凋落物分解是土壤有机碳的重要来源,对维持森林生态系统的稳定起着关键作用。不同城市森林种植模式凋落物木质纤维素降解过程中土壤有机碳(SOC)形成的微生物机理尚不清楚。关键基因,微生物,通过宏基因组学和代谢组学在不同城市森林种植模式的不同凋落物分解层和土壤层中测定了木质纤维素降解和SOC形成过程中的代谢产物,包括三种类型的阔叶林(BP森林),三种针叶林(CP林),和两种针叶阔叶混交林(MCBP林)。结果表明,纤维素,半纤维素,CP凋落物从未分解层到完全分解层的木质素浓度分别下降了70.07、86.83和73.04%;BP凋落物分别为74.30、93.80和77.55%;MCBP凋落物分别为62.51、48.58和90.61%;分别。0~10cm土层BP林和MCBP林土壤有机碳分别比CP林高出38.06和94.43%,10~20cm土层高出38.55和20.87%,分别。此外,BP森林中糖苷水解酶(GHs)和多糖裂解酶(PLs)的基因丰度高于MCBP森林和CP森林。氨基酸代谢,糖代谢,TCA代谢,cAMP信号代谢主要在CP林和BP林之间,而TCA循环,丙酮酸代谢,苯丙氨酸代谢,在凋落物分解过程中,酪氨酸代谢主要在BP森林和MCBP森林之间。此外,氨氮和半纤维素是驱动CP森林SOC形成的关键因素,而氨氮,半纤维素,木质纤维素降解基因是驱动BP森林SOC形成的关键因素。对于MCBP森林,纤维素,pH值,氨氮,木质素是SOC形成的关键因素。我们的发现表明,BP森林和MCBP森林在SOC形成中具有更强的木质纤维素降解性能。本研究为不同城市森林经营模式下养分的流动和转化提供了理论依据。
Litter decomposition is an important source of soil organic carbon, and it plays a key role in maintaining the stability of forest ecosystems. The microbial mechanism of soil organic carbon (SOC) formation in different urban forest planting patterns during litter lignocellulose degradation is still unclear. The key genes, microbes, and metabolites in the process of lignocellulose degradation and SOC formation were determined by metagenomics and metabolomics in different litter decomposition layers and soil layers in different urban forest planting patterns, including three types of broadleaf forests (BP forests), three types of coniferous forests (CP forests), and two types of mixed coniferous and broadleaf forests (MCBP forests). The results indicated that the cellulose, hemicellulose, and lignin concentrations from the undecomposed layer to the totally decomposed layer decreased by 70.07, 86.83, and 73.04% for CP litter; 74.30, 93.80, and 77.55% for BP litter; and 62.51, 48.58, and 90.61% for MCBP litter, respectively. The soil organic carbon of the BP forests and MCBP forests was higher than that of the CP forests by 38.06 and 94.43% for the 0-10 cm soil layer and by 38.55 and 20.87% for the 10-20 cm soil layer, respectively. Additionally, the gene abundances of glycoside hydrolases (GHs) and polysaccharide lyases (PLs) in the BP forests were higher than those in the MCBP forests and CP forests. Amino acid metabolism, sugar metabolism, TCA metabolism, and cAMP signaling metabolism were mainly between the CP forests and BP forests, while the TCA cycle, pyruvate metabolism, phenylalanine metabolism, and tyrosine metabolism were mainly between the BP forests and MCBP forests during litter decomposition. Additionally, ammonia nitrogen and hemicellulose were key factors driving SOC formation in the CP forests, while ammonia nitrogen, hemicellulose, and lignocellulose-degrading genes were key factors driving SOC formation in the BP forests. For the MCBP forests, cellulose, pH, ammonia nitrogen, and lignin were key factors driving SOC formation. Our findings revealed that the BP forests and MCBP forests had stronger lignocellulose degradation performance in the formation of SOC. This study provided a theoretical basis for the flow and transformation of nutrients in different urban forest management patterns.