Ecology and Nature Conservation Institute, Chinese Academy of Forestry; Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Beijing, 100091, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
Ecology and Nature Conservation Institute, Chinese Academy of Forestry; Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Beijing, 100091, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
Environ Res. 2023 Aug 15;231(Pt 2):116081. doi: 10.1016/j.envres.2023.116081. Epub 2023 May 8.
A large amount of stable soil organic matter (SOM) is derived from microbial necromass, which can be assessed by quantifying amino sugar biomarkers. Pinus massoniana Lamb. Plantations are widely distributed in China and play a vital role in forest carbon sequestration. However, the patterns of soil microbial residue remain poorly understood. In this study, amino sugars were used to characterize patterns of soil microbial residues at three soil depths (0-10, 10-20, and 20-30 cm) in P. massoniana plantations of different ages (young, middle-aged, near-mature, mature, and over-mature; denoted as YG, MD, NM, MT, and OM, respectively). In the topsoil (0-10 cm), the total nitrogen (TN) content of the OM forest was the highest, whereas the soil organic carbon (SOC) content of the MT forest was the highest. Consistent with changes in SOC and TN, total microbial residue content decreased with increasing soil depth. However, the total microbial residues C to SOC contribution increased considerably with increasing depth, suggesting that more SOC was derived from microbial residues in the subsoil than that from the topsoil. The fungal residue C to SOC contribution was higher than that of bacterial residue C. Total amino sugar content in the topsoil increased with increasing age, and MT and OM had a significantly higher content than that of other forests. At all soil depths, SOC and TN content predominantly determined microbial necromass, whereas soil microbial biomass content predominantly determined microbial necromass in the topsoil; soil pH predominantly determined microbial necromass in the 10-20 cm soil layer; and soil pH and Ca content were the primary factors in the soil layer below 20 cm. The study provides valuable insights into controls of microbial-derived organic C could be applied in Earth system studies for predicting SOC dynamics in forests.
大量稳定的土壤有机碳（SOM）来源于微生物残体，可以通过定量测定氨基糖生物标志物来评估。马尾松人工林在中国广泛分布，对森林碳固存起着至关重要的作用。然而，土壤微生物残体的模式仍不清楚。本研究采用氨基糖来描述不同林龄（幼龄、中龄、近熟、成熟和过熟，分别记为 YG、MD、NM、MT 和 OM）马尾松人工林三个土层（0-10、10-20 和 20-30 cm）的土壤微生物残体模式。在表层土壤（0-10 cm）中，OM 林的全氮（TN）含量最高，而 MT 林的土壤有机碳（SOC）含量最高。与 SOC 和 TN 的变化一致，总微生物残体含量随土层深度的增加而降低。然而，总微生物残体 C 对 SOC 的贡献随着深度的增加而显著增加，这表明在亚表层土壤中，更多的 SOC 来源于微生物残体，而不是来源于表层土壤。真菌残体 C 对 SOC 的贡献高于细菌残体 C。表层土壤中总氨基糖含量随林龄的增加而增加，MT 和 OM 明显高于其他林分。在所有土层中，SOC 和 TN 含量主要决定了微生物残体，而土壤微生物生物量含量主要决定了表层土壤中的微生物残体；土壤 pH 值主要决定了 10-20 cm 土层中的微生物残体；土壤 pH 值和 Ca 含量是 20 cm 以下土层中的主要因素。该研究为预测森林土壤 SOC 动态提供了微生物来源有机碳控制的有价值的见解，可以应用于地球系统研究。
