应用相对生长法对不同密度华北沙地小黑杨人工林生物量及其分配规律进行研究。结果表明,用模型W=aDb估测的27年生1000、500和250株·hm-2的小黑杨林分生物量分别为85.23、102.60和86.74t·hm-2;29年生小黑杨林分生物量分别为88.64、104.90和90.94t·hm-2。林分生物量与林分的密度和年龄密切相关,呈现出随着密度增加而先增加后减少、随着林龄增加而增加的规律。密度对小黑杨器官间生物量分配有重要影响。密度不同,器官生物量所占比例不同,其中,叶和皮生物量所占比例均随着密度增加而增加,干、枝和根生物量所占比例随密度增加没有表现出明显规律性。在3种密度中,干生物量所占比例最大,叶生物量所占比例最小。3种密度小黑杨林分生物量的径阶分配呈正态分布,在1000株·hm-2的小黑杨林分中72.37%的生物量集中在18～22cm的径阶范围内;500株·hm-2小黑杨林分中生物量主要集中在20～26cm的径阶范围内,占总生物量的90.02%;250株·hm-2的小黑杨林分中,生物量主要集中在26～30cm的径阶范围内,占总生物量的68.27%。
The biomass and distribution of Populus×xiaohei plantation with different stand densities and ages were studied by the methods of sampling permanent plot and allometric dimension analysis in sand land of North China. The biomass of plantation with densities of 1 000,500 and 250 tree5hm-2 was measured by the model of W=aDb. The biomass of 27 years old P.×xiaohei plantations was 85.23,102.60 and 86.74 t·hm-2 ,respectively; While the biomass of 29 years old P.×xiaohei plantations was 88.64,104.90 and 90.94 t·hm-2 ,respectively. Stand biomass had a close correlation with the stand density and the age. It first increased then reduced along with the increase of stand density, but increased along with the increase of stand age. Stand density had the important influence to the biomass distribution of the P.×xiaohei organs. The stand density different, the proportion of the organ biomass was different. The proportion of leaf and bark biomass increased along with the increase of stand density, but the proportion of stem, branch and root biomass did not display the obvious regularity along with the increase of stand density. In the three densities of plantations, the proportion of stem biomass was the most, the leaf the least. The biomass distribution of three densities of plantations assumed the normal probability distribution.In plantation with density of 1 000 tree·hm-2, 72.37 per cent of biomass centralized on diameter classes from 18 to 22 cm. 90.02 per cent of biomass centralized on classes from 20 to 26 cm in plantations with density of 500 tree·hm-2; In plantation with density of 250 tree·hm-2, 68.27 per cent of biomass centralized on classes from 26 to 30 cm.
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