大量稳定的土壤有机质(SOM)来源于微生物坏死,这可以通过定量氨基糖生物标志物来评估。马尾松羔羊.人工林在我国分布广泛,在森林固碳中起着至关重要的作用。然而,土壤微生物残留的模式仍然知之甚少。在这项研究中,氨基糖用于表征不同年龄马尾松人工林中三个土壤深度(0-10、10-20和20-30cm)的土壤微生物残留模式(年轻,中年,接近成熟,成熟,和过度成熟;表示为YG,MD,NM,MT,OM,分别)。在表土(0-10厘米),OM林的总氮(TN)含量最高,而MT森林的土壤有机碳(SOC)含量最高。与SOC和TN的变化一致,随着土壤深度的增加,微生物总残留含量下降。然而,随着深度的增加,总微生物残留物C对SOC的贡献显著增加,表明底土中的微生物残留物比表土中的微生物残留物更多的SOC。真菌残留C对SOC的贡献高于细菌残留C。表土中总氨基糖含量随着年龄的增加而增加,MT和OM的含量明显高于其他森林。在所有土壤深度,SOC和TN含量主要决定微生物坏死,而土壤微生物生物量含量主要决定表层土壤中的微生物坏死量;土壤pH值主要决定10-20cm土壤层中的微生物坏死量;土壤pH值和Ca2含量是20cm以下土壤层的主要因素。该研究为控制微生物衍生的有机碳提供了有价值的见解,可用于地球系统研究,以预测森林中的SOC动态。
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 Ca2+ 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.