天山林区六种灌木生物量的建模及其器官分配的适应性

灌木全株生物量估算模型的构建仍存在一定困难,对灌木生物量在器官分配上所体现的适应性研究也不够充分。以天山林区6种常见灌木为研究对象,在天山的东段、中段、西段林区分别设置样地进行群落调查,由此以全株收获法取得6种常见灌木若干标准株的全株、根、枝、叶及各径级根的生物量,将D~2H(地径平方与高度的乘积)与V(冠幅面积与高度的乘积)分别选为估测模型的自变量,通过回归分析法建立了各种灌木全株生物量的最优估算模型,然后比较了此6种灌木全株生物量在营养器官上分配差异以及根系生物量在径级上的分配差异。结果表明:(1)天山林区6种常见灌木中,小檗(Berberis heteropoda Schrenk)、忍冬(Lonicera hispida Pall.ex Roem.et Schuet.)、栒子(Cotoneaster melanocarpus Lodd.)的全株生物量约为8.48—9.01 kg,蔷薇(Rosa spinosissima L.)、绣线菊(Spiraea hypericifolia L.)、方枝柏(Juniperus pseudosabina Fisch.et Mey.)的全株生物量约为2.71—3.20 kg;(2)蔷薇、绣线菊、栒子的全株生物量最优估测模型是以V为自变量的函数,小檗、忍冬、方枝柏的全株生物量最优估测模型是以D~2H为自变量的函数,各模型R~2值均在0.850以上,且在P0.05水平上达到显著,模型模拟结果达到了较高的准确度;(3)6种灌木全株生物量在根、枝上的分配比重差异不显著,仅在叶上的分配比重有差异(P0.05);根系生物量在径级上的分配均呈现随根系径级下降而减少的规律,6种灌木在径级大于2 mm根上的分配比重存在差异(P0.05,径级大于20 mm根为P0.01水平);(4)6种灌木全株生物量在营养器官上的分配差异以及根系生物量在径级上的分配差异均体现了各物种对其生境选择的适应策略。

Biomass estimation modeling and adaptability analysis of organ allocation in six common shrub species in Tianshan Mountains forests, China

Estimation modeling of the total biomass of shrubs is associated with certain difficulties. Moreover, merely studying the effect of organ allocation adaptability on shrub biomass is not sufficient. Thus, to investigate the effectiveness of biomass estimation modeling on organ allocation in plants, we focused on six common shrub species found in the forests of Tianshan Mountains, northwest China. To conduct a community investigation, we selected three sample areas in the eastern, central, and western regions of Tianshan Mountains. A number of whole standard plants from six shrub species were harvested to determine total biomass, which was divided into the, biomass of the roots, branches, and leaves, along with different classes of root diameter. D²H (the square of the diameter multiplied by height) and V (the area of the crown multiplied by height) were selected as the independent variables in the estimation models. Optimal estimation models for the total biomass of the six shrub species were constructed using regression analysis. These models were used to compare differences in total biomass allocation to vegetative organs and in biomass allocation to roots of each root diameter class in the shrub species. The following results were obtained. First, the total biomass of Berberis heteropoda, Lonicera hispida, and Cotoneaster melanocarpus was approximately 8.48 to 9.01 kg, whereas that of Rosa spinosissima, Spiraea hypericifolia, and Juniperus pseudosabina was approximately 2.71 to 3.20 kg. Second, the optimal estimation models for the total biomass of R. spinosissima, S. hypericifolia, and C. melanocarpus were functions based on V as an independent variable, whereas those for B. heteropoda, L. hispida, and J. pseudosabina were functions based on D²H as an independent variable. The value of R² for each estimation model was greater than 0.850, and all the models reached a high degree of accuracy at the 0.05 significance level. Third, differences in the proportional allocation of total biomass to roots and branches of the six shrub species were not significant, whereas that to leaves was significant at the 0.05 significance level. The root biomass of all six shrub species decreased with decreasing root diameter class, with significant differences in the proportional allocation of biomass to roots in roots with a diameter greater than 2 mm (significant at the 0.05 and 0.01 significance levels for roots with diameters greater than 20 mm). For all examined shrub species, we conclude that the differences in total biomass allocation to vegetative organs and in biomass allocation to the roots of each diameter class reflect adaptive strategies to their respective habitats.