Calculation of clumping index of mixed pixel and scale analysis

Clumping index is an important vegetation structure parameter to describe the foliage clumping in canopy quantitatively. It is defined as the ratio of the effective leaf area index to the true leaf area index. In previous studies, it is generally considerate that cluster of canopy and below canopy scale in pure pixel. However, the in-pixel spatial heterogeneity need be taken into account estimating clumping index in mixed pixel, which is different from clumping index of pure pixel. A new method to calculate clumping index of mixed pixel based on fine spatial resolution image is proposed in this paper. The sensitivity analysis has been processed and its results show that the pixel spatial heterogeneity and view zenith angles cannot be ignored for calculating the mixed-pixel clumping index. The method is capable of correcting the scale difference caused by the heterogeneity of the vegetation cover inside the mixed pixel the view zenith angle. The formula presented can estimate clumping index of the mixed pixel more accurately, which is significant for LAI inversion of coarse spatial resolution and the precision accuracy application of carbon cycle model.