Stipa grandis grassland productivity and utilization in Inner Mongolia: I. Dynamics of standing crop of pastures in grazing system

A study on standing crop of pastures in Stipa grandis grassland was carried out in Inner Mongolia during 1998～1999. It was shown that the standing crop was highly correlated with the growth rate of pastures and the grazing rate by animals. With a high growth rate of pastures, the quantity of standing crop was large and its seasonal changes were characterized with a single peak curve. The grazing intensity had a significant effect on the standing crop (P0.05). Under heavy grazing,the standing crop of Stipa grandis and Leymus chinensis could be seriously lowered. A too large amount of standing crop would hamper the re growth of Stipa pastures in spring, while a too small amount of standing crop would cause deterioration of the grassland.