Light use efficiency of vegetation:A review

Light use efficiency(LUE)represents the efficiency of vegetation in converting solar energy to biomass through interception/absorption and photosynthesis.It is an important index in quantifying the solar energy utility of vegetation in photosynthesis,and the theoretical basis in large scale monitoring vegetation productivity based on remote sensing.The general method of determining LUE is to estimate the plant biomass by harvest on plot scale,and then,a value of LUE is given as a ratio of biomass and observed solar energy for a whole year or a growth season.Eddy covariance technique is regarded as a unique method which can directly observe the flux of CO2,H2O and heat between atmosphere and vegetation,making it possible to estimate LUE on large scale from canopy to landscape.LUE has specific spatial heterogeneity and temporal variability,because of the differences of vegetation and climate.On global scale,the inversion simulation by coupling atmospheric CO2 observation,remote sensing and atmospheric radiation transfers model can confirm the geographic variance of LUE of net primary productivity.There are many factors affecting the spatio-temporal pattern of LUE,mainly including plant physiological(such as leaf form and ribulose diphosphatecarboxylase content)and environmental factors.In order to give a good answer on the spatio-temporal pattern and its fluctuation of LUE,the crossing-scale modeling based on flux observation and model analysis may be an important research field in the future.