中科院华南植物园博士王法明与美国纽约州立大学教授朱伟兴合作，发现森林恢复有利于提高土壤深层微团聚体组分和有机—矿质颗粒组分的含量，从而增加土壤碳的稳定性。近日，相关研究发表在《植物与土壤》上。

在森林生态恢复过程中，土壤碳的变化是现代生态学研究所关注的重点。森林的恢复可以促进土壤有机碳的固持，缓解气候变化和大气CO2上升所造成的影响。已有的实验研究表明，在小于30年的森林恢复过程中，阔叶树种相对于针叶树种能够固持更多的碳。但这些研究忽视了大于30年以上的森林生态恢复过程中土壤碳存储的变化。相对于阔叶树种，针叶树种的凋落物更难分解，理论上其土壤碳的固持量应高于阔叶树种。

研究人员对美国东北部有70年生态恢复历史的不同人工林进行土壤碳固存量和碳稳定性研究。长期观察与研究发现，经过70年的森林恢复，相对于阔叶树种，针叶树种更有利于土壤和地被层有机碳的积累。而且森林恢复有利于提高土壤深层微团聚体组分和有机—矿质颗粒组分的含量，从而增加土壤碳的稳定性。（来源：中国科学报 朱汉斌 周飞）

Changes of soil C stocks and stability after 70-year afforestation in the Northeast USA

Abstract  Background and aims Forest restoration has been proposed as an effective strategy for the sequestration of atmosphere CO2. Understanding the mechanisms of soil organic carbon (SOC) dynamics in afforestation is important to quantifying and enhancing carbon (C) sequestration. Methods After 70 years afforestation with two conifer and three broadleaf tree species in monocultures in Northeast USA, we measured soil C pools as well as C fractions in these plantations and nearby pasture control. Results Soil C stored in forest floor was increased by afforestation, especially in conifer stands. Total C stock in mineral soils was not statistically different among species, but C fractions had been altered. Compared to pasture land, afforestation decreased coarse particle organic C (cPOC) fraction, while increased recalcitrant mineral associated SOC (mSOC) fraction. Afforestation decreased the macro-aggregate C fraction in the 0–5 cm soil, but increased the micro-aggregate C fraction in the 5–15 cm soil. Conclusions 1) Afforestation using conifers could improve the whole soil-profile carbon stock compared to broadleaves when the forest floor is included; 2) Even though the overall mineral soil C stock was not changed, afforestation could improve soil C stabilization through increasing mSOC fraction and forming more micro-aggregate C fraction in deeper soils.

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