Evolution of atmospheric carbon dioxide concentration at different temporal scales recorded in a tall forest

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• 作者：Jiabing Wu ; Dexin Guan ; Fenhui Yuan ; Hong Yang ; Anzhi Wang ; Changjie Jin
• 关键词：Carbon dioxide ; Greenhouse gas ; CO2 concentration ; Temperate forest
• 刊名：Atmospheric Environment
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：61
• 期：Complete
• 页码：9-14
• 全文大小：503 K

文摘

Understanding the temporal evolution of CO₂ over specific ecosystems can provide additional insight into atmospheric CO₂ variability. From 2003 to 2010, CO₂ ambient concentrations in an old-growth temperate forest were measured continuously by using an infrared analyzer. The results show that daily cycle and seasonal variation of CO₂ were mostly dominated by vegetation activity, whereas the weak turbulent mixing at night contributed frequently to CO₂ build-up below the canopy. As a result, CO₂ concentrations changed considerably during daytime and nighttime in the forest stand. The monthly means exhibited a seasonal variation characterized by a primary peak in December and a minimum during July to August, with an average seasonal amplitude (the difference of minimum and maximum monthly means) of 60.5?ppmv. By fitting a harmonic model to the monthly means, linear increase trends of 1.7?ppmv?yr^?1 in the annual mean CO₂ concentrations and 0.58?ppmv?yr^?1 in the amplitude of the seasonal cycle were estimated. The upward trend of annual mean CO₂ concentration may be attributed to the dramatic global increase in CO₂ emissions during the study period. This study also found that the stratification of CO₂ concentrations below the canopy during nighttime was easily disrupted after sunrise, which suggests that forest floor plants are not, as previous assumed, exposed to significantly greater CO₂ concentrations than the normal atmospheric concentrations.