Hu Jian-Wen, Liu Chang-Fu, Gou Meng-Meng, Chen Hui-Ling, Lei Lei, Xiao Wen-Fa, Zhu Su-Feng, Hu Ru-Yuan
Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China.
Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China.
Ying Yong Sheng Tai Xue Bao. 2024 Jan;35(1):153-160. doi: 10.13287/j.1001-9332.202401.041.
Clarifying the accumulation pattern of soil microbial residue carbon and its contribution to soil organic carbon (SOC) across stand age is helpful to understand the mechanism underlying soil carbon cycling. In this study, we analyzed the differences of amino sugar content, physicochemical properties and microbial composition in surface soil (0-10 cm) in young (6 a), middle-aged (13 a), near-mature (29 a), mature (38 a) and over-mature (57 a) plantations of subtropical China, quantified the microbial residue carbon content and its contribution to SOC, and discussed the mechanism. The results showed that SOC, total nitrogen, amorphous iron oxide and leucine aminopeptidase contents in the middle-aged plantation were significantly lower than those in the mature plantation. Soil pH and fungal/bacteria in young plantation were significantly higher than those in other age groups. Across the stand age gradient, the ranges of microbial, fungal and bacterial residue carbon were 7.52-14.63, 4.03-8.00 and 3.48-6.63 g·kg, respectively. The contents of all the residue carbon were significantly higher in the mature plantation than that of the middle-aged plantation, which were positively affected by soil total nitrogen content. The contribution of microbial, fungal, and bacterial residue carbon to SOC was 59.7%-72.3%, 33.4%-45.6%, and 24.3%-30.8%, respectively. The contribution of fungal residue carbon to SOC in young plantation was significantly higher than that in other age groups, and the contribution of bacterial residue carbon to SOC in middle-aged plantation was significantly higher than that in young and near-mature plantations, both of which were affected by soil inorganic nitrogen. Fungal residue carbon content was 1.2-1.7 times as that of bacterial residue carbon content, and dominated for the accumulation of microbial residue carbon. Results of the partial least squares model showed that stand age, soil environmental factors (such as leucine aminopeptidase, amorphous iron oxide, pH, and total nitrogen), bacterial residue carbon, fungal residue carbon and the contribution of bacterial residue carbon to SOC had total effects on the contribution of fungal residue carbon to SOC (-0.37, -1.16, 0.90, 1.09, and 0.83, respectively). In conclusion, stand age promoted the accumulation of microbial residue carbon but did not increase its contribution to SOC.
阐明土壤微生物残体碳的积累模式及其在不同林龄阶段对土壤有机碳（SOC）的贡献，有助于理解土壤碳循环的潜在机制。在本研究中，我们分析了中国亚热带地区幼龄（6年）、中年（13年）、近成熟（29年）、成熟（38年）和过成熟（57年）人工林表层土壤（0-10厘米）中氨基糖含量、理化性质和微生物组成的差异，量化了微生物残体碳含量及其对SOC的贡献，并探讨了其机制。结果表明，中年人工林的SOC、全氮、无定形氧化铁和亮氨酸氨肽酶含量显著低于成熟人工林。幼龄人工林的土壤pH值和真菌/细菌比值显著高于其他年龄组。在整个林龄梯度上，微生物、真菌和细菌残体碳的范围分别为7.52-14.63、4.03-8.00和3.48-6.63克·千克。所有残体碳含量在成熟人工林中均显著高于中年人工林，且受到土壤全氮含量的正向影响。微生物、真菌和细菌残体碳对SOC的贡献分别为59.7%-72.3%、33.4%-45.6%和24.3%-30.8%。幼龄人工林中真菌残体碳对SOC的贡献显著高于其他年龄组，中年人工林中细菌残体碳对SOC的贡献显著高于幼龄和近成熟人工林，两者均受土壤无机氮的影响。真菌残体碳含量是细菌残体碳含量的1.2-1.7倍，在微生物残体碳的积累中占主导地位。偏最小二乘模型结果表明，林龄、土壤环境因子（如亮氨酸氨肽酶、无定形氧化铁、pH值和全氮）、细菌残体碳、真菌残体碳以及细菌残体碳对SOC的贡献对真菌残体碳对SOC的贡献均有总体影响（分别为-0.37、-1.16、0.90、1.09和0.83）。总之，林龄促进了微生物残体碳的积累，但并未增加其对SOC的贡献。
