紫椴生物量分配格局及异速生长方程

Biomass allocation patterns and allometric models of Tilia amurensis

紫椴是东北地区阔叶红松林中重要的阔叶树种,采用整株收获法分析39株紫椴地上、地下生物量分配格局。根据胸径(DBH)大小将紫椴划分为3个等级:小树(1 cm≤DBH<10 cm)、中树(10 cm≤DBH<20 cm)和大树(DBH≥20 cm)。以不同高度处树干直径作为自变量建立紫椴各器官生物量异速生长模型。结果显示:1)随着径级的增加,紫椴干、根生物量比例先增加后减小而树冠生物量比例先减小后增加,但不同径级间差异不显著;2)不同径级紫椴枝、叶生物量均位于树冠中下层;3)紫椴地上、地下生物量之间呈显著线性相关(P<0.001),拟合线性方程斜率为0.31;4)胸径和树高与地上竞争强度均呈显著的指数相关(P<0.001),地上竞争强度并没有影响树冠比例、茎叶比和根冠比,但与树高胸径比成幂相关(P<0.05);5)综合考虑模型的可解释量及回归系数显著性可知,胸径是预测紫椴不同器官生物量的最可靠变量。更准确地估测紫椴各器官生物量需要针对不同生长阶段或不同径级建立相应的生物量方程。

Tilia amurensis is an important broadleaved tree species in mixed broadleaved-Korean forests in northeastern China. In this study, the aboveand belowground biomass allocation patterns of T. amurensis were analyzed using 39 harvested trees with different diameters at the breast height （DBH）. And these trees were grouped into three size classes： small trees （1 cm≤DBH 〈 10 cm）, medium trees （10 cm ≤ DBH 〈 20 cm） and big trees （DBH ≥ 20 cm）. Allometric equations for different biomass components were developed by stem diameters （DBH ; tree base, DB ; 30 cm height, D30 and 1 m height, D100）. Our results showed that ： 1 ） the relative proportions of stem and root biomass increased gradually at the small-and medium-tree classes, and decreased gradually at the big tree class. The proportion of branch and leaf biomass was just opposite. But no significant difference was found among different treesize classes. 2） The branch and leaf biomass located mainly in middle and bottom layers of tree crown at each tree size category. 3 ）The aboveground biomass was significantly linearly correlated with belowground biomass （P 〈 0. 001 ）. The slope of the fitted linear model was 0.31. 4） Both DBH and tree height showed a significant exponential correlation with aboveground competition intensity（P 〈 0. 001 ）. There were no significant relationships between competition intensity and crown ratio, stem to foliage biomass ratio and root to shoot ratio （P 〉 0.05）. But the ratio of tree height to DBH exhibited a significant power relationship with competition intensity （ P 〈 0.05 ）. 5 ） According to the explainable variability and the significance of coefficients in allometric models, it can be concluded that DBH is a reliable variable for estimating the aboveand belowground biomass of T. arnurensis. Thus, the growth stage and tree size should be involved in allometry for precise estimation of above- and belowground component biomass.