三江源区高寒草原不同退化程度对土壤呼吸的影响

摘要

以高寒草原土壤呼吸为研究对象,探讨了高寒草原退化程度对土壤呼吸的影响及不同退化程度高寒草原土壤呼吸基本特征。结果表明,随着高寒草原退化程度的加剧,土壤CO2释放速率呈下降趋势,不同退化程度间土壤CO2释放速率差异达极显著水平,变化范围为3.89~6.24 g∕(m2•d)；不同退化程度高寒草原土壤CO2释放速率呈明显的日变化特征,土壤CO2释放速率在14：00时达到一天中的最大值,在凌晨2：00时达到一天中的最小值,土壤CO2释放速率白天大于夜晚,不同退化程度下土壤CO2释放速率在一天中各时刻基本呈未退化(UD)>轻度退化(LD)>中度退化(MD)>高度退化(HD)>极度退化(ED)的变化趋势,土壤CO2释放速率日动态与5 cm土壤温度的日动态变化趋势一致；在土壤温度和土壤湿度对土壤呼吸影响的双因素模型中,温度反应系数的变化范围为0.114~0.163,湿度反应系数的变化范围为0.486~1.629,拟合模型R2为0.860~0.888,且呈ED>HD>MD>LD>UD的变化趋势,不同退化程度高寒草原Q10变化范围为2.888~3.493。%The influences of alpine steppe degradation on soil respiration and basic characteristics of soil respiration of different degradation degree were studied. The results showed that soil CO2 emission rate was decreased with the increase of degradation degree. Among different degradation degree, soil CO2 emission rates were significantly different (P<0.01), ranged from 3.89 g∕(m2•d) to 6.24 g∕(m2•d). Alpine steppe soil CO2 emission rate of different degradation degree had obvious diurnal variation characteristics such as soil CO2 emission rate achieved maximum value at 14:00 and minimum value at 2:00 in a day. Soil CO2 emission rate in the day was greater than that of the night. The changing trend of soil CO2 emission rate of different degradation degree in every moment of the day is UD>LD>MD>HD>ED. The day dynamic changing trend of soil CO2 emission rate was consistent with 5 cm layer soil temperature. Soil temperature and soil moisture were important factors influencing alpine steppe soil respiration rate. The value of soil respiration two-factors model ranged from 0.114 to 0.163, and c value ranged from 0.486 to 1.629, fitting model R2 ranged from 0.860 to 0.888, and showed ED>HD>MD>LD>UD. Alpine steppe Q10 value of different degradation degree ranged from 2.888 to 3.493.