Response Of Stipa Breviflora Grassland To Banning And Defered Grazing And Livestock Penfeeding System

Effects of banning and defered grazing on plant population, community structure, soil physical and chemistry characteristics and plant nutrition composition of Stipa breviflora desert steppe were investigated during 2006-2008 years.From April 5th 2007 to June 5th of 2007, 24 2-year-old wethers were randomly divided into 4 groups. the sheep were separately fed with diets of different nutritious levels. Feed comsumption, nutrient absorption and digestion rate were measured by collecting the leff-over forage and analysing dune composition,to determine the appropriate daily diet supply ration.The diurnal changs of photosynthesis and photosynthetic response curves of Stipa breviflora, Allium polyrhizum and Cleistogenes songorica under different grazing levels were measured and compared by using LI-6400 photosynthesis system during grass growing season in August 2008.Responses of plant populations, communities, and soil to banning grazing and defered grazing were studied. Forage supply model based on livestock penfeeding nutritional balance under different defered grazing period were proposed by measuring plant community characteristic, grass nutrition component and daily diet nutrient component. The main results were as follows:1 The height of Stipa breviflora increased with extend of defered grazing period, but long-term banning grazing had negative effects on the growth of Stipa breviflora. Banning and defered grazing were beneficial to increase the height and density of annual plants and total density. 50-60d of defered grazing was more beneficial for improving the coverage of community. Banning and defered grazing were beneficial to accumulate the carbohydrate components of Stipa breviflora, Cleistogenes songorica and Allium polyrhizum, and were more beneficial to spring re-greening of the following years.2 Banning and defered grazing increased the photosynthetic rates, transpiration rates, and internal CO2 concentration of the major plant species on desert steppe .3 Plant aboveground standing crops in Banning and defered grazing were higher than that in continuous grazing, but was not proportional to the duration of defered grazing, 50 day of defered grazing was considered a rational regine. 5 Banning and defered grazing reduced soil bulk density, and increased soil porosity and soil water content, which was not directly proportional to the defered grazing duration.6 Results of the experiment showed that daily diet supply of 0.5kg straw+0.5kg silage+0.05Kg corn+10g NaCl were suitable to the local condition.