Effects Of Grazing, Mixed Grazing And Mowing On Functional Traits And Nutrient Content Of Dominant Plants In Typical Grassland

This paper studies the effects of grazing,mixed grazing and mowing use on the Phenotypic traits,nutrient content,population characteristics,community density and above-ground biomass of the dominant plants of Leymus chinensis,Stipa krylovii and Cleistogenes squarrosa.Sampling was conducted at the peak of the plant community growth period in 2017 to determine the relevant indicators of dominant plants under grazing,mixed grazing and mowing in 5 years from 2012 to 2016.The research results are as follows:1.Both utilization methods make the L.chinensis phenotype dwarfed,N content reduced,grazing decline> mixed grazing and mowing;SW is sensitive,LW and the LN are inert traits;grazing enhances The correlation between Phenotypic traits and C,N,P content,L.chinensis under the stress,tend to allocate more total above-ground substances to leaves.2.The effects of two utilization methods on the phenotypic traits and stem P and C contents of S.krylovii are grazing> mixed grazing and mowing;grazing makes the N and P content of stems and phenotypic traits become a trade-off relationship,while mixed grazing and mowing To make the two into a synergistic relationship,S.krylovii purpurea adopts the adaptation strategy of increasing LN,NRB and maintaining a higher TLA and photosynthetic competitiveness to compensate for the dwarf-dense branching of the PH and WCC.3.The effect of grazing on the phenotypic traits of Cl.squarrosa > mixed grazing and mowing;Cl.squarrosa by adopting a nutrient acquisition strategy to increase leaf P content and a dwarf-dense branching adaptation strategy to increaseNVB,reduce PH and reduce WCC,to reduce disturbance stress,grazing weakens the relationship between its phenotypic traits and nutrient content.4.The response mechanisms of the biomass of the three plant populations are obviously different.The decrease of the individual biomass of L.chinensis is the main reason for the decline of the biomass of the population(non-density effect),that is,the biomass of the L.chinensis population is obviously affected by the individual traits.The individual traits of S.krylovii and Cl.squarrosa did not have a significant impact on the population biomass.What increased the population biomass was the increase in population density.5.The community biomass is mainly affected by the individual levels of L.chinensis and the population levels(density)of S.krylovii and Cl.squarrosa.And the three populations are obviously complementary.By comparison,the individual traits are the most unstable,the stability of the population is higher than the individual,and the stability of the community is higher.