Water,CO_2 and Energy Exchange at Vegetation-air Interface

[Objective] The aim was to analyze sensible and latent heat fluxes,CO2 fluxes and energy balance in wheat ecosystem in Luancheng in Hebei Province.[Method] Based on data of latent heat,sensible heat,CO2 fluxes,routine meteorological and biomass in Luancheng in 2008,sensible and latent heat fluxes,CO2 fluxes and energy balance were explored.[Result] The results showed that latent and sensible heat and CO2 fluxes were of obvious daily and seasonal changes;latent and sensible heat shaped an inverted U in daily change,and CO2 fluxes were of a U-shape;daily flux peak differed significantly.Furthermore,the change of latent heat,sensible heat and CO2 fluxes were closely related to environmental factors.Detailedly,the three were sensitive to light intensity and net radiation,and correlation coefficients were 0.92,0.66,0.65 and 0.90,0.69,0.74,respectively.Besides,the fluxes,sensitive to temperature,proved better in sunny day,especially for latent flux which is more sensitive to water in soils after precipitation.In addition,closure degree of energy balance in wheat fields was 0.91 and nonclosure,caused by measurement error and neglection of heat storage,was observed,too.Closure degree differed in months and time periods within a day.[Conclusion] The research concluded water and heat fluxes,CO2 fluxes,transport mechanisms and concerning factors,providing scientific references for revealing mechanism of evaporation and dissipation of canopy,relationship between photosynthesis and use efficiency of water and energy distribution mechanism.