中低强度间伐对杆材阶段马尾松林生物量的影响

Impact of Intermediate Thinning on the Biomass Dynamic in Masson Pine Stands with Variant Densities

对杆材阶段不同密度的马尾松林在低强度间伐后生物量的动态变化进行了分析对比 ,结果表明 :间伐后平均木的单株生物量和各器官生物量随密度增加而减少 ;随林分年龄的增加 ,单株生物量与树干、皮、根的生物量因积累而增大 ,但枝、叶的生物量先增加后减少 ,在林分年龄为 2 0 a时达到最大值 ,随后又接近间伐前的数值 ;林分生物量随年龄增加而增加 ,其中密度为 30 0 0株·hm- 2 的林分生物量始终最大 ,密度为 375 0、2 6 5 5株· hm- 2 的林分次之 ,密度为 45 15株· hm- 2 林分最小 ;间伐后不同密度马尾松林生物量生长量变化情况不同 ,密度为 2 6 5 5株· hm- 2的林分没有出现最大值 ,密度为 30 0 0和 375 0株· hm- 2的林分在林龄为 2 0a时出现最大值 ,密度为 45 15株· hm- 2的林分在林龄为 17a时出现最大值 ,说明林分密度过大会影响林分生长 ,应采取间伐措施调节林分密度 ,密度为 30 0 0和 375 0株· hm- 2 的林分第二次间伐时间可选在林分年龄为 2 0 a,而密度为 45 15株· hm- 2 的林分应选在林龄为

The biomass dynamic of Masson pine stands at pole stage with variant densities after thinning was analyesed. The results indicate that the tree biomass decreases in pace with stand density increase and accumalates with stand age. After thinning, the biomass of leaves and branches decrease at first and then increase with stand growth. The dynamic of stand biomass after thinning demonstrates that the stand with density of 3 000 trees·hm -2 remains to hold the highest biomass because it is the density suitable for masson pines. For the excessive high density stands, thinning should be carried out. Thinning time in stands with density of 3 000 trees·hm -2 and 3 750 trees·hm -2 is 20 years, and for stands with density of 4 515 trees·hm -2 ,it is 17 years.