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千烟洲中亚热带人工林生态系统受典型亚热带大陆性季风气候影响,其特点是年水热资源丰富,但是夏季水热资源分布明显不同步,经常受到季节性高温干旱胁迫的影响．作为中国陆地生态系统通量观测研究网络(ChinaFLUX)的组成部分,利用涡度相关技术对千烟洲人工林生态系统CO2通量进行了长期连续的观测．本研究基于2003和2004年月尺度的净生态系统生产力(NEP)、生态系统呼吸(Re)和总生态系统生产力(GEP)数据,初步分析和探讨了季节性干旱对生态系统碳吸收的影响．结果表明,2003和2004年该生态系统的碳吸收都呈现双峰曲线式的季节变化模式．生态系统碳平衡的两个组分Re和GEP的耦合关系决定了生态系统的碳吸收特征．生态系统碳吸收的降低程度取决于季节性干旱期间温度升高和降水量减少的耦合程度．Re和GEP都会受到干旱胁迫的影响,但是响应的方式与程度有所不同,是造成森林生态系统源／汇强度变化的根本原因．
Affected by the typical subtropical continental monsoon climate, Qianyanzhou subtropical plantation ecosystem is characterized by rich annual water and heat resources, but the distribution of water and heat resources is obviously out of sync in summer and is often affected by seasonal high temperature and drought stress. As part of the China Terrestrial Ecosystem Flux Observational Research Network (ChinaFLUX), long-term continuous CO2 fluxes of plantation ecosystem in Qianyanzhou were observed using the eddy covariance technique. Based on the monthly NEP, E and GEP data of 2003 and 2004, this study initially analyzed and explored the effects of seasonal drought on ecosystem carbon uptake. The results showed that the carbon uptake of the ecosystem in 2003 and 2004 presented a bimodal seasonal variation pattern. The coupling of Re and GEP, the two components of the ecosystem carbon balance, determines the carbon uptake of the ecosystem. The extent to which ecosystem carbon uptake is reduced depends on the degree of coupling between temperature rise and precipitation reduction during seasonal droughts. Both Re and GEP will be affected by drought stress, but the way of responding is different from the degree of drought, which is the root cause of the change of source intensity of forest ecosystem.