The Influence Of Stocking Rate On Plant Community And Sheep In The Grazing System Of Stipa Breviflora Desert Steppe

The experiment was conducted in Stipa breviflora desert steppe in Siziwang Banner of Inner Mongolia from July to October in 2002. Six different stocking rates and non-grazing plot (CK) were set up with sheep in order to compare plant community and livestock responses to stocking rates in the experiment. The main results were as follows:(l) Coverage and density of plant community increased in lower stocking rate plots, and declined in higher stocking rate plots. The stubble heights of plants decreased in all stocking rate plots with time.(2) Net primary production of the plant species occurred equal-compensatory growth when the stocking rate was below 1.027sheep/hm2/year, but it decreased rapidly with the increase of stocking rate. (3) As the stocking rate increased the sheep liveweight gain increased at first, then declined successively. The liveweight gain per day was higher when the stocking rate was below 1.027sheep/hm2/year. (4) The diet of sheep was composed of a limited number of palatable plant species. The composition of diet had no difference among the stocking rates in the same season, but the number of plant species of diet declined with growth season. (5) Sheep has a higher preference to Convolvulus ammannii than any other plant species in August, but the preference ratio to Artemisia frigid increased at the end of the experiment, especially in higher stocking rates. (6) Compared to the higher stocking rate plots, the biting rate was lower in lower stocking rate plots, but the total foraging time was stable in all stocking rate plots. There were three times of sheep intake summits in stocking rate plots during the daytime. And the ruminating circle increased at the lower stocking rates.