祁连山中部高山草甸土壤有机碳矿化及其影响因素研究

The mineralization of alpine meadow soil organic carbon and factors influencint it in the Qilian Mountain

分析了室内培养土壤温湿度变化对祁连山海拔3500，3600，3700和3800m处高寒草甸土壤有机碳矿化的影响。结果显示土壤有机碳累积矿化量及其比例为35℃下最高，土壤含水量为30％和40％下比10％和20％下高，0～15cm土层比15～35cm土层中高。土壤有机碳矿化速率及其占有机碳含量比例随培养时间延长而递减。土壤有机碳矿化速率及其比例为35℃下最高，土壤含水量为30％和40％下比10％和20％下高，0～15cm土层比15～35cm土层中高。一阶动态方程拟合土壤有机碳矿化动态效果较好。5℃下分解率系数和活性有机碳库较低。5℃升高到15℃，Q10为1～6，15℃升高到25℃．Q10为1～2。结果表明祁连山高寒草甸表层土壤有机碳分解受温湿度变化的影响较大。

The alpine meadow soil organic carbon （SOC） mineralization and its relationship with soil temperature, soil water content, soil depth and altitude in Qilian Mountains were analyzed by soil incubation in an orthogonal experiment. The impacts of soil temperature and soil depth on the cumulative SOC mineralization and its ratio were higher than that of soil water content, while the impacts of altitude were not significant. The cumulative SOC mineralization and its ratio were higher at 35℃ than at 5, 15, or 25℃, while the differences between these three temperatures were not significant. SOC was higher in a soil water content of 30% or 40% than in 10% or 20%, but the differences between 30% and 40% or between 10% and 20% were not significant. SOC was higher in the 0-15 cm than in the 15-35 cm soil depth. The difference between different altitudes was not significant. The SOC mineralization rate and its ratio declined with increasing incubation time. The impacts of soil temperature and depth on the rate and its ratio of SOC mineralization were higher than the impacts of soil water content on them. The impacts of altitude were not significant. The rate and its ratio of SOC mineralization was higher at 35℃ than at 5, 15, or 25℃, especially within 20 d of incubation. They were higher in soil water contents of 30% or 40% than in 10% or 20%, but the difference between 30% and 40% or between 10% and 20% were not significant, especially within 20 d of incubation. They were higher in the 0- 15 cm than in the 15-35 cm soil depth. There was no significant difference between different altitudes. The first-order rate kinetic function fitted SOC mineralization well （R^2〉0.95）. Based on cumulative SOC mineralization and the decomposition coefficient, the labile SOC pool was lowest at 5℃ and the decomposition coefficient was highest at 35℃, and the labile SOC pool was lower at 25℃ than at other temperatures. Based on the fraction of SOC mineralization, the labile SOC pool increased at higher temperatures and the decomposition coefficient at 350C was lower than at 15 or 25℃, which were lower than at 5℃. The Ql0 indicated that the SOC mineralization rate increased with time and with every 10℃ increase. Based on the rate of SOC mineralization or its fraction, Q10 was 1-6 from 5 to 15℃ and 1-2 from 15 to 25℃. Based on the SOC mineralization rate, Ql0 was 2-4 from 25 to 35℃ but based on the fraction of SOC mineralization rate, Q10 was 1.5-3, 0 from 25 to 35℃. This study indicated that the mineralization of surface SOC under alpine meadows in Qilian Mountain would be greatly influenced by temperature change.