阿尔泰山冷杉林下土壤有机碳矿化特征

目的]探讨阿尔泰山天然冷杉混交林不同海拔梯度下土壤有机碳矿化特征,为天然冷杉林土壤有机碳的分解转化过程研究提供理论依据。方法]以新疆布尔津县境内阿尔泰山1 300~1 500,1 500~1 700,1 700~1 900m这3个海拔梯度的冷杉(Abies nephrolepis)混交林下土壤为研究对象,在研究了土壤有机碳含量特征的基础上,进一步利用双指数模型对有机碳矿化特点进行了探讨。结果](1)3个海拔梯度的土壤有机碳含量均表现出随土层加深而降低的趋势,表层富集现象明显,且该趋势不随海拔梯度的变化而变化;(2)3个海拔梯度的各土层有机碳矿化趋势相似。即矿化初期CO2-C累积量增幅较大,而到了中、后期矿化曲线逐渐趋于平缓,CO2-C累积量增幅减小;(3)双指数方程可以很好地拟合出冷杉林土壤有机碳的矿化趋势;(4)土壤有机碳矿化过程进行到100d时各海拔梯度的各土层活性碳均未被完全分解;(5)矿化碳与土壤有机碳总量和活性碳含量均达到极显著相关水平。结论]土壤有机碳矿化过程表现出明显随海拔变化的特征。土壤活性碳含量是影响矿化作用的直接因素。

Mineralization Characteristics of Soil Organic Carbon Under Abies Nephrolepis Forest in Altai Mountains

Objective] The research was conducted to analyze the mineralization characteristics of soil organic carbon in Abies nephrolepis forest at different elevations in Altai mountains in order to provide the theoretic basis for the decompose and conversion processe study of soil organic carbon under A.nephrolepis forest. Method] The soil samples were collected in A.nephrolepis mixed forests at elevation of 1 300~1 500 m, 1 500~1 700 m and 1 700~1 900 m in Altai mountains in Burqin County in Xinjiang Uygur Autonomous Region, and soil organic carbon content was analyzed and compared. The mineralization characteristics of soil organic carbon were further explored using double exponential equation. Results] (1) Soil organic carbon and active carbon content decreased with increasing soil depth in all three elevation gradient, and the surface accumulation was obvious. (2) The trend of mineralization of soil organic carbon at three elevation gradient was similar. The cumulant of CO₂-C was bigger at early stage of mineralization. In the middle and late stage, the curve flatten out gradually, the increasing rate of cumulant of CO₂-C decreased. (3) The mineralization characteristics of soil organic carbon in A.nephrolepis forest in each layer can be well simulated using double exponential equation. (4) After 100 days of mineralization, the soil activated carbon at each elevation gradient was not still fully decomposed. (5) Mineralized carbon and soil total organic carbon and active carbon content were significantly correlated. Conclusion] The mineralization process of soil organic carbon obviously varied with elevation, soil active carbon concentration affected mineralization process directly.