Precise assessment of soil organic carbon (OC) storage requires understanding of soil type and depth specific differences in organic matter (OM) stabilization. Therefore, we aimed to analyze OC dynamics down the soil profile and to clarify the effect of depth on the importance of aggregate formation and mineral adsorption for OC storage in mature beech forest soils developed from different parent materials. Aggregate size and density fractions were separated from samples of top and subsoil horizons, which were quantified and analyzed by infrared spectroscopy. We also determined the microbial biomass C (C mic ) and the amount of C decomposed within incubation experiments (CO 2 -C) for the bulk soil samples. OC stabilized via aggregate formation and mineral association significantly increased with soil depth. However, this stabilized pool seemed to fuel the labile OM stronger in the subsoil than in the topsoil because the CO 2 -C/SOC and CO 2 -C/C mic ratios increased with depth. Measured differences in the magnitude of the detected stabilization and destabilization patterns were attributed to parent material and soil horizon, indicating pronounced spatial and vertical heterogeneity in the contribution of soils under temperate broadleaf forest to terrestrial C sequestration. Considering such site and depth specific differences will improve assessment and modelling of soil OC storage for areas covered with the same forest type but with high pedogenetic diversity.

中文翻译：

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聚合体形成和有机矿物结合影响温带阔叶林跨土壤层和母质的土壤有机质特征

土壤有机碳 (OC) 储存的精确评估需要了解土壤类型和深度在有机质 (OM) 稳定性方面的特定差异。因此，我们旨在分析土壤剖面的 OC 动态，并阐明深度对由不同母材发育的成熟山毛榉森林土壤中聚集体形成和矿物质吸附对 OC 储存重要性的影响。从顶部和底土层的样品中分离出骨料尺寸和密度部分，通过红外光谱对其进行量化和分析。我们还确定了大块土壤样品的微生物生物量 C (C mic ) 和孵化实验中分解的 C 量 (CO 2 -C)。通过聚集体形成和矿物结合稳定的 OC 随着土壤深度显着增加。然而，由于 CO 2 -C/SOC 和 CO 2 -C/C mic 比率随着深度的增加而增加，这个稳定的池似乎在底土中比在表土中更能促进不稳定的 OM。检测到的稳定和不稳定模式大小的测量差异归因于母体材料和土壤层，表明温带阔叶林下土壤对陆地碳封存的贡献存在明显的空间和垂直异质性。考虑到此类地点和深度的特定差异，将改进对覆盖相同森林类型但具有高成土多样性的区域的土壤 OC 储存的评估和建模。检测到的稳定和不稳定模式大小的测量差异归因于母体材料和土壤层，表明温带阔叶林下土壤对陆地碳封存的贡献存在明显的空间和垂直异质性。考虑到此类地点和深度的特定差异，将改进对覆盖相同森林类型但具有高成土多样性的区域的土壤 OC 储存的评估和建模。检测到的稳定和不稳定模式大小的测量差异归因于母体材料和土壤层，表明温带阔叶林下土壤对陆地碳封存的贡献存在显着的空间和垂直异质性。考虑到此类地点和深度的特定差异，将改进对覆盖相同森林类型但具有高成土多样性的区域的土壤 OC 储存的评估和建模。