摘要：土壤有机碳库是陆地生态系统碳汇的重要组成部分，探明土壤有机碳的转化与稳定机制是深入理解陆地生态系统碳汇功能及应对气候变化的关键。植物作为有机碳的初始来源，微生物同化产物也是土壤有机碳的重要贡献者，二者对有机碳的固存机制有着重要影响。但由于植物残体分解过程的复杂性、多变性以及参与分解过程的微生物种群的高异质性，植物残体和微生物残体向土壤有机碳的贡献和稳定机理尚不十分明确。本研究选取我国西南典型岩溶山区的草地、灌草、灌丛初期、灌丛后期及乔木林五个恢复阶段为研究对象，利用时空替代法，组成自然恢复序列，利用生物标志物技术对土壤中植物来源和微生物来源的有机碳进行定量分析。结果发现：微生物残体碳的含量会随着植被正向恢复而明显增加，但其对SOC的贡献率较低；真菌残体碳的含量及其对SOC的贡献明显高于细菌残体碳；氨基葡萄糖与胞壁酸的比值走势显示，植被恢复对SOC的积累产生了正面的影响。木质素酚单体的含量变化显示，植被恢复过程中，木本和被子植物丰度有所增加，而草本植物减少；木质素积累是植被恢复过程中SOC增加的一个重要机制；矿物成分如可交换态钙、镁，游离铁铝氧化物都可能影响木质素的积累。
关键词：土壤有机碳；土壤微生物；植物残体；微生物残体；岩溶区
Abstract: The soil organic carbon pool is a significant component of the carbon pool in terrestrial ecosystems, and its transformation and stabilization mechanism is crucial for better understanding the function of the carbon pool in terrestrial ecosystems and for coping with climate change. Plants as the initial source of organic carbon and microbial assimilation products are also important contributors to soil organic carbon, and both have an important influence on the sequestration mechanism of organic carbon. However, the contribution of plant residues and microbial residues to soil organic carbon and the stabilization mechanism are not yet clear. In this study, five restoration stages of grassland, mixed shrub-grassland, early scrubland, late scrubland, and mature forest in typical karst mountainous areas in Southwest China were selected, and the space-time substitution method was used to make up a natural restoration sequence. We quantitatively assess the contributions of plant-derived and microbial-derived organic carbon to soil dynamics. The results revealed that: the content of microbial residue carbon increases significantly with positive vegetation restoration, but its contribution to SOC is relatively low; the content of fungal residue carbon and its contribution to SOC is significantly higher than that of bacterial residue carbon; and the trend of the ratio of GluN/MurN shows that vegetation restoration positively influences the accumulation of SOC. Changes in the content of lignin phenols showed an increase in the abundance of woody and angiosperm plants and a decrease in herbaceous plants during vegetation restoration; Changes in the content of lignin phenolic monomers showed an increase in the abundance of woody and angiosperm plants and a decrease in herbaceous plants during vegetation restoration; lignin accumulation is an important mechanism for the increase in SOC during vegetation restoration; and mineral constituents, such as Fe_o, Al_o, Ca_exe, and Mg_exe may influence the accumulation of lignin.
 

土壤有机碳；土壤微生物；植物残体；微生物残体；岩溶区