Soil organic carbon (SOC) mineralization is a process driven by microorganisms and is considered to be one of the main forms of carbon loss in land restoration. However, the interaction of SOC structures and bacteria that drive SOC mineralization remain unclear. Therefore, four forest succession stages were investigated on the Loess Plateau of Northern China: (1) primary stage Betula platyphylla (BP); (2) transitional stage which were two mixed communities of Populus davidiana and Quercus wutaishanica with different proportions (PQ1); (3) (PQ2) and (4) the late stage was climax communities of Quercus wutaishanica (QW). The Illumina sequencing of the 16S rRNA gene and Fourier transformation infrared (FTIR-ATR) spectroscopy were used to clarify the regulation mechanism of microbial activity on SOC mineralization during forest succession through the perspective of SOC structures. Our results indicated higher aromatics-C in QW contributed to decreased SOC mineralization ratio (SMR). Redundancy analysis confirmed SOC structures–bacteria interaction and revealed the groups Acidobacteria correlated with recalcitrant SOC structures while Proteobacteria and Bacteroides correlated with labile SOC structures, respectively. Moreover, the partial least squares path model revealed that the SOC and C:N ratio act on soil bacteria community characteristics, and the higher abundance of Acidobacteria and the increase of aromatics-C decreased SMR. Collectively, these findings highlight the importance of bacteria–SOC structures interaction in decreased SMR and contribute to an improved understanding of how forest succession regulates carbon mineralization.

中文翻译：

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黄土高原森林演替过程中土壤生化特征和土壤有机碳（SOC）结构对SOC矿化速率的贡献

土壤有机碳（SOC）矿化是由微生物驱动的过程，被认为是土地恢复中碳损失的主要形式之一。然而，驱动 SOC 矿化的 SOC 结构和细菌的相互作用仍不清楚。因此，研究了华北黄土高原四个森林演替阶段：（1）初级阶段白桦（BP）；(2)不同比例的山杨和五台山栎两个混合群落的过渡期(PQ1)；(3)(PQ2)和(4)后期是五台山栎的高潮群落(QW)。16S rRNA基因的Illumina测序和傅里叶变换红外（FTIR-ATR）光谱从SOC结构的角度阐明了森林演替过程中微生物活性对SOC矿化的调控机制。我们的结果表明，QW 中较高的芳烃-C 有助于降低 SOC 矿化率 (SMR)。冗余分析证实了 SOC 结构-细菌相互作用，并揭示了酸杆菌组与顽固的 SOC 结构相关，而变形菌和拟杆菌分别与不稳定的 SOC 结构相关。此外，偏最小二乘路径模型表明，SOC和C:N比对土壤细菌群落特征有影响，而较高的酸杆菌丰度和芳烃-C的增加会降低SMR。集体，