Remote Sensing Inversion And Spatio-Temporal Dynamic Analysis Of Litter Coverage

Residue layer is not only the most important level of vegetation community vertical structure,but also has certain functions of Soil and water.And it plays an important role in preventing soil erosion.As the storage of organic carbon and nutrients in ecosystem,it sustains the material circulation and energy flow of ecosystem.Residue coverage was inverted through remote sensing method to obtain the information of the litter cover on the regional scale rapidly.That was of great significance for analyzing Spatio-Temporal diversification features of residue layer and realizing the dynamic monitoring.Furthmore,it was beneficial for Evaluation of soil and water conservation functions of the litter layer and research of carbon source/carbon sink balance.The study area was in the center of Shaanxi Loess Plateau region,and The data sources were measured spectrum,residue cover and Landsat image.Residue and soil line were extracted through analyzing characteristics of soil and residue spectrum spatial.The CRIM,DFI,and MSACRI were worked out.Correlation between decaying vegetation index and measured litter cover was compared so that the optimal decay vegetation index could be determined which was used for establishing a regression layer inversion model.Based on analyzing of relationship between grading information of litter cover and landuse of study area,transfer matrix method and difference method were adopted to analyze Spatio-Temporal variable features of residue cover of study area in first period(2015-2016),second period(2016-2017)and the whole period(2015-2017).The results included:Based on the analysis of soil and residue spectrum spatial characteristics,it was found that OLI3-OLI4 spectrum space was most beneficial for the extraction of soil lines and litter lines.CRIM could be used to describe residue cover directly with physical process.DFI was more applicability and better than CRIM and MSACRI.The DFI was used as the optimal decay index for inversion of the cover layer in this paper.According to the analysis of the grading information of the litter cover and the landuse data of the study area,the spatial distribution of the cover of different grades had a certain relationship with the landuse type.The study area was divided by the west of the boundary was mainly grassland,and the east was mainly forest land.The cultivated land was distributed throughout the study area.Grassland's area was the largest in the study area,and the cover of the litter layer was mainly poor level;followed by forest land with good and excellent level.The area of cultivated land is the smallest.The cover is the main inferior level and the litter composition is single and easily decomposed,so the soil and water conservation effect is the worst.The unchanged area of litter remained a certain level in three periods in study area.The positive change was always higher than the negative,so the litter cover was developed better.The area where the level of the litter cover was unchanged was maintained about 40%,and the amount of forward transfer always accounted for a large proportion,which reflected the transition from low coverage to high.The change of the spatial position of the litter cover of each level was more active.In short,the litter cover had been improved year by year,and the soil and water conservation of he litter cover had been continuously strengthened.The ecological construction had achieved certain results.