西藏米拉山白桦种群生物量和生长量研究

在区域样地调查基础上，通过解析木分析，比较了不同坡向、不同海拔的白桦种群生物量和生长量．结果表明，米拉山白桦种群的生产量约在363．1～2072．94kg·hm^-2·年^-1之间；各种群的现存生物量在7625．00-33167．00kg·hm^-2之间，种群间生物量差异显著．砍伐后的白桦萌生木、生物量和生长量均小于实生木。并且在生长过程中出现早衰的现象，表明人类活动的干扰对白桦种群有较大影响．米拉山东、西坡不同海拔生境条件下，水分地带性的变化对白桦各器官内的水分分配以及生物量组成没有显著影响．

Biomass and yield of Betula platyphylla population in Mila Mount of Tibet

Mila Mount in Southeast Tibet is the west boundary of the horizontal distribution of Betula platyphylla. It is also the highest altitude area in China and the world, where Betula platyphylla is distributed. Based on the investigation of regional sample plots and the analysis of analytic trees, this paper compared the biomass and yield of Betula platyphylla population at different slope orientation and different altitude. The results showed that the growth of Betula platyphylla was greatly interfered by human activities. The yearly productivity of Betula platyphylla grown in Mila Mount was 363.1-2,072.94 kg x hm(-2), and the biomass was 7,625.00-33,167.00 kg x hm(-2), indicating that the biomass of Betula platyphylla was quite different for different population. The productivity and biomass of Betula platyphylla coppice after cutting were lower than those of seedling forest, and there existed youth broken-down in the coppice. The zonal changes of water resources had no significant effect on the water allocation and the biomass of Betula platyphylla.