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	Biophysical Controls on Light Response of Net CO2 Exchange in a Winter Wheat Field in the North China Plain
	Li J.; Li J.; Yu Q.
	2014
关键词	carbon-dioxide exchange environmental controls ecosystem exchange blue-light tower measurements diffuse-radiation temperate forest sky conditions mixed forest photosynthesis
英文摘要	To investigate the impacts of biophysical factors on light response of net ecosystem exchange (NEE), CO2 flux was measured using the eddy covariance technique in a winter wheat field in the North China Plain from 2003 to 2006. A rectangular hyperbolic function was used to describe NEE light response. Maximum photosynthetic capacity (P-max) was 46.6 +/- 4.0 mu mol CO2 m(-2) s(-1) and initial light use efficiency (alpha) 0.059 +/- 0.006 mu mol mu mol(-1) in April-May, two or three times as high as those in March. Stepwise multiple linear regressions showed that Pmax increased with the increase in leaf area index (LAI), canopy conductance (g(c)) and air temperature (T-a) but declined with increasing vapor pressure deficit (VPD) (P<0.001). The factors influencing Pmax were sorted as LAI, g(c), T-a and VPD. alpha was proportional to ln(LAI), g(c), T-a and VPD (P<0.001). The effects of LAI, gc and Ta on a were larger than that of VPD. When Ta>25 degrees C or VPD>1.1-1.3 kPa, NEE residual increased with the increase in Ta and VPD (P<0.001), indicating that temperature and water stress occurred. When g(c) was more than 14 mm s(-1) in March and May and 26 mm s(-1) in April, the NEE residuals decline disappeared, or even turned into an increase in g(c) (P<0.01), implying shifts from stomatal limitation to non-stomatal limitation on NEE. Although the differences between sunny and cloudy sky conditions were unremarkable for light response parameters, simulated net CO2 uptake under the same radiation intensity averaged 18% higher in cloudy days than in sunny days during the year 2003-2006. It is necessary to include these effects in relevant carbon cycle models to improve our estimation of carbon balance at regional and global scales.
出处	Plos One
卷	9
期	2
收录类别	SCI
语种	英语
ISSN号	1932-6203
内容类型	SCI/SSCI论文
源URL	[http://ir.igsnrr.ac.cn/handle/311030/29578]
专题	地理科学与资源研究所_历年回溯文献
推荐引用方式 GB/T 7714	Li J.,Li J.,Yu Q.. Biophysical Controls on Light Response of Net CO2 Exchange in a Winter Wheat Field in the North China Plain. 2014.

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