A Study On Sheep Diet Of Different Stocking Rates On Stipa Breviflora Desert Steppe

The relationship between grassland and animals is research emphasis of grazing ecology in ecosystem. The experiments was conducted on stipa breviflora desert steppe in Siziwang banner of Inner Mongolia from 2007 to 2008. Different stocking rate were setting up, that is light grazing (LG), moderate grazing (MG), heavy grazing (HG) and control (CK), and 4 treatments were offered with random order while each repeated 3 times. Through sheep diet composition, differences of feeding habits and diet function group at different stocking rates on desert steppe, the relationship among feed law, food intake state, feeding habits and grassland community were discussed. The daily diet composition and its seasonal changes of grazing sheep and the affects of different stocking rates on sheep diet and grassland condition was analyzed, The diet rules of grazing sheep at different stocking rates, and food replace regular under stress of food resources were revealed.The results were showed as follows:(1) The trend of similarity index of the composition of diet and vegetation composition was almost opposite during 2007 and 2008, Similarity indices of MG plot was lower compared with LG, HG in July.(2) Artemisia frigida, Stipa breviflora, and Convolvulus ammannii were daily forage of seasonal grazing sheep at LG, MG, HG plot in July from October during 2007 and 2008. Cleistogenes songorica, Stipa breviflora, Artemisia frigida, Convolvulus ammannii, Potentilla acaulis, and Neopallasia pectinata took a larger proportion of total feed intake. It was more than 94% in LG plot, more than 97% in MG plot, and more than 98% in HG plot during 2007 and 2008.The plant kind numbers of sheep intake in LG district was more than MG and HG. .(3) The difference of foraging proportion among different plant species in the same month was abvious(P<0.05). The difference of bush foraging was significant among different treatments in every month(P<0.05). The differences of foraging on grasses, annial plant, and biennial plant were abvious in 2008 (P <0.05). The differences of foraging on functional group of various feeding habit were distinct at the same treatment in different month (P <0.05).(4)The preference level of different forages changed relatively. During 2007 and 2008, acceptabilty index of Cleistogenes songorica was higher in HG plot in July and August. The species was favorite in July, preferable in August, and preferable in September in HG plot Stipa breviflora and Neopallasia pectinata were favorite in HG plot in August.(5) The functional groups of various feeding habit complemented each other at different stocking rates among months in the same year, preferable food index of grasses was lower in 2007, In LG plot, it expressed favorite in July and Sptember, In MG, HG plot , it was available or little. Preferable food index of shrubs presents favorite or preferable among July, August, and September in LG plot. While it presents favorite in July and August in MG plot. It noly presents favorite in August in LG plot. Preferable food index of perennial weeds presents favorite or preferable at various treatments. Preferable food index of annial and biennial plants present favorite or preferable in September in HG plot.(6) It had a great closely correlation between plant diversity and forage diversity among LG plot, MG plot and HG plot in 2007 (P<0.05). There was significant difference between plant diversity and food diversity in LG plot and MG plot (P<0.05), but no significant difference in MG plot in 2008. Plant diversity and food diversity were higher under the moderate grazing stress, the relative index of plant diversity and food diversity were decreased under light and heavy grazing rate , it was more abvious in HG plot. Foraging was single all the more.