Research On Inversion Of Litter Layer Coverage Based On The Dimidiate Pixel Model

Vegetation is the core of the terrestrial ecosystem,and the litter layer is not only an important level in vegetation community vertical structure,but also a key storage of organic carbon and nutrients in ecosystem.It is of great significance to correctly understand the important role of the litter in the ecosystem and to promote the study of carbon/carbon balance in the region by using the coverage information of the litter in the region with remote sensing images.Based on the Landsat-8 OLI image and the measured spectrum and coverage data of samples,this paper studied the hilly and gully areas of the Loess Plateau in northern Shaanxi.Firstly,the feasibility of distinguishing the litter layer and the soil based on the DFI index was explored by the analysis of the litter and soil spectral characteristics,and the applicability of the vegetation index with other decay vegetation indices in the Dimidiate Pixel Model was studied.Then,we choose the optimal decay vegetation index,and use the end feature eigenvalue and the Dimidiate Pixel Model to invert the coverage of the study area and use the sample data to verify the accuracy.Finally,the spatial distribution characteristics of the litter cover are analyzed by land use data and DEM data.The conclusions as follows:(1)The DFI index based on Landsat-8 OLI image can effectively distinguish between soil and litter layers.In the dry state,the DFI index is more discriminative than the NDSVI,NDTI and MSACRI indices.There are good linear correlations between DFI and NDTI based on field measurements and different types of litter coverage.(2)Based on the DFI index and the spectral feature space,the coverage of the study area using the Dimidiate Pixel Model inversion is related to the litter cover of the sample.The average coverage of the litter cover in the study area is 40.64%,which is dominated by low coverage and lower coverage.The coverage of the Forest land,grassland and arable land is better,but the unused land is worse.(3)The litter layer with different levels of coverage in the 900-1300m distribution proportion is the largest.The litter layers with different coverage degrees are affected by the slope,and the coverage ratio of each layer is increased with the increase of the slope.The maximum proportion of the litter cover is in the range of 15°-25°.In the range of 0°-15°,the distribution of the low-level litter layer is the largest,and at the slope of>25°,the distribution of the high-coverage layer is the largest.The higher-coverage and the high-coverage of the litter are more affected by the aspect,and the lumps of the middle cover are evenly distributed in each slope.The distribution proportion of the litter layer of the lower-coverage and the low-coverage in sunny and semi-sunny slopes is larger,while the distribution proportion of the litter layer of the high-coverage and higher-coverage in the shady and semi-shady slope is larger.