A NOVEL SPECTRAL LINEAR TRANSFORMATION TO ESTIMATE NON-PHOTOSYNTHETIC VEGETATION COVERAGE IN NORTH ASIAN STEPPE

Abstract. Non-Photosynthetic Vegetation (NPV) coverage is an important parameter for wildfire danger rating, prevention of soil erosion and carbon sequestration estimations. A group of spectral indices have been developed to map NPV distribution based on hyperspectral data or particular application scenarios. However, the NPV coverage estimated by those indices are not stable because they are sensitive to soil moisture or snow cover. This paper aims to develop a spectral linear transformation named as Non-photosynthetic Vegetation Index (NPVI) based on Moderate Resolution Imaging Spectroradiometer (MODIS) data to estimate non-photosynthetic vegetation (NPV) coverage in north Asian steppe. The validation result of field spectral experiment and field survey shows the NPVI has good potential to estimate NPV coverage and are robust to soil moisture and snowmelt. Furthermore, the seasonal variation of NPVI offers the possibility to monitor the wildfire risk and grazing intensity.