Effect Of Different Grazing Intensities On Vegetation And Soil Physical And Chemical Character

The effects of the different grazing intensity on grassland vegetation and soil physical and chemical Properties were researched on the Yuershan farm of Hebei province from may to September. The aim of experiment was to find out a appropriate grazing intensity of this type range. It was divided into light (6 sheep/hm2), middle(10 sheep/hm2), heavy grazing(13 sheep/hm2) and contrast treatments(0 sheep/hm2).The results showed that: with the increasing intensity of grazing pressure from light,middle to heavy ,plant height ,dengsity ,standing crop of community decreases significantly; coverage of grassland decreased, but not significantly ;In general, the diversity index of middle grazing and contrast treatments are superior to heavy grazing group, regardless of livestock species richness, evenness, or the number of species,having the same trend with important value index.The content of avaliable crude protein was the highest in June. with the increasing intensity of grazing pressure from light,middle to heavy , the crude protein content declined, fat and fiber content increased. calcium content of heavy grazing have the same trend with control groups basically on early grazing,but it was higher than other groups significantly (P﹤0.05)at latter.the change trend of phosphorus content increased at first then decreased.The Soil moisture content of 0-10cm surface decreased at first then increased soil total N and 0~20cm layer available K have an obvious trend of increasing along grazing gradients(from LK to HG).Total P decreased. The change of organic matter was not significantly.Appropriate grazing can stimulate the growth of pasture and improve the primary productivity of grassland .So it is very important to determine the appropriate intensity of grazing in the production of practice.