鄂南4种典型土地利用方式红壤CO_2排放及其影响因素

CO_2 Fluxes from Red Soil Under Four Land Use Types in Mid-Subtropical,China

以湖北省咸宁地区分布的红壤为研究对象,采用静态箱法对4种典型土地利用方式(水稻-油菜轮作田,旱地,林地,果园)土壤CO2的排放特征及其相关影响因子进行了观测研究.结果表明,4种利用方式土壤CO2的年排放总量从高到低分别为水稻-油菜轮作田1129 g/(m2.a),果园828 g/(m2.a),旱地632 g/(m2.a),林地533 g/(m2.a).土壤CO2排放通量呈现明显的季节性变异,水田夏季淹水期排放低,而其它3种土壤都是夏季最高,春秋次之,冬季最低,并与对应的大气温度、土壤温度变化趋势基本一致.其中5 cm地温与4种土壤CO2排放通量均成极显著的相关关系,且以林地的相关性最大.除水田外,其它土壤CO2排放通量与大气温度均呈显著正相关关系.根据5 cm地温与CO2排放通量的相关方程计算得出,4种利用方式红壤的Q10分别为水田1.51,果园1.88,林地2.08,旱地2.7.土壤CO2排放通量与土壤WFPS之间并没有明显的相关关系.土壤可溶性有机碳(DOC)含量与CO2排放通量的变化趋势基本一致,且DOC在降水或淹水的情况下显著增大.

CO2 fluxes from red soil under different land use （paddy, upland, woodland and orchard） were measured at Xianning city, Hubei province with closed chamber method. The results showed that the annual CO2 emission were 1 129, 632, 533, and 828 g/（m2 ·a） for paddy, upland, woodland, and orchard respectively. Soil CO2 fluxes revealed seasonal fluctuations, with the tendency that maximum value was in summer, minimum was in winter and intermediate in spring and autumn except for paddy soil. CO2 fluxes for paddy soll were significantly higher than the other soils except it was submerged. An exponential relationship between soil CO2 fluxes and soll temperature at 5cm depth could be received. Air temperature also had significant positive correlation with soil CO2 fluxes except for paddy soil. The Q10 values were 1.51 （paddy）, 1.88（orchard）, 2.08（woodland）, 2.7（upland） respectively based on the exponential equation between soil CO2 fluxes and soil temperature. The results indicated that there was no significant correlation between CO2 fluxes and soil moisture. In addition, DOC had the same seasonal tendency as CO2 fluxes, and it increased when soil was irrigated or rained.