Elymus Sibiricus L. Group Respond To Different Grazing Intensity In Grass Growing Season

To inquire into the Tibetan plateau and Elymus sibiricus L. for dominant grass suitable grazing intensity, the diagonal random quadrat sampling method is adopted, CK(cage), light grazing LG (feed rate 50%), moderate grazing MG (feeding rate 70%) and heavy grazing HG (feeding rate 90%) four grazing intensity were setted, a rotational grazing experiments were proceed in growing seasons, sampling investigation and indoor determination the Elymus sibiricus L. number of features, components, stem and leaf soluble sugar, sheep feed intake of the Elymus sibiricus L., the results showed that:1. Different grazing intensity on the Elymus sibiricus L. with characteristics of th e group of height, coverage, density, biomass and important value has the importa nt influence, with the increase of the grazing intensity decreases, the highest perfo rmance for CK, lowest for HG, exceeds the MG reached significant level (P<0.0 5); In the growing season, the Elymus sibiricus L. height and biomass of unimod al parabola changes, in July and August to spike, and significantly more than oth er months (P<0.05), the important value May (0.706) significantly larger than in J une(0.605), July (0.612), August (0.610) and in September(0.653) and October (0. 647) and the change was not significant (P<0.05), as the growth of the grazing i n, coverage did not change significantly, density decreased gradually, showed that July(749.306 branches/m2)>June(648.908 branches/m2)>May(632.000 branches/m2)> August(483.083 branches/m2)>September(353.089 branches/m2)>October(263.250 bra nches/m).2. Species components of different grazing intensity response change trend, stem leaf was not changed significant between grazing intensity, leaf number, reproductive branches number and leaf area index declined with the increase of grazing intensity, exceeds the LG reached significant level (P<0.05);In season grazing in different months, leaf number and leaf area index in July and August lager than in May, June, September and October (P<0.05), number of reproductive branch August(96.313 branches/m2)>September(63.511 branches/m2)>October(44.556 branches/m2), stem leaf ratio increases with growth in, September is the largest.3. Grazing intensity to the Elymus sibiricus L. stem leaf soluble sugar content was not significant, but the soluble sugar content in the component distribution of the performance of stem>leaf (P<0.05); cauline leaf soluble sugar content changes along with the growth of the grazing in trend is consistent, in May, June and July, stem and leaf soluble sugar content is low, to August significantly increased (P<005), and keep to September and October.4. Under different grazing intensity, the Elymus sibiricus L. standing stock, were feed intake and feed rate change trend were different, standing stock decreases significantly with the increase of grazing intensity (P<0.05), and show the CK(2099.624 kg/hm2)>LG(1462.485 kg/hm2)>MG(1033.713 kg/hm2)>HG(797.512 kg/hm2); Feed intake showed MG(0.556 kg/d*one sheep)>HG(0.672 kg/d-one sheep)>LG(0.633 kg/d#one sheep). Correlation analysis of feed rate and standing stock show significant negative correlation (P<0.05); The growing season to the Elymus sibiricus L. feed intake and feed rate along with the growth of the grazing in a parabolic variation, August to spike; after grazing sheep weight has increased, but the weight on the increase were decreases with grazing intensity increase, showed that LG(17.444 kg), MG(14.875 kg) and HG(14.549 kg), and increase of grazing intensity can improve livestock output perunit area in the short term, showed that HG(213.744 kg/hm2)>MG(168.396 kg/ hm2)>LG(142.724 kg/hm2), but bad for grassland plant growth and development, causes the degeneration of grassland, is not conducive to grassland sustainability.Appropriately grazing intensity utilizes to the Qinghai-tibet plateau with the Elymus sibiricus L. as dominant species, is to improve the ecological environment and improve the important measures for the sustainable development of animal husbandry. Both to ensure the sustainable development of grassland, alpine pastoral areas and improve the ecological and economic value.