Journal of Food, Agriculture and Environment

Responses of ecosystem CO₂ fluxes to rainfall events in rain-fed winter wheat agro-ecosystem

Author(s):

Wen Wang, Yuncheng Liao *, Qiang Gu

Recieved Date: 2012-10-12, Accepted Date: 2013-01-14

Abstract:

Winter wheat is one of the major food crops in the Chinese Loess Plateau, accounting for about 30% of the total crop area. To better explain the mechanistic relationship between carbon cycle and climate change, long-term eddy covariance measurements were performed in the rain-fed winter wheat agro-ecosystem during three growing seasons (2008-2010). The results showed that the 2009 growing season received more rainfall and had more frequent dry-wet cycles, which resulted in the higher ecosystem CO₂ fluxes, whereas the 2008 growing season had considerably lower levels of ecosystem CO₂ fluxes. Furthermore, the daily CO₂ fluxes were significantly affected by the effective rainfall events (daily rainfall > 5 mm). The daily ecosystem respiration (R_eco) reached the peaks within 1–2 days after the effective rainfall events, which were about 1- to 4-fold larger than that in the pre-rain days. The maximum daily net ecosystem CO₂ exchange (NEE) occurred 3-6 days after the effective rainfall events, which were about 0.5- to 1.5-fold larger than that in the pre-rain days. We found the daily R_eco and NEE at 7 days after the effective rainfall events were 17% and 23% higher than that at the pre-rain days, respectively, however, the daily NEE and R_eco at 7 days after the small rainfall events (daily rainfall d ≤ 5 mm) were 9% and 4% lower than that at the pre-rain days, respectively. The result of regression analysis suggested that the antecedent soil water content (SWC) played a more important role than the rainfall amount in regulating pulse response of CO₂ fluxes in the water-limited ecosystem. 

Keywords:

Net ecosystem CO₂ exchange, ecosystem respiration, rainfall event, rain-fed winter wheat agro-ecosystem, antecedent soil water content

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Journal: Journal of Food, Agriculture and Environment
Year: 2013
Volume: 11
Issue: 1
Category: Environment
Pages: 982-986

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