Abstract: This paper studied the effect of grazing on biomass formation dynamics of Leymus chinensis at population level in the northeastern China grassland. The results show that the assimilation system standing biomass (ASSB), unassimilation system standing biomass (UASSB),litter accumulation, living rhizome biomass (LRB) and dead rhizome biomass (DRB) were decreased significantly with increasing grazing intensity. At heavily grazing stage, they were respectively 48.6,49.4,41.3 and 51.4% of those at lightly grazing stage. The same seasonal variation tendency was found between ASSB and UASSR, and between LRB and DRB.

Key words: Grazing, Leymus chinensis population, Biomass formation dynamics, similarity coefficient, isolation frequency, diversity index, Pteroceltis tatarinowii