Study On Quantitative Characteristics And Stability Of Mowing Grassland Community Of Grazing Exclusion

The meadow grassland in the eastern part of Inner Mongolia was taken as the research object.The quantitative characteristic indexes of mowing communities from enclosed and mowed,grazing and mowing,mowing pastures and forbidding pastures include aboveground biomass,litter,functional group biomass,density,coverage and height,diversity,stability and group.The response process and mechanism of the community to cutting were analyzed at four levels in the dynamic process of falling.The main conclusions are as follows:The main results were as follows:(1)grazing ban for 8 years had a positive effect on the aboveground biomass of the community,and cutting decreased the recovery ability of the aboveground biomass of the community,EN>EC.The difference of aboveground biomass between enclosure and cutting treatment after 3 years of grazing ban.The ratio of aboveground biomass was 51.67%in flat water year and 24.59%in high water year.the aboveground biomass of perennial grasses and shrubs and semi-shrubs provided a positive contribution to the difference.the aboveground biomass of the five functional groups was higher than that of cutting in dry year enclosure treatment.In abundant years,the proportion of composited and perennial miscellaneous species was-35.70%and-20.06%,respectively.enclosure was not conducive to the growth of aboveground biomass of composited and miscellaneous grasses.The annual enclosure and cutting treatment had a significant effect on the coverage and height,and the enclosure was beneficial to the increase of community coverage and height,but had no significant effect on the density.The effects of grazing prohibition and grazing on aboveground biomass and height were significant.the aboveground biomass and height of FM treatment were higher than that of GG;density,which were not sensitive to cutting and grazing treatment,and the difference was not significant in 5 years.Grazing ban could not increase community density;the difference of coverage in 2012 and 2014 was significant,but not in 2015 and 2017,and the effect of mowing and grazing on coverage was regulated by precipitation.Under mowing treatment,the effects of traditional mowing grassland and forbidden pasture on aboveground biomass and density were significant.the coverage and height of NM>EM;were significantly different from 2013 to 2015,but not from 2016 to 2017.(2)after grazing ban,EN and EC treatments had no significant effect on species and number,Steppe grandis,Leymus chinensis and Cryptosporidium Chinese were the dominant species,and the number of Composite plants in high water years was the largest.Grazing and mowing treatments had significant effects on species and number.under the management of FM>GG;mowing,the dominant species succession of plant community in traditional mowing grassland was POA pretenses,and the mowing grassland was Steppe arundinacea,Leymus chinensis and Cryp to sporidium striatum.However,there was no significant difference in the number of species,and the frequency distribution of the six treatments did not meet the requirements of the standard frequency law,and the stability and uniformity of the community were poor.The frequency of EN and EC increased with the increase of years,B+C+D showed a downward trend,E showed a fluctuating trend.The frequency of FM treatment was significantly different from that of GG treatment,and the change trend of GG treatament fluctuated greatly.NM treatment grade A fluctuated,B+C+D showed an upward trend,E grade showed a downward trend,EM treatment A showed an upward trend.B+C+D showed a downward trend.The diversity indexes of Simpson's,Shannon-Weinerhe and Pielou of enclosed communities were lower than those of mowing,while the diversity indexes of P w,Cody and ? t were opposite.the species replacement rate of enclosed communities was higher than that of mowing.The diversity index of a and ? of FM treatment in 2014 and 2016>GG,was beneficial to cutting in the other three years of FM<GG,while it was beneficial to grazing in the year of low water.(3)the five quantitative characteristic indexes of aboveground biomass,species number,coverage,height and density increased at first and then decreased between 2010 and 2017,which was consistent with the changing trend of precipitation,and precipitation was positively correlated with aboveground biomass and species number.(4)the community stability of EN and EC treatment increased with the increase of years,and the stability index was 27<73 and 26 ? 74 in 2017,which was unstable compared with 20 ? 80 standard.FM and GG treatments had significant effects on stability,the plot stability index fluctuated at 22?78 ? 27 ? 73,and the community stability was better,but FM>GG;NM and EM treatments had no significant effect on stability.