基于节子剖析数据的长白落叶松人工林枝条丢失年轮数研究

Number of missing-rings in branch of Larix olgensis plantation based on knots’ section data analysis

【目的】为提高木材质量,本文利用节子剖析数据建立枝条丢失年轮数量的混合效应模型,以达到预测枝条丢失年轮数量的作用,为人工整枝提供一定的理论依据。【方法】以黑龙江省孟家岗林场长白落叶松人工林为研究对象,基于50棵长白落叶松解析木的1 434个节子数据,以Poisson分布为基础,采用SAS9.4软件中的glimmix模块,建立了节子丢失年轮数量的广义线性混合模型,通过计算相应的指标,选出最优混合模型。【结果】在考虑树木效应情况下,包含截距、节子高度、节子相对高度的随机效应参数的混合模型为最优混合效应模型;在考虑等级效应的情况下,包含节子相对位置、节子直径的随机参数的混合模型为最优混合效应模型。综合比较,两个混合模型的拟合效果均好于基础模型,其中考虑树木效应的拟合效果最好。模型的拟合结果表明:节子丢失年轮数量与节子着生高度、节子直径密切相关,位于树干基部的直径较大的节子,由于竞争作用,生长受到抑制,但是生存能力强、存活时间长,故而产生丢失年轮的数量较多。着生位置越靠上的节子,生存条件好,产生丢失年轮的数量少。【结论】通过长白落叶松人工林节子丢失年轮数量混合模型的建立,并对模型的预测效果进行检验,检验结果显示本文的混合模型能对枝条丢失年轮的数量进行预测且偏差较小。在接下来的研究中可以进一步完善,从而为人工整枝提供一定的理论依据。

[Objective] To improve the quality of wood, the mixed effect model of the number of missingrings was established based on knot analysis data in order to predict the number of missing-rings and provide a theoretical basis for artificial pruning. [Method] In this paper, the Larix olgensis plantation in Mengjiagang Forest Farm of Heilongjiang Province of northeastern China was used as the research object.Using 1 434 knot data of 50 Larix olgensis trees, based on the Poisson distribution, the glimmix module in SAS9.4 software was used to establish the generalized linear mixed model of the number of missing-rings in the knot. The best hybrid model was selected by calculating the corresponding indicators.[Result] Considering the tree effects, the optimal mixed effect model is a model that adds the random effect parameters to the intercept, knot height and knot relative height. Considering the rank effect, the optimal mixed effect model is a model that adds random effect parameters to the knot relative height and the diameter of the knot. Comprehensive comparison showed that the fitting effect of the two hybrid models was better than the basic model, and the fitting effect of considering the tree effect was the best. The fitting results of the model showed that the number of missing-rings was closely related to the height of the knot and the diameter of the knot. The knots with lower position and larger diameter were inhibited by competition, but the survival ability was strong, so the number of missing-rings was large. The higher the birth position of the knot is, the better the living condition is, and the less the number of missing-rings is.[Conclusion] Through the establishment of the mixed model of the number of missing-rings in the Larix olgensis plantation, the prediction effect of the model is tested. The test results show that the hybrid model can predict the number of missing-rings and the deviation is small. In the next study, it can be further improved to provide a theoretical basis for artificial pruning.