Journal of Integrative Agriculture ›› 2013, Vol. 12 ›› Issue (1): 147-158.DOI: 10.1016/S2095-3119(13)60215-4

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Seasonal and Annual Variations of CO2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

 WANG Wen, LIAO Yun-cheng , GUO Qiang   

  1. College of Agronomy, Northwest A&F University, Yangling 712100, P.R.China
  • 收稿日期:2012-06-21 出版日期:2013-01-01 发布日期:2013-01-24
  • 通讯作者: Correspondence LIAO Yun-cheng, Tel: +86-29-87082990, Fax: +86-29-87082845, E-mail: yunchengliao@nwsuaf.edu.cn
  • 作者简介:WANG Wen, Tel: +86-29-87082990, E-mail: wangwen200806@yahoo.com.cn
  • 基金资助:

    This study was supported by the National Natural Science Foundation of China (31171506 and 31071375).

Seasonal and Annual Variations of CO2 Fluxes in Rain-Fed Winter Wheat Agro-Ecosystem of Loess Plateau, China

 WANG Wen, LIAO Yun-cheng , GUO Qiang   

  1. College of Agronomy, Northwest A&F University, Yangling 712100, P.R.China
  • Received:2012-06-21 Online:2013-01-01 Published:2013-01-24
  • Contact: Correspondence LIAO Yun-cheng, Tel: +86-29-87082990, Fax: +86-29-87082845, E-mail: yunchengliao@nwsuaf.edu.cn
  • About author:WANG Wen, Tel: +86-29-87082990, E-mail: wangwen200806@yahoo.com.cn
  • Supported by:

    This study was supported by the National Natural Science Foundation of China (31171506 and 31071375).

摘要: To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO2 exchange (NEE) was (-71.6±5.7) and (-65.3±5.3) g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink (117.4-126.2 g C m-2 yr-1). However, after considering the harvested grain, the agroecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration (Reco) were sensitive to changes in soil water content (SWC). When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation (PAR), and a highly significant relationship between Reco and soil temperature (Ts). However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the Reco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily Reco, whereas the Reco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated Reco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

关键词: CO2 flux , carbon sequestration , soil water content , rainfall event , rain-fed winter wheat agro-ecosystem

Abstract: To accurately evaluate the carbon sequestration potential and better elucidate the relationship between the carbon cycle and regional climate change, using eddy covariance system, we conducted a long-term measurement of CO2 fluxes in the rain-fed winter wheat field of the Chinese Loess Plateau. The results showed that the annual net ecosystem CO2 exchange (NEE) was (-71.6±5.7) and (-65.3±5.3) g C m-2 y-1 for 2008-2009 and 2009-2010 crop years, respectively, suggesting that the agro-ecosystem was a carbon sink (117.4-126.2 g C m-2 yr-1). However, after considering the harvested grain, the agroecosystem turned into a moderate carbon source. The variations in NEE and ecosystem respiration (Reco) were sensitive to changes in soil water content (SWC). When SWC ranged form 0.15 to 0.21 m3 m-3, we found a highly significant relationship between NEE and photosynthetically active radiation (PAR), and a highly significant relationship between Reco and soil temperature (Ts). However, the highly significant relationships were not observed when SWC was outside the range of 0.15-0.21 m3 m-3. Further, in spring, the Reco instantly responded to a rapid increase in SWC after effective rainfall events, which could induce 2 to 4-fold increase in daily Reco, whereas the Reco was also inhibited by heavy summer rainfall when soils were saturated. Accumulated Reco in summer fallow period decreased carbon fixed in growing season by 16- 25%, indicating that the period imposed negative impacts on annual carbon sequestration.

Key words: CO2 flux , carbon sequestration , soil water content , rainfall event , rain-fed winter wheat agro-ecosystem