribution And Properties For Mongolian Scots Pine Plantation

Based on the data of stem analysis, branch analysis, and knot characteristics from 61 sample trees in 12 sample plots for Mongolian pine plantations with different age, different stand density, spatial distribution of the knot under different forest conditions were discussed in this paper, knots in different sizes of tree was studied to evaluate the effect that knot size and distribution impact on timber quality, knot dynamic models were developed using stand and tree variables. The size and rule of knot on different deveolopment phases were analyzed. The study in the paper determine proper pruning height, control dead branch and knot size along the stem and improve timber quality. The results are followed:(1) Knot vertical distribution is that the knot number is gradually decreased with adding hieght of knot,but the tendency is not distinctness, the knots obey uniform distribution in horizontal direction.Based on the theory growth equation, including knot frequence, angle, diameter and length, were developed from tree attributes and stand variables by using the nonlinear regression model.the variety rule of knot diameter and length were analyzed in defferent tree and stand condition.(2) The development phases of knots: from the birth of a branch to its growth, cessation (BC), from growth cessation to death (CD), form death to occlusion (DO).Branch formed visible annual rings for 8 years on the average (BC), the time period that branches remain alive without visible annual ring production(CD) was 5 yeas on average and it accounted for 38% of average lifetime of the branches. The time period from the death of a branch to its occlusion averaged 13 years. The numbers of annual rings as well as the stem width of respective zones were used as dependent variables predicted by models expressed as function of tree variables and knot attributes. The rule of the time period that branches remain alive without visible annual ring production were emphase to study in this paper, the methods of logical prunning were studied to improve lumber quailty.These results can provide theory base and management method for improving forest increment and timber quality which is of great significance.