The Impact On The Vegetation Of Stipa Breviflora Desert Steppe Under Different Grazing Systems And Rotational Grazing Time

The paper studied on the vegetation of Stipa breviflora desert steppe during2010-2012, which in order to reveal the variations of the main plant population andcommunity in Stipa breviflora desert steppe under different grazing systems and grazingtime using contrastive analysis, association study and geostatistical analysis. The mainresults were as follows:1The coverage and density of Stipa breviflora were larger in early grazing and thecoverage and density of Cleistogenes songorica were larger in medium grazing. Indifferent grazing systems, the height of Stipa breviflora, Allium polyrhizum andCleistogenes songoriea in rotational grazing were higher than those in continuous grazing.The coverage and density of Stipa breviflora in continuous grazing were higher than thosein rotational grazing, while the coverage and density of Cleistogenes songorica and thecoverage of Allium polyrhizum in rotational grazing were higher than those in continuousgrazing. The important values of Stipa breviflora were low in medium grazing, while incontrast the important values of Cleistogenes songorica were low in late grazing and thehighest in medium grazing. The important values of Stipa breviflora were higher incontinuous grazing than that in rotational grazing, and rotational grazing had betterincreased the important values of Cleistogenes songorica than continuous grazing.2In different grazing systems, aboveground biomass of Stipa breviflora incontinuous grazing was greater than that in rotational grazing, while on the contrary forAllium polyrhizum and Cleistogenes songoriea. The changes of aboveground biomass incontinuous grazing were affected obviously by the main plant population, and percentagein total aboveground biomass was more than70%.3The rotational grazing brought the main plant population base greater, while thecontinuous grazing brought the crown breadth and stem breadth greater. Meanwhile,continuous grazing had more plant lamina than rotational grazing and the same results forthe amount of root system of Stipa breviflora and Cleistogenes songoriea.4The relationships among plant population were complicated in early grazing RG2,medium grazing RG5and late grazing RG7and RG8. Continuous grading resulted in theweak association of plant population. In different small areas, there existed differenceamong the relative preference of species, and meanwhile, their interspecific association had also greatly changed.5The main plant population space distributed in continuous grazing was muchaffected by structural influence. The main plant population space distribution of rotationalgrazing was complicated. The leading function of species number, total coverage and totaldensity in rotational grazing was stronger than that in continuous grazing.6For different grazing time, medium grazing was relatively more reasonable, whilefor different grazing systems, rotational grazing was better than continuous grazing.