祁连山中部四种典型生态系统土壤有机碳矿化及其影响因素

Soil organic carbon mineralization and its affecting factors under four typical vegetations in mid Qilian Mountains

以正交试验培养土壤探讨了祁连山4种典型生态系统土壤有机碳矿化及其与温湿度的关系。结果表明:温度对土壤有机碳累积矿化量及其比例影响显著(P<0.05)。就土壤有机碳累积矿化量,35℃和25℃比5℃下高(P<0.05);土壤培养14d,10%含水量下为最低,山地森林土壤比荒漠草原和干草原高,高寒草甸比荒漠草原高(P<0.05)。就土壤有机碳矿化比例,35℃和25℃比5℃下高,35℃比15℃下高(P<0.05);荒漠草原和干草原比山地森林和高寒草甸低(P<0.05)。土壤有机碳矿化速率及其比例随培养时间延长而递减。温度和生态系统类型对土壤有机碳矿化速率及比例影响显著(P<0.05)。就土壤有机碳矿化速率,25℃和35℃比5℃下高(P<0.05);土壤培养0～4d和6～10d,10%含水量下最低,高寒草甸和山地森林比荒漠草原高(P<0.05)。就土壤有机碳矿化速率比例,25℃和35℃比5℃下高,35℃比15℃下高;山地森林和高寒草甸比荒漠草原和干草原中高(P<0.05)。一阶动态方程拟合土壤有机碳矿化动态效果较好(R2>0.95)。表明祁连山4种典型生态系统土壤有机碳分解受温度变化影响较大。

To understand the effects of varying soil temperature and moisture content on soil organic carbon （SOC） mineralization under mountain forest, alpine meadow, desert steppe, and arid steppe in mid Qilian Mountains, an anaerobic incubation test with orthogonal design was conducted in an artificial climatic chamber. The results showed that the cumulative amount of mineralized SOC was higher at 35 ℃ or 25 ℃ than at 5 ℃, and was the lowest at soil moisture content of 10%. The soil under mountain forest had the highest cumulative amount of mineralized SOC, followed by that under alpine meadow, and under desert steppe or arid steppe. The SOC mineralization rate was significantly higher at 35 ℃ or 25 ℃ than at 5 ℃, and at 35 ℃ than at 15 ℃, and lower under desert steppe and arid steppe than under mountain forest and alpine meadow. The cumulative amount of mineralized SOC as well as the SOC mineralization rate decreased with incubation time, and the effects of soil temperature and ecosystem type on them were significant （P 〈 0. 05 ）. It was considered that soil temperature was the dominant factor affecting the SOC mineralization under the mountain forest, alpine meadow, desert steppe, and arid steppe in mid Qilian Mountains, and the dynamics of the SOC mineralization could be better fitted by first order equation.