Shen Ji-Kai, Huang Yi-Mei, Huang Qian, Xu Feng-Jing
College of Natural Resource and Environment, Northwest A&F University/Key Laboratory of Plant Nutrition and Agri-enviroment in Northwest China, Ministry of Agriculture and Rural Affairs/Key Laboratory of Low-carbon Green Agriculture in Northwestern China, Ministry of Agriculture and Rural Affairs, Yangling 712100, Shaanxi, China.
Ying Yong Sheng Tai Xue Bao. 2024 Jan;35(1):124-132. doi: 10.13287/j.1001-9332.202401.014.
Microbial necromass carbon (MNC) is an important contributor to soil organic carbon (SOC). Soil carbon storage has increased significantly since the return of farmland to forestland (grassland) on the Loess Plateau. However, the contribution of MNC to SOC accumulation in different vegetation types and the influence factors remain unclear. Herein, we used the biomarker (amino sugar) technique to determine the MNC content and analyzed the influencing factors in 0-5 cm and 5-20 cm soil layers of natural grassland, shrubland (), and forestland () in the Loess Plateau. The results showed that: 1) the soil pH decreased significantly from grassland to shrubland and then to forestland within the same soil layer. However, the SOC, total nitrogen (TN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) contents showed a reverse trend, with forestland displaying the highest values followed by shrubland and then grassland. The 0-5 cm had significantly higher values than the 5-20 cm depth. 2) The MNC contents varied 0.69-16.41 g·kg in the two soil horizons of the three vegetation types. There were significant increases in the contents of bacterial necromass carbon (BNC), fungal necromass carbon (FNC), and MNC in the 0-5 cm soil from grassland, shrubland to forestland. The contents of MBC were 1.9 times higher in forestland than in shrubland, and 3.2 times higher in shrubland than in grassland. In the 5-20 cm soil layer, the contents of FNC and MBC were significantly higher in the forestland than in the shrubland and grassland. The FNC content was significantly higher than that of the BNC, ranging from 1.16 to 9.83 times greater than the BNC. 3) The contribution of MNC to SOC was 0.6 and 0.7 times higher in shrubland and forestland than in grassland, respectively, with FNC accounting for 15.2%-42.7%, and BNC accounting for 1.4%-7.4%. 4) pH, TN, MBC, and MBN were important factors that influenced MNC accumulation. In summary, the variation in vegetation type altered soil nutrients, microbial activity, and soil pH, resulting in forestland and shrubland being more beneficial to the formation and accumulation of MNC, which was dominated by fungi, compared to grassland.
微生物残体碳（MNC）是土壤有机碳（SOC）的重要组成部分。自黄土高原退耕还林（草）以来，土壤碳储量显著增加。然而，MNC对不同植被类型土壤有机碳积累的贡献及其影响因素仍不清楚。在此，我们采用生物标志物（氨基糖）技术测定了黄土高原天然草地、灌丛地（）和林地（）0-5厘米和5-20厘米土层中的MNC含量，并分析了影响因素。结果表明：1）在同一土层内，土壤pH值从草地到灌丛地再到林地显著降低。然而，土壤有机碳、全氮（TN）、微生物生物量碳（MBC）和微生物生物量氮（MBN）含量呈现相反趋势，林地最高，其次是灌丛地，然后是草地。0-5厘米土层的值显著高于5-20厘米深度。2）三种植被类型的两个土壤层中，MNC含量在0.69-16.41克·千克之间变化。从草地、灌丛地到林地，0-5厘米土壤中细菌残体碳（BNC）、真菌残体碳（FNC）和MNC含量显著增加。林地MBC含量比灌丛地高1.9倍，灌丛地比草地高3.2倍。在5-20厘米土层中，林地FNC和MBC含量显著高于灌丛地和草地。FNC含量显著高于BNC，是BNC的1.16-9.83倍。3）MNC对土壤有机碳的贡献在灌丛地和林地分别比草地高0.6倍和0.7倍，其中FNC占15.2%-42.7%，BNC占1.4%-7.4%。4）pH值、TN、MBC和MBN是影响MNC积累的重要因素。综上所述，植被类型的变化改变了土壤养分、微生物活性和土壤pH值，导致林地和灌丛地比草地更有利于以真菌为主的MNC的形成和积累。
