Modelling aboveground biomass using MODIS FPAR/LAI data in alpine grasslands of the Northern Tibetan Plateau

Aboveground biomass (AGB) is a vital variable in global carbon cycling and plays important roles in ecosystem structure and function in grasslands. Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 6 leaf area index (LAI) and fractional photo-synthetically active radiation absorbed by vegetation (FPAR) data were used to model AGB in alpine grasslands in the Northern Tibetan Plateau. MYD15A2H (derived from the Aqua MODIS with a temporal resolution of eight days) FPAR/LAI with lower RMSE values (< 18 gm(-2)) may have higher estimated accuracies than MOD15A2H (derived from the Terra MODIS with a temporal resolution of eight days), MCD15A2H (derived fromthe combination of Terra MODIS and Aqua MODIS with a temporal resolution of eight days) and MCD15A3H (derived from the combination of Terra MODIS and Aqua MODIS with a temporal resolution of four days) FPAR/LAI with higher RMSE values (> 20 g m(-2)). The RMSE values (11.42-13.27 g m(-2)) in the open grazed areas were lower than those (17.46-17.56 g m(-2)) in fenced areas for MYD15A2H. Therefore, the estimated accuracies of AGB may vary among the four MODIS FPAR/LAI products and land use types in alpine grasslands of the Northern Tibetan Plateau.