Abstract: The formative regularity of aboveground biomass of six species of Agropyron and Elymus in transition region from dry to desesrt steppe at Yanchi county of Ningxia is studied from the view point of population. Results show that the height growth of tested herbages is varied with seasonal changes. The growth and development of Elymus junceus are earlier and faster than those of other 5 species. The aboveground biomass and available nutrients of E. junceus change with time and reach to the peak in growing season, their maximal values in milky stage being141.3 and 86.0g·m^-2 respectively. The optimal utilization period of forage grasses is pointed out and suggestions on grass prodution are put forward.

Key words: Agropyron L., Elymus L., Aboveground biomass, Available nutrient