The Remote Sensing Inversion And Validation Of Foliage Clumping Index Of Forest Vegetation In Daxing'an Mountains

The foliage clumping index quantifies the cluster degree of the leaf spatial distribution under random canopy.It is of comparable importance for ecological models establishment.The clumping index quantifies the level of foliage grouping within distinct canopy structures,such as tree crowns,shrubs and row crops,relative to a random distribution Foliage clumping has been shown to be significant for accurate estimation of absorbed photosynthetically active radiation photosynthesis and canopy conductance or the land surface energy balance.As the clumping index can vary considerably even within a land cover type,it is highly desirable to map the spatial distribution of this index using remote sensing data Previously,an improved angular index named normalized difference between hotspot and darkspot?NDHD?was proposed for retrieving the clumping index using multi-angle remote sensing data.MODIS BRDF model parameter products?MCD43A1 data?and land cover types?MCD12Q1 data?were used in this study to simulate the reflectivity of the hot spots and dark spots,and calculate the normalized difference between hotspot and darkspot?NDHD?based on the Ross-Li semi-empirical model.Least square method was then used to simulate the relationship between NDHD and the foliage clumping index and foliage clumping index products of 500-meter resolution in the August 2014 were retrieved.Measurements of the foliage clumping index in Daxing'an Mountains were conducted by using the TRAC?Tracing Radiation and Architecture of Canopies?sampling instrument for model validation and analysis.The real leaf area index were retrieved,And use the TRAC combined with LAI-2000?LAI-2000 observation LAI_e and TRAC observation?plug type?2-11???Referred to as combination method below?to calculate the real forest LAI in Daxing'an Mountains.The leaf area index obtained by combination method verifies the accuracy and the results are analyzed.Results show that:it is a feasible algorithm to retrieve clumping index from MCD43A1 product with the correlation of simulated data and the measured data of significance?R²=0.8879?;it is more sensitive of the MODIS near infrared wave band to foliage clumping index changes than red band;with the increase of the solar zenith angle,the clumping index retrieved by ROSS-Li model has a linear increase(R²_min=0.9699),which indicates that the foliage clumping index relates to the solar zenith angle.The forest canopy leaf area index is obtained by combination method and retrieved in Daxing'an Mountains has significant correlation.