Effects Of Coverage Change On Surface Hyperspectral Characteristics And Retrieval Accuracy Of Seriphidium Transiliense Desert Grassland

Desert grassland accounts for 20%of Chinaundefineds land area and has special ecological and production value.Remote sensing plays a great role in the realization of large-area dynamic monitoring.However,the coverage of this kind of grassland is generally low,and the ecological fragility is easy to degrade,which affects the inversion accuracy to a certain extent.It is of great significance to improve the monitoring accuracy of desert grassland for accurately grasping the current situation of grassland resources,optimizing its utilization and sustainable development.Therefore,aiming at the influence of soil background on plant canopy spectrum,this project takes the desert grassland,which is distributed in Xinjiang and on the degraded frontier,as the research object,and takes the ground image spectrometer as the platform.The effects of coverage change on the spectral characteristics of canopy and soil were studied by means of indoor control experiment and field measurement.The main findings are as follows:(1)The spectral values of the main species of Seriphidium transiliense in the desert grassland are affected by the change of coverage.When the coverage is increased,the reflectance of visible band decreases and the reflectivity of near infrared band increases.The first-order differential can express the"peak-valley" characteristics and the change amplitude of the original spectrum more clearly than other treatments,which enlarges the change characteristics of the coverage in the"red-edge" band.With the increase of coverage,the change range of spectral reflectance is basically stable.(2)The canopy spectral reflectance of Seriphidium transiliense desert grassland community increased with the increase of coverage,and the "red edge" band also had the strongest response to the change of coverage.Soil spectral reflectance also increases with the increase of coverage,and the response of soil spectral reflectance to coverage is more obvious than that of plant spectral reflectance.Savitzky-Golay smoothing filter can remove spectral noise more effectively than other processing,and enlarge the"peak-valley" characteristics of the original spectrum of the community.The change range of spectral reflectance of community canopy and soil was also stable.(3)When retrieving the coverage and biomass,the optimal combination band,vegetation index,model and accuracy are different due to the different plant species and coverage levels.There is no obvious difference between the accuracy of coverage inversion and that of coverage inversion,but the accuracy of single species inversion is always higher than that of community inversion.In single species biomass inversion,there is no significant difference between inversion accuracy of low coverage level and that of indiscriminate coverage level,but the inversion accuracy of low coverage level is basically higher than that of high coverage level and medium coverage level.In community biomass inversion,the inversion accuracy of indiscriminate coverage level is the worst,and the inversion accuracy of single species biomass is higher than that of community.Therefore,in order to effectively improve the inversion accuracy,the inversion of community biomass should be carried out by means of coverage inversion and species inversion.