Understanding the effect of soil erosion on soil carbon (C) fixation is of great significance for evaluating the complicated connection between land degradation and C cycle. To investigate erosion‐induced changes in autotrophic bacterial community and microbial carbon dioxide (CO₂) fixation, three typical eroding sites and three depositional sites were selected in the hilly red soil region of southern China with severe erosion. Positive responses of autotrophic microbial abundance to soil deposition were observed, whereas no obvious changes in microbial diversity were observed between eroding and depositional sites. The relative abundances of obligate autotrophic bacteria, such as Rhodopseudomonas and Pseudonocardia, were enhanced in the eroding sites. Deposition of organic matter‐rich soil was not conducive to the growth of obligate autotrophic bacteria. The average rate and amount of microbial CO₂ fixation at the depositional sites (30.86 mg C km⁻² year⁻¹ and 0.05 g kg⁻¹) were higher than those at the eroding sites (18.04 mg C km⁻² year⁻¹ and 0.025 g kg⁻¹), which indicated that soil deposition significantly enhanced autotrophic microbial CO₂ fixation. In addition, multiple stepwise linear regression showed that compared with microbial properties (abundance and diversity), dissolved organic carbon is a more important explanation factor for the change of microbial CO₂ fixation rate (68.8%, P = 0.001).

中文翻译：

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在被侵蚀的流域中，不稳定的有机物比自养细菌群落起着更重要的作用，用于调节微生物对二氧化碳的固定

了解土壤侵蚀对土壤碳（C）固定的影响对于评估土地退化与碳循环之间的复杂联系具有重要意义。为了研究侵蚀引起的自养细菌群落和微生物二氧化碳（CO ₂）固定的变化，在华南丘陵红壤严重侵蚀的地区选择了三个典型的侵蚀点和三个沉积点。观察到自养微生物丰富度对土壤沉积的积极反应，而在侵蚀和沉积位点之间未观察到微生物多样性的明显变化。专性自养细菌的相对丰度，例如杜鹃假单胞菌和假性心动过速，在腐蚀部位得到了增强。富含有机物的土壤的沉积不利于专性自养细菌的生长。沉积位点的平均微生物CO ₂固定速率和数量（30.86 mg C km - ² 年^-1和0.05 g kg ^-1）高于侵蚀位点（18.04 mg C km - ² 年^-1和1.0 g）。0.025 g kg ^-1），这表明土壤沉积显着增强了自养微生物CO ₂固定。此外，多元逐步线性回归表明，与微生物特性（丰度和多样性）相比，溶解的有机碳是微生物CO ₂固着率变化的更重要的解释因素（68.8％，P  = 0.001）。