皆伐火烧对中亚热带米槠次生林生态系统碳贮量的影响

Carbon Pools in Secondary Forest of Castanopsis carlesis and Changes Associated with Clear-cutting and Burning in Mid-subtropical China

通过对中亚热带米槠次生林皆伐、火烧前后生态系统（乔木层地上部分和地下部分、林下植被层、枯枝落叶层及0～100 cm矿质土壤层）碳贮量变化进行研究,探讨皆伐火烧对中亚热带米槠次生林生态系统碳贮量的影响.结果表明,米槠次生林皆伐前生态系统碳贮量为278.6 t·hm-2,其中乔木层占64%,而林下植被层与枯枝落叶层碳贮量较低;皆伐后,树干（包含树皮）及粗枝被移出生态系统,其中包含97.5 t·hm-2的碳,相当于生态系统碳贮量的35%.火烧后2 d,采伐剩余物（包含枯枝落叶层物）碳贮量损失31.9 t·hm-2,损失率高达87%,而土壤表层（0～10 cm）碳贮量为（20.0 t·hm-2）,较火烧前下降了18%.由此可见,皆伐和火烧均造成生态系统碳贮量显著下降。

Ecosystem carbon pools（ above- and below-ground tree, understorey vegetation,forest floor,0 ～ 100 cm mineral soil layer） in a secondary forest of Castanopsis carlesis in subtropical China were examined before and after clear-cutting and burning. The aim of this paper was to discuss the influence of clear-cutting and burning on ecosystem carbon pools and the results showed that： The ecosystem carbon pool of the secondary forest of Castanopsis carlesis was 278. 6 t·hm- 2,in which the trees accounted for 64% and the understory vegetation and forest floor was smaller. After clear-cutting,97. 5 t·hm- 2C in stem wood with bark and coarse branches were removed from the ecosystem,which was amounted to 35% of the ecosystem carbon pool. Two days after burning,C removal from logging residues（ including forest floor material） was 31. 9 t·hm- 2with loss rate of87%. In addition,compared with the pre-burn level,the content of carbon in the topsoil（ 0 ～ 10cm） were reduced by 18% two days after burning. In conclusion,clear-cutting and slash burning had caused significant changes in ecosystem carbon pool.