不同林分密度油松人工林生物量分配模式

Biomass allocation in relation to stand density in Pinus tabuliformis plantation

为了解不同林分密度下各组分生物量分配模式的变化特征,以20年生油松（Pinus tabuliformis）人工林为研究对象,采用嵌套式回归法建立了油松各器官生物量与胸径、树高的回归方程,并分析了林分地上和地下各器官生物量比例随林分密度的变化趋势。结果表明：油松林生物量分配格局因林分密度（267~3 367株/hm2）的不同存在较大的差异。地上、地下生物量范围分别介于20.74~141.25 t/hm2和5.36~36.92 t/hm2之间。生物量根冠比随林分密度的增加而增加（0.223~0.313,平均0？？276）,其中树干和枝条占总生物量的比例随林分密度的增加而减小,而叶片、粗根和细根的比例随林分密度的增加而增大。研究结果在一定程度上检验了最优分配理论的适用性,同时油松根系生物量模型以及估算方法对准确估算森林生态系统生物量及碳循环具有借鉴价值。

The biomass allocation pattern is critical for understanding individual growth processes and modelingterrestrial ecosystem carbon cycles in the context of global climate change. Our objective was to determine the effects ofstand density on biomass allocation pattern in aPinus tabuliformisplantation in Beijing, China. Eighteen sample trees foraboveground components and eleven sample trees for belowground components were used for developing DBH-biomassmodels by the nested regression method. Thirty-three temporary plots（20 m×30 m） with different stand densities（267-3 367 trees/ hm2） were investigated by recording DBH of all trees over 5 cm DBH in July—August 2012. Allcomponents exhibited significant variations across the surveyed plots with different stand densities. Above and belowground biomass ranged from 20.74 to 141.25 t/ hm2 and 5.36 to 36.92 t/ hm2, respectively. The average biomass ratio ofroot to shoot was 0.276, and increased from 0.223 to 0.313 as stands becoming denser. In addition, with increasing standdensity, the proportion of stem and branch to total forest biomass decreased, while foliage, fine root and coarse root bio-mass increased. The functional balance theory is tested in part by our results, which were also improtant for accurate es-timation of ecosystem biomass and carbon accounting.