Abstract
Surface energy fluxes were measured using Bowen-Ratio Energy Balance technique (BREB) and eddy correlation system at Luancheng of Hebei Province, on the North China Plain from 1999 to 2001. Average diurnal variation of surface energy fluxes and CO2 flux for maize showed the inverse “U” type. The average peak fluxes did not appear at noon, but after noon. The average peak CO2 flux was about 1.65 mg m-2 s-1. Crop water use efficiency (WUE) increased quickly in the morning, stabilized after 10:00 and decreased quickly after 15:00 with no evident peak value. The ratio of latent heat flux (λE) to net solar radiation (Rn) was always higher than 70% during winter wheat and maize seasons. The seasonal average ratio of sensible heat flux (H) divided byR n stayed at about 15% above the field surface; the seasonal average ratio of conductive heat flux (G) divided by Rn varied between 5% and 13%, and the averageG/R> n from the wheat canopy was evidently higher than that from the maize canopy. The evaporative fraction (EF) is correlated to the Bowen ratio in a reverse function.EF for winter wheat increased quickly during that revival stage, after the stage, it gradually stabilized to 1.0, and fluctuated around 1.0. EF for maize also fluctuated around 1.0 before the later grain filling stage, and decreased after that stage.
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References
L’vovich M I, White G I, 1990. Use and transformation of terrestrial water systems. In: W.C.C.Turner BLet al. (eds.), The Earth as Transformed by Human Action. UK: Cambridge University Press, 235–252.
Ohta T, Hiyama T, Tanaka Het al, 2001. Seasonal variation in the energy and water exchanges above and below a larch forest in eastern Siberia.Hydrological Processes, 15: 1459–1476.
Rana G, Katerji N, 2000. Measurement and estimation of actual evapotranspiration in the field under Mediterranean climate: a review.European Journal of Agronomy, 13: 125–153.
Sellers P J, Bounoua G J, Collate D Aet al., 1996. Comparison of radiative and physiological effects on doubled atmospheric CO2 on climate.Science, 271: 1402–1406.
Steduto P, Hsiao T, 1998a. Maize canopies under two soil water regimes I: diurnal patterns of energy balance, carbon dioxide flux, and canopy conductance.Agric. For. Meteorol, 89: 169–184.
Steduto P, Hsiao T, 1998b. Maize canopies under two soil water regimes II: seasonal trends of evapotranspiration, carbon dioxide assimilation and canopy conductance, and as related to leaf area index.Agric. For. Meteorol., 89: 185–200.
Todd R W, Evert S R, Howell T A, 2000. The Bowen ratio-energy balance method for estimating latent heat flux of irrigated alfalfa evaluated in a semi-arid, advective environment.Agric. For. Meteorol., 103: 335–348.
Wang H, Zhang L, Liu C, 2001. Improving water use efficiency of irrigated crops in the North China Plain: measurements and modeling.Agricultural Water Management, 48: 151–167.
Woodward F I, Smith T M, 1994. Global photosynthesis and stomatal conductance: modeling the controls by soil and climate.Botanical Resources, 20: 1–41.
Yu H N, Liu X, 1992. A study on CO2 flux density and water use efficiency of crop community at field. In: Study on the Correlation between Crop and Water. Beijing: China Science and Technology Press, 1–7.
Zhang Yongqiang, Shen Yanjun, Liu Changminget al., 2002. Measurement and analysis of water, heat and CO2 flux from a farmland in the North China Plain.Acta Geographica Sinica, 57(3): 333–342. (in Chinese)
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Yongqiang, Z., Yanjun, S., Qiang, Y. et al. Variation of fluxes of water vapor, sensible heat and carbon dioxide above winter wheat and maize canopies. J. Geogr. Sci. 12, 295–300 (2002). https://doi.org/10.1007/BF02837548
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DOI: https://doi.org/10.1007/BF02837548