风沙采煤沉陷区地表生物结皮土壤碳排放对水热因子变化的响应

Response of soil carbon emission of biological crust to hydrothermal factors in mining subsidence area in aeolian

生物结皮是干旱区土壤碳排放的重要参与者,为阐明毛乌素沙地采煤沉陷区典型生物结皮土壤碳排放规律及其对土壤水热因子变化的响应,以藓类结皮、藻类结皮和地衣结皮为研究对象,通过Automated Soil CO2 Exchange Station(简称ACE)土壤碳通量自动监测系统分别测定了3类生物结皮土壤碳排放速率、土壤温湿度,并对2者关系进行探究。结果表明:①3类生物结皮土壤碳排放速率的日变化特征曲线总体上均呈现“不对称钟形”的“单峰”曲线特征,峰值在12:00~13:00。土壤碳排放速率日均值由大到小依次为藻类结皮(0.47μmol/(m^(2)·s))>藓类结皮(0.45μmol/(m^(2)·s))>地衣结皮(0.44μmol/(m^(2)·s));②3类生物结皮的土壤碳排放速率与表层土壤温度均呈现二次函数关系,其决定系数分别为0.59,0.46和0.64(P<0.01);③生物结皮土壤碳排放速率与表层土壤含水量均呈二次函数关系,其中藓类结皮的决定系数R2达到了0.45的极显著水平(P<0.01);④土壤含水量与土壤温度可以较好地解释土壤碳排放速率,拟合方程中2者对于土壤碳排放速率的解释度均在57.8%以上。本研究可为采煤沉陷区生态修复过程中碳汇(源)及碳平衡估算提供数据支撑。

Soil carbon emission of the lands covered by biocrusts is an important component in the carbon cycle.To clarify the carbon emission pattern of typical biocrusts in the coal mining subsidence area of Mawwusu sand and its response to changes in soil hydrothermal factors,the soil carbon emission rate,soil temperature and humidity were measured by the Automated Soil CO2 Exchange Station(ACE),and the relationship between them was explored.The results show that:①on the whole,the diurnal variation characteristic curves of soil carbon emission rates of three typical biologically-crusted soils generally show the characteristics of asymmetrical bell single peak’curve,with the peak value between 12:00-13:00.The daily average soil carbon emission rate order is algae overlying crust(0.47μmol/(m^(2)·s))>moss overlying crust(0.45μmol/(m^(2)·s))>lichen crust(0.44μmol/(m^(2)·s)).②The soil respiration rate of three typical biologically-crusted soils shows a quadratic function relationship with the surface soil temperature,and their determination coefficients are 0.59,0.46 and 0.64,respectively,all of which reach extremely significant positive correlation levels(P<0.01).③The relationship between soil carbon emission rate and surface soil water content is quadratic function,and the best fitting relationship between the soil water content of moss overlying soil is quadratic function,and its coefficient R2 reaches a very significant level of 0.45(P<0.01).④Soil moisture content and soil temperature could better explain the soil carbon emission rate,and both of which could explain the soil respiration rate more than 57.8%in the fitting equation.The findings can provide data support for the estimation of carbon sink(source)and carbon balance in the ecological restoration process of mining subsidence area.