Based on the data accumulated during a period of more than 30 years at 2352 meteorological stationsover China and data from other sources,the existing Comprehensive and SequentiaI Classification Systemwas improved in this study by revising the original indices of thermal and humidity grades employed in thefirst-level classification of grasslands,that is the identification of grassland classes.A new index chart wasalso designed and computerized in which the zonal natural grasslands,azonal natural grasslands(...