修枝对杉木节子发育和无节材比例的影响OA北大核心CSTPCD

This study investigates the influence of pruning on knot development and knot-free timber ratio in Chinese fir(Cunninghamia lanceolata).A 9-year-old Chinese fir plantation served as the research site,employing a randomized block design to establish pruning and non-pruning test treatments.Over nine years,the effects of pruning on knot development and knot-free timber ratio were examined.Standard wood methods were applied to sample nine Chinese fir trees subject to pruning and nine without pruning.Various techniques including sawing board,rotary cutting,and transverse and longitudinal section methods were employed to process the samples,with subsequent measurement of relevant indices.Analysis was conducted to ascertain differences in knot development and knot-free timber ratio between pruned and non-pruned trees.Results indicate a significant reduction in knot volume following pruning,with pruned Chinese fir demonstrating 48.70%and 34.44%lower knot volumes compared to non-pruned counterparts using the sawing board and rotary cutting methods,respectively.Furthermore,the impact of pruning on knot volume varied across different height sections,with the 0-2 m section experiencing the greatest reduction.Pruning also resulted in a notable increase in knot-free timber ratio within Chinese fir plantations,with pruned trees exhibiting 0.23%and 0.26%higher ratios compared to non-pruned trees using the sawing board and rotary cutting methods,respectively.Variations were observed in the determination of pruning effect indices using different methods,with the sawing board method emerging as a practical and effective approach for characterizing pruning effects in plantation settings.