寒温带兴安落叶松林土壤温室气体通量的时间变异

采用静态箱/气相色谱(GC)法,对寒温带兴安落叶松林区6-9月生长季土壤CO2、CH4和N2O通量进行原位测定,研究了土壤温室气体通量的季节和昼夜变化及其与环境因子的关系.结果表明:在生长季,兴安落叶松林土壤为大气CH4的汇,吸收通量为22.3～107.8 μg CH4-C·m-2·h-1,6-9月月均甲烷吸收通量为(34.0±7.1)、(71.4±9.4)、(86.3±7.9)和(40.7-±6.2) μg·m-2·h-1；不同季节土壤CH4昼夜通量的变化规律相同,一天中均在10:00达到最大吸收高峰.土壤CO2日通量呈明显的双峰曲线,月均CO2通量大小顺序为7月＞8月＞6月＞9月.土壤N2O通量变异较大,在-9.1 ～31.7μg·m-2·h-1之间.土壤温度和湿度是影响CO2和CH4通量的重要因子,N2O通量主要受温度的影响.在兴安落叶松林区,10:00左右观测获得的温室气体地-气交换通量,经矫正后可以代表当日气体通量.

Temporal variation of soil greenhouse gases fluxes in a cold-temperate Larix gmelinii forest in Inner Mongolia,China

By using static chamber-gas chromatograph technique,an in situ measurement was conducted on the soil CH4,CO2,and N2O fluxes in a cold-temperate Larix gmelinii forest in Inner Mongolia from June to September 2007,aimed to understand the diurnal and seasonal variations of soil greenhouse gasses fluxes and their relations with the associated environmental factors in L.gmelinii forests in cold-temperate zone.In growth season,the soil in the L.gmelinii forest was the sink of atmospheric CH4,with the flux ranged from 22.3 to 107.8 μg CH4-C·m-2·h-1.The mean monthly uptake of CH4 in June,July,August,and September was 34.0±7.1,71.4±9.4,86.3±7.9,and 40.7±6.2 μg·m-2·h-1,respectively.The mean diurnal flux of soil CH4 from June to September showed the same variation trend,i.e.,peaked at 10:00 am.The diurnal variation of soil CO2 flux showed an obvious double-peak,and the mean monthly CO2 flux was in the order of July>August>June> September.Soil N2O flux varied dramatically from-9.1 to 31.7 μg·m-2·h-1.Soil temperature and humidity were the main factors affecting the CH4 and CO2 fluxes,and soil temperature mainly affected the N2O flux.In the L.gmelinii forest,the CH4,CO2,and N2O fluxes measured at 10:00 am could represent the diurnal CH4,CO2,and N2O fluxes on the same day.