科尔沁沙丘-草甸梯级生态系统土壤温室气体通量特征及其影响因素

Characteristics of soil greenhouse gas flux and its driving factors in Horqin sand dune-meadow wetland cascade ecosystems

采用静态箱-气相色谱法,对科尔沁半干旱地区典型的沙丘-草甸梯级生态系统中半流动沙丘和草甸湿地的温室气体(CO2、CH4、N2O)通量进行了观测,分析了生长季温室气体的动态变化及其与环境影响因子的关系.结果表明:生长季半流动沙丘和草甸湿地CH4通量均整体表现为吸收,平均值分别为-52.7和-34.7μg·m-2·h-1,介于-176.1~49.8μg·m-2·h-1之间变化,8月22日半流动沙丘CH4吸收值达到生长季最大值;8、9月降雨集中时段内草甸湿地CH4通量表现为持续排放,与半流动沙丘呈明显差异.N2O通量在7月21日达到生长季最大值,半流动沙丘N2O通量的月均值表现为7月>8月>9月>6月>5月.土壤温湿度是影响CO2和CH4通量的关键因子,N2O通量主要受土壤温度的影响.样地土壤温度敏感性(Q10)表现为半流动沙丘(1.009)<草甸湿地(1.474),半流动沙丘土壤受到水分胁迫,导致其温室气体通量对土壤温度变化的敏感性明显低于草甸湿地.

Using the static chamber-GC technique,greenhouse gas(CO2,CH4,N2O)fluxes of sand dunes and meadow wetlands were measured in a typical sand dune-meadow cascade ecological zone of Horqin.The dynamics of the greenhouse gas fluxes and driving factors were analyzed.The results showed that soil CH4 flux underwent absorption during the growing season,with average CH4 fluxes of semi-mobile dunes and meadow wetlands were-52.7μg·m-2·h-1 and-34.7μg·m-2·h-1,respectively,ranging from-176.1 to 49.8μg·m-2·h-1.The peak of CH4 absorption in the growing season occurred at August 22 nd,2017.In August and September,the months with heavy rainfall,the CH4 flux in meadow wetlands showed continuous emission,being significantly different from that in semi-mobile dunes.The peak of N2O flux during the growing season was at July 21 st.The monthly average N2O flux in semi-mobile dunes was following the order of July>August>September>June>May.Soil temperature and moisture were the key factors affecting CO2 and CH4 fluxes,whereas the N2O flux was mainly affected by soil temperature.The soil temperature sensitivity(Q10)showed the sequence of semi-mobile dune(1.009)<meadow wetland(1.474).The water stress rendered the greenhouse gas fluxes in semi-mobile dunes being less sensitive to soil temperature change than that in meadow wetlands.