Abstract
Obtaining accurate information on the fractional cover of non-photosynthetic vegetation (NPV) (fNPV) on grasslands is essential for monitoring soil erosion risk, assessing grassland productivity and managing grassland ecosystems. However, few studies have monitored fNPV in the Xilingol grassland region (XGR) and its spatiotemporal variations based on Moderate Resolution Imaging Spectroradiometer (MODIS) images. In this study, we determined the upper dead fuel index (DFI) threshold for NPV in the XGR. Then, a remote-sensing inversion model for fNPV was established based on the ground-measured fNPV and the DFI derived from MODIS images. Based on the inversion model, we obtained the spatial distribution and spatiotemporal variations in fNPV from 2000 to 2019. The results indicated that the DFI can reflect the NPV in the XGR with an upper threshold of 27.2. The DFI-fNPV linear regression model showed a good performance, with a coefficient of determination (R2) of 0.60 and a root mean square error of leave-one-out cross-validation (RMSECV) of 0.1574. Furthermore, the spatial distribution of fNPV exhibited significant heterogeneity, and fNPV decreased from the northeastern XGR to the southwestern XGR. The overall trend of the interannual fNPV in the XGR increased in a fluctuating manner during 2000–2019. The fNPV increased in 66.92% of the XGR and decreased in a relatively small proportion (18.21%) of the XGR.
Acknowledgements
We are grateful for support from by the National Natural Science Foundation of China (Grant No. 41701005 and 41601598).
Disclosure statement
No potential conflict of interest was reported by the authors.