Abstract: Carbon fluxes variation rule of field ecosystem and source sink relationship is a hot topic for study in the international carbon cycle. In order to expound the characteristics of carbon fluxes variations and its influencing factors in tobacco field ecosystem during tobacco harvesting stage, this paper measured the carbon emission fluxes from flue-cured tobacco field in harvest period under 2 different fertilizer treatments （NPK and NPKOM）by closed chamber-infrared method. The results showed that carbon fluxes in tobacco field ecosystem changed from assimilation to emission and mainly showed in carbon assimilation during the observation period. Carbon fluxes in NPKOM treatment were significantly higher than that in NPK treatment, especially in the middle of harvest period. The maximum net carbon assimilation was appeared after harvest. And the value in NPK and NPKOM treatments were 79.2 mg/m2·h and 81.8 mg/m2·h, separately. Judging from the entire harvest period, all environmental temperature variables (air temperature, surface temperature, 5 cm and 10 cm soil temperature) were significantly correlated with each other, while the soil humidity was extreme significant negatively correlated with surface soil temperature and air temperature. Carbon fluxes were significantly or extreme significantly correlated with soil surface temperature, 5 cm and 10 cm soil temperatures, air temperature and soil humidity. And 5 cm and 10 cm soil temperature were the dominant factors among all environmental factors affecting carbon flux in tobacco ecosystem during the mature stage by principal component analysis. We also found that the carbon fluxes in tobacco field ecosystem present a “W” type fluctuation in harvest period. Meanwhile, the carbon fluxes were significantly correlated with the number of effective tobacco leaves by parabolic relationship.

Key words: flue-cured tobacco field, harvest period, ecosystem, carbon flux, closed chamber technique

摘要： 农田生态系统碳通量的变化规律及源汇关系是国际碳循环的研究热点，为阐明烟田生态系统在烟叶采收期的碳通量变化特征及影响因素，在湖北恩施烟区利用静态箱-红外二氧化碳分析仪法对纯化肥（NPK）和化肥与有机肥配施（NPKOM）两种处理的烟田碳通量进行了动态监测。结果表明：在烟草采收期，烟田碳通量由碳吸收向碳排放转变，整体表现为碳吸收，NPKOM的碳通量显著高于NPK处理，特别在采收中段表现更明显。最大碳排放量出现在全部采收后，NPK和NPKOM处理的碳通量分别为79.2 mg/m2·h和81.8 mg/m2·h。从整个采收期来看，各温度因子间存在显著或极显著的相关性，其中5 cm地温与10 cm地温相关性最高，土壤湿度与地表温度、气温呈极显著负相关。烟田生态系统碳通量与地表温度、5 cm地温和10 cm地温、土壤湿度和气温均有显著相关性。主成分分析表明，5 cm及10 cm地温是影响该时期碳通量的主要环境因子。采收期烟田生态系统碳通量呈现“W”型波动，同时碳通量与烟株的有效叶片数呈极显著的抛物线型关系。

关键词: 烟田, 采收期, 生态系统, 碳通量, 静态箱法