淮河流域稻麦轮作农田生态系统CO2通量多时间尺度变化特征

Multi-Time Scale Variation of Net Ecosystem CO2 Flux over Rice-wheat Rotation Agroecosystem in Huaihe River Basin

为了准确评价农田生态系统在区域碳平衡中的作用,采用涡度相关技术对淮河流域典型稻麦轮作农田生态系统CO2通量进行了长期连续观测。基于数据质量控制后的寿县国家气候观象台2007年7月—2019年12月CO2通量观测资料,分析了淮河流域稻麦轮作农田生态系统不同时间尺度CO2通量的变化特征。结果表明:淮河流域稻麦轮作农田生态系统CO2通量具有明显的日变化、季节变化和年际差异。多年平均CO2通量日变化为U型特征,白天为净吸收,最大值在12时,夜间为净排放,最大值在21时30分,白天净吸收量明显多于夜间净排放量。多年平均CO2通量季节变化为W型双峰特征,1—5月、7—10月和12月为CO2净吸收,4月和8月为次大值和最大值;6月和11月为净排放。不同生育期CO2通量差异显著,小麦和水稻孕穗期CO2净吸收均最大,分别为-0.207 mg/(m^2·s)和-0.266 mg/(m^2·s)。寿县稻麦轮作农田生态系统具有强固碳能力,2007—2019年平均的年CO2净吸收量为−2.58 kg/(m^2·a)。CO2净吸收量年际差异大,2008年最大,为-3.26 kg/(m^2·a);2017年最小,仅为-1.78 kg/(m^2·a)。整个生育期CO2净吸收总量为-2.8 kg/m^2,小麦和水稻分别占43.2%和56.8%。稻麦轮作两个间歇期CO2净排放量为0.21 kg/m^2。

For accurately evaluating the role of agroecosystem in regional carbon balance,the CO2 flux of typical rice-wheat rotation agroecosystem was continuously observed for a long time by using vorticity correlation technology in Huaihe River Basin.Based on the observation data of CO2 flux of Shouxian National Climate Observatory from July 2007 to December 2019 after data quality control,the variation characteristics of CO2 flux in different time scales of rice-wheat rotation agroecosystem in Huaihe River Basin was analyzed.The results showed that there were obvious diurnal,seasonal and interannual variations in CO2 flux of that in Huaihe River Basin.The diurnal variation of CO2 flux shows a U-shaped feature,with net absorption in the daytime,maximum at 12:00 BT,and net emission at night,maximum at 21:30 BT.The net absorption in the daytime is significantly higher than the net emission at night.The seasonal variation of CO2 flux shows a W-shaped double peak feature.The net absorption of CO2 is from January to May,July to October and December,and reaches the second maximum in April and the maximum in August;the net emission is from June and November.The net CO2 uptake of wheat and rice at booting stage was−0.207 mg/(m^2·s)and−0.266 mg/(m^2·s)respectively.The rice-wheat rotation agroecosystem in Shouxian has strong carbon sequestration capacity,and the annual average net CO2 absorption from 2007 to 2019 is−2.58 kg/(m^2·a).The annual difference is large.In 2008,the net absorption of CO2 is the largest,−3.26 kg/(m^2·a).In 2017,the net absorption of CO2 is the smallest,only−1.78 kg/(m^2·a).During the whole growth period,the total net CO2 uptake was−2.8 kg/m^2,accounting for 43.2%of wheat and 56.8%of rice,respectively.The net CO2 emission of rice-wheat rotation in two intermittent periods was 0.21 kg/m^2.