The effect of mineral properties on soil organic carbon (SOC) destabilization processes is poorly known. Andisols developed under temperate old-growth rain forest store important amounts of SOC due to strong mineral adsorption capacity. We evaluated the effect of mineral soil properties on microbial activity and native SOC mineralization in an incubation experiment with and without the addition of labile organic carbon (C) and nutrients. Top- and subsoil horizons of two Andisols with contrasting age from temperate old-growth rain forest were sampled. We used the selective dissolution methods to determine the metals complexed with SOC and allophane content. Radiocarbon analysis activity was performed to determine the 14 C activity and 14 C ages of all soils as a proxy for SOC persistence. Additionally, we carried out a laboratory incubation under controlled conditions with and without 13 C labeled cellulose and nutrient solution (NH 4 NO 3 , KH 2 PO 4 ) addition. A lower microbial activity in the subsoils of both Andisols compared to topsoils in accordance with the lower 14 C activity at depth was recorded. After cellulose and nutrient additions, both subsoils horizons showed native SOC mineralization after 80 days of incubation. In contrast, these amendments did not induce native SOC mineralization in topsoils showing differences on C turnover rates between top- and subsoil horizons. In both soils, the native SOC mineralization after labile C and nutrient additions was negatively related to Na-pyrophosphate extractable C and may therefore be controlled by the formation of organo-mineral complexes with increasing soil C age. We conclude that the physicochemical soil characteristics evolving during pedogenesis control the SOC stabilization and also destabilization processes in Andisols developed under temperate old-growth rain forests.

中文翻译：

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温带原始雨林下两种山地土壤表层和底土层的碳矿化控制

矿物特性对土壤有机碳 (SOC) 不稳定过程的影响知之甚少。由于强大的矿物吸附能力，在温带原始雨林下发育的 Andisol 储存了大量的 SOC。我们在添加和不添加不稳定有机碳 (C) 和养分的孵化实验中评估了矿质土壤特性对微生物活性和天然 SOC 矿化的影响。对来自温带古老雨林的两种具有不同年龄的安迪索的表层和底土层进行了采样。我们使用选择性溶解方法来确定与 SOC 和水铝烷含量络合的金属。进行放射性碳分析活动以确定所有土壤的 14 C 活动和 14 C 年龄，作为 SOC 持久性的代表。此外，我们在有和没有 13 C 标记的纤维素和营养液（NH 4 NO 3 、KH 2 PO 4 ）添加的受控条件下进行了实验室培养。与表层土相比，两种 Andisol 的底土中的微生物活性较低，这与深度处较低的 14 C 活性一致。添加纤维素和养分后，两个底土层在培养 80 天后都显示出天然 SOC 矿化。相比之下，这些修正并未在表层土壤中诱导原生 SOC 矿化，显示表层和底土层之间的 C 周转率存在差异。在这两种土壤中，添加不稳定 C 和养分后的天然 SOC 矿化与焦磷酸钠可提取 C 呈负相关，因此可能受随着土壤 C 年龄增加而形成的有机矿物复合物的控制。