桤柏混交林种群生物量动态与密度调节

研究了四川省盐亭县桤柏混交林中桤木和柏木种群的生物量动态、密度动态及 种群密度对生物量动态的调节．结果表明，桤木种群生物量在１８ ａ内符合逻辑斯蒂增长， 柏木种群生物量在２０ ａ内呈幂函数增长．而种群密度在 １８ ａ内均呈负幂函数降低在桤 柏混交林中．密度制约是决定种群生物量动态的主要因素，棺木和柏本平均单株生物量较 符合Ｙｏｄａ提出的－３／２自疏定律为快，其自疏系数分别为一２．３３和一３．９７．个体平均生 物量的增长比由密度下降引起的生物量降低快，因此，两种群生物量在密度调节过程中仍 然保持增长状态．其中柏木是生物量增长旺盛的种群．

Dynamics of population biomass and its density-density-dependent regulation in alder and cypress mixed forest

The biomass dynamics, density dynamics, and density-dependent regulation of biomass dynamics in alder and cypress mixed forest were studied at Yangting County of Sichuan Province. The results show that the biomass of alder accords with logistic growth in the past 18 years. and that of cypress conforms to power function growth in tile Past 20 years. The densities of alder and cypress show a negative power function growth in the past 18 years. In the mixed forest, density-dependent death is tile key factor determining the dynamic, of population biomass. The mean individual biomass is approximately related to the density by the - 3/2 power law, and the self-thinning indices of alder and cypress are - 2. 33 and - 3. 97, respectively. The increase in mean individual biomass is greater than its decrease caused by population density reduction. As a result, the biomass of the two populations still increases during the period of density- dependent regulation, and the biomass of cypress population increases more vigorously.