Estimation Methods Of Leaf Area Index Of Moso Bamboo Forest

Leaf area index（LAI）is the main variable to model many processes,such as canopy photosynthesis and evapotranspiration.LAI of Moso bamboo canopies has been estimated and used for determining the size of the plant-atmosphere interface and thus modeling the exchange of energy and mass between the canopy and the atmosphere.However,as far as out known,all ground-based estimations of LAI of Moso bamboo canopies were conducted based on the indirect remote sensing methods.The estimated LAI has not been validated before it was used as input parameter of terrestrial ecosystem models and for validating LAI retrieved from satellite-based observations.In addition,the small values of LAI of Moso bamboo canopies estimated by previous studies conflict with the common sense of such the extremely dense canopies.In order to explore the reality of LAI of Moso bamboo canopies,it is the first attempt to estimate its LAI using the allometric model based on the destructive measurement.The results indicate that（1）the LAI of Moso bamboo canopies ranges from 6.7m²·m^-2 to 30.6m²·m^-2,which is far beyond the ranges from2.2m²·m^-2to 6.5m²·m^-2 estimated by previous studies;（2）the linear relationship between LAI and crown density of Moso bamboo canopies is strong（R²=0.947,RMSE=1.343）;（3）LAI of Moso bamboo canopies are largely underestimated using the ground-based digital hemispherical photography（DHP）because of the overestimation of clumping index;and（4）the exponential relationship between LAI of Moso bamboo canopies and its effective leaf area（L_e）estimated by DHP is strong（R²=0.734,RMSE=3.011）.According to the results,the three methods are recommended for LAI estimations of Moso bamboo canopies using the allometric relationship,the empirical relationship with crown density,and the empirical relationship with L_e,respectively,and,therefore,will potentially serve as a crucial reference for estimating carbon balances and other ecological studies of Moso bamboo forests.