Abstract. Climate and parent material both affect soil C persistence, yet the relative importance of climatic versus mineralogical controls on soil C dynamics remains unclear. To test this, we collected soil samples in 2001, 2009, and 2019 along a combined gradient of parent material (andesite, basalt, granite) and climate (mean annual temperature (MAT): 6.5 °C “cold”, 8.6 °C “cool”, 12.0 °C “warm”). We measured the radiocarbon of heterotrophically respired CO₂ (∆¹⁴C_respired) and bulk soil C (∆¹⁴C_bulk) as proxies for transient and persistent soil C, and characterized mineral assemblages using selective dissolution. Using linear regression, we observed that MAT was not a significant predictor of either ∆¹⁴C_bulk or ∆¹⁴C_respired, yet climate was highly significant as a categorical variable. Climate explained more variance in ∆¹⁴C_bulk and ∆¹⁴C_respired over 0–0.1 m, but parent material explained more from 0.1–0.3 m. Cool site soil C was more persistent (lower ∆¹⁴C_bulk) than cold or warm climate sites, and also more persistent on andesitic soils, followed by basaltic and then granitic soils. Poorly crystalline metal oxides (PCMs) (but not crystalline metal oxides) were significantly (p < 0.1) correlated with ∆¹⁴C_bulk, ∆¹⁴C_respired, and ∆¹⁴C_respired - ∆¹⁴C_bulk, indicating their importance for soil C cycling on both short and long timescales. The change in ∆¹⁴C_respired observed over the study period was linearly related to MAT for the granite soils with the lowest PCM content, but not in the andesitic and basaltic soils with higher PCM content. This link between PCM abundance and the decoupling of MAT and soil C cycling rates suggests PCMs may attenuate the temperature sensitivity of decomposition.

中文翻译：

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土壤矿物质在每年到百年时间尺度上调节土壤碳循环的气候控制

摘要。气候和母质都会影响土壤碳的持久性，但气候与矿物学控制对土壤碳动态的相对重要性仍不清楚。为了测试这一点，我们在 2001 年、2009 年和 2019 年沿母质（安山岩、玄武岩、花岗岩）和气候（年平均温度 (MAT)：6.5°C“冷”、8.6°C“冷”，12.0 °C“暖”）。我们测量了异养呼吸的 CO ₂ (∆ ¹⁴ C _respired ) 和散装土壤 C (∆ ¹⁴ C _bulk) 作为瞬时和持久土壤 C 的代表，并使用选择性溶解来表征矿物组合。使用线性回归，我们观察到 MAT 不是 ∆ ¹⁴ C _bulk或 ∆ ¹⁴ C _respired的显着预测因子，但气候作为分类变量非常重要。气候解释了 Δ ¹⁴ C_体积和 Δ ¹⁴ C在 0-0.1 m 范围内_呼吸的更多变化，但母质在 0.1-0.3 m 范围内解释更多。凉爽的场地土壤 C 更持久（较低的 Δ ¹⁴ C_体积) 比寒冷或温暖的气候地点更持久，并且在安山质土壤上更持久，其次是玄武质土壤，然后是花岗岩土壤。结晶性差的金属氧化物 (PCM)（但不是结晶金属氧化物）与 Δ ¹⁴ C_体积、Δ ¹⁴ C_呼吸和 Δ ¹⁴ C_呼吸- Δ ¹⁴ C_体积显着相关（p < 0.1） ，表明它们对土壤 C 的重要性在短期和长期的时间尺度上循环。Δ ¹⁴ C_{呼吸的变化}对于 PCM 含量最低的花岗岩土壤，在研究期间观察到的 MAT 与 MAT 呈线性相关，但在 PCM 含量较高的安山岩和玄武岩土壤中则没有。PCM 丰度与 MAT 和土壤 C 循环速率之间的这种联系表明 PCM 可能会减弱分解的温度敏感性。