培养条件下枯落物分解过程中微生物残体对土壤有机碳形成的贡献

doi:10.13287/j.1001-9332.202307.004

摘要/Abstract

摘要： 采用黄土丘陵区多年生C3草本植物长芒草为对象,模拟“枯落物-土壤”转换界面,进行了为期512 d的室内分解试验,对枯落物分解过程中界面土层微生物残体和土壤碳组分动态进行了研究。结果表明: 土壤微生物残体的形成在分解早期和中期由真菌主导,而在晚期由细菌主导。真菌残体碳对矿物结合态有机碳的贡献率(38.7%～75.8%)明显高于细菌(9.2%～22.5%),是细菌残体贡献率的3～4倍。土壤有机碳含量在枯落物分解过程中呈下降趋势。植物碳源的输入调动了微生物对土壤碳组分的利用。颗粒态有机碳分解早期和晚期持续下降,成为土壤有机碳含量减少的直接原因;而微生物残体碳和矿质结合态有机碳的波动变化对土壤有机碳含量的降低只起到间接作用。一次性外源添加枯落物引起的土壤微生物残体碳的增加并没有直接贡献土壤有机碳的积累。

关键词: 转化界面土层, 土壤微生物残体碳, 土壤矿质结合态有机碳, 土壤有机碳

Abstract: We conducted a 512-day incubation experiment to study the dynamics of microbial necromass and soil carbon fraction in the ‘litter-soil’ transformation interface soil layer (TIS) during litter decomposition, using a perennial C3 herb, Stipa bungeana, in the loess hills. The results showed that soil microbial necromass was dominated by fungi in the early and middle stages, and by bacteria in the late stage. The contribution of fungal necromass C to mineral-associated organic C (MAOC) was significantly higher (38.7%-75.8%) than that of bacteria (9.2%-22.5%) and 2-3 times more than the contribution rate of bacterial necromass. Soil organic C (SOC) content was decreasing during litter decomposition. The input of plant C resources stimulated microbial utilization of soil C fractions. The continuous decrease in particulate organic C during the early and late stages of decomposition was directly responsible for the decrease in SOC content. In contrast, the fluctuating changes in microbial necromass C and MAOC played an indirect role in the reduction of SOC. The increase in soil microbial necromass C caused by a single exogenous addition of litter did not directly contribute to SOC accumulation.

Key words: transformation interface soil layer, soil microbial necromass carbon, soil mineral-associated carbon, soil organic carbon

薛志婧, 屈婷婷, 刘春晖, 刘小槺, 王蕊, 王宁, 周正朝, 董治宝. 培养条件下枯落物分解过程中微生物残体对土壤有机碳形成的贡献[J]. 应用生态学报, 2023, 34(7): 1845-1852.

XUE Zhijing, QU Tingting, LIU Chunhui, LIU Xiaokang, WANG Rui, WANG Ning, ZHOU Zhengchao, DONG Zhibao. Contribution of microbial necromass to soil organic carbon formation during litter decomposition under incubation conditions[J]. Chinese Journal of Applied Ecology, 2023, 34(7): 1845-1852.

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