Shi Jingwei, Deng Lei, Wu Jianzhao, Bai Edith, Chen Ji, Shangguan Zhouping, Kuzyakov Yakov
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, the Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling, Shaanxi, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, Yangling, Shaanxi, China.
Glob Chang Biol. 2024 Dec;30(12):e17616. doi: 10.1111/gcb.17616.
Microbial carbon (C) use efficiency (CUE) describes the proportion of organic C used by microorganisms for anabolic processes, which increases with soil organic C (SOC) content on a global scale. However, it is unclear whether a similar relationship exists during natural vegetation restoration in terrestrial ecosystems. Here, we investigated the patterns of CUE along a 160-year vegetation restoration chronosequence (from farmland to climax forest) estimated by stoichiometric modeling; additionally, we examined the relationship between CUE and SOC content and combined these results with a meta-analysis. The combination indicated that vegetation restoration decreased CUE from 0.35 to 0.28. Surprisingly, SOC content increased with decreasing CUE during vegetation restoration because forest soils have low pH values and high microbial phosphorus limitations compared to early ecosystems, implying that climax forests may not sequester as much soil C as expected. The shift in soil pH was the most important predictor of CUE compared to climate, plant, and microbial factors. CUE changes were directly induced by soil pH and not by the pH-induced microbial community. Alkaline soil acidification tended to decrease CUE. This first large-scale estimate of the relationship between CUE and SOC during natural restoration highlights the need to strengthen C sink management in mature forests to sustain their C sequestration potential.
微生物碳（C）利用效率（CUE）描述了微生物用于合成代谢过程的有机碳比例，在全球范围内，该比例随土壤有机碳（SOC）含量的增加而增加。然而，在陆地生态系统的自然植被恢复过程中，是否存在类似的关系尚不清楚。在此，我们通过化学计量模型研究了沿160年植被恢复时间序列（从农田到顶极森林）的CUE模式；此外，我们还研究了CUE与SOC含量之间的关系，并将这些结果与荟萃分析相结合。综合分析表明，植被恢复使CUE从0.35降至0.28。令人惊讶的是，在植被恢复过程中，CUE降低时SOC含量却增加了，因为与早期生态系统相比，森林土壤的pH值较低且微生物磷限制较高，这意味着顶极森林可能无法像预期的那样固存那么多的土壤碳。与气候、植物和微生物因素相比，土壤pH值的变化是CUE最重要的预测因子。CUE的变化是由土壤pH值直接引起的，而不是由pH值引起的微生物群落变化引起的。碱性土壤酸化往往会降低CUE。这项对自然恢复过程中CUE与SOC之间关系的首次大规模评估强调，需要加强成熟森林的碳汇管理，以维持其碳固存潜力。
