太湖流域典型稻麦轮作农田生态系统碳交换及影响因素  

Analysis of net ecosystem CO_2 exchange( NEE) in the rice-wheat rotation agroecosystem of the Lake Taihu Basin,China

作　　者：徐昔保[1] 杨桂山[1] 孙小祥[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所,流域地理学重点实验室,南京210008

出　　处：《生态学报》2015年第20期6655-6665,共11页Acta Ecologica Sinica

基　　金：国家自然科学基金重点项目(41030745);国家自然科学基金(41101565,41371532);中国科学院南宁地理与湖泊研究所“135”学科前沿项目(NIGLAS2012135019);江苏省自然科学基金(BK2011882)

摘　　要：利用涡度相关技术观测太湖流域典型稻麦轮作农田生态系统2a净生态系统碳交换(NEE)变化过程,分析其碳交换特征及影响机理,结果表明:太湖流域典型稻麦轮作农田年NEE为-749.49—-785.38 g C m-2a-1,考虑作物籽粒碳和秸秆还田后净吸收88.12 g C m-2a-1,为弱碳汇;稻/麦季日均NEE和白天NEE季节变化直接受作物植被生长影响;麦季夜间NEE与10 cm土壤温度呈显著指数关系,2012/2013年温度敏感系数(Q10)分别为3.03和2.67;当土壤水分低于田间持水量时,麦季夜间NEE主要受土壤温度影响,反之,夜间NEE受土壤温度和水分双重影响;降水对麦季夜间NEE有短时的激发效应;稻季淹水对土壤呼吸产生较明显的阻滞效应,降低了夜间NEE对土壤温度的敏感性,2012和2013年分别为1.88和1.39,稻季淹水与烤田交替变化对土壤呼吸产生明显的抑制或激发的短时效应。The agroecosystem plays an important role in global and regional carbon balance due to its large area and high carbon sequestration potential. Due to limitations in observation techniques and the spatial heterogeneity of the environment,net ecosystem CO2exchange（ NEE） in the rice-wheat rotation system of the Lake Taihu Basin remains poorly understood. This paper aimed to investigate NEE in this agroecosystem based on observations of CO2 flux with the eddy covariance technique,from December 2011 to November 2013. Annual carbon balance was estimated from observed NEE and carbon contents of grain and straw. Half-hourly flux data were first corrected by removal of anomalous data points,coordinate rotation,frequency loss correction,and WPL correction. Two neural network models for daytime and nighttime NEE gap-filling were built. The results showed that annual daytime and nighttime NEE was- 749. 49 g C m- 2a- 1and-785. 38 g C m- 2a- 1,respectively. Accounting for grain removal and return of straw to the field,total net C absorption was88. 12 g C m- 2a- 1,characterizing the agroecosystem as a weak carbon sink. This carbon sequestration capacity is greater than those of the Huaihe River Basin,subtropical region,and north China plain. Diurnal NEE exhibited a typical ＂ W＂ bimodal seasonal pattern,and both seasonal NEE and average monthly diurnal NEE showed significant annual fluctuations.Cumulative diurnal NEE ranged from- 12. 88 g C m- 2d- 1to 5. 94 g C m- 2d- 1,with a mean of- 2. 10 g C m- 2d- 1.Maximum cumulative diurnal NEE occurred in the wheat season of each year,with values of- 12. 88 g C m- 2d- 1on April26,2012 and- 11. 62 g C m- 2d- 1on April 11,2013,respectively. Variation in diurnal NEE and daytime NEE in the rice-wheat season was significantly correlated with crop height,suggesting that diurnal NEE and daytime NEE were both influenced by crop growth. Nighttime NEE and soil temperature at 10 cm during the wheat season exhibit a significant exponential relationship,with a temperature sensitivity coeffici

关 键 词：农田生态系统 碳交换 稻麦轮作 涡度相关 太湖流域 

分 类 号：S181[农业科学—农业基础科学]