Study On Niche, Interspecific Relationships And Functional Groups Under Enclosure In Meadow Steppe

In this study,meadow grassland as the research object,I collected the features of plant cover,height,density,frequency,aboveground biomass by sampling method.Based on the analysis of the vegetation niche,interspecific association and functional groups in the meadow steppe.The results were showed as follow:(1)Leymus chinensis had a wide range of utilization resources and strong adaptability to the environment in the study area.The ecological niche widths at 1,3,5 and 7 years of enclosure were 0.8037,0.8681,0.8143 and 0.8133 respectively.(2)The top three species in the first year of niche overlap values were Poa sphondylodes and Cleistogenes squarrosa,Poa sphondylodes and Leymus chinensis,Poa sphondylodes and Koeleria cristata.The niche overlap values were 0.8481,0.8272 and 0.7791 respectively.The top three species in the third year of niche overlap values were Poa sphondylodes and Cleistogenes squarrosa,Leymus chinensis and Caragana microphylla,Leymus chinensis and Poa sphondylodes.The niche overlap values were 0.7866,0.7848 and 0.7661 respectively.The top three species in the fifth year of niche overlap values were Poa sphondylodes and Stipa grandis,Leymus chinensis and Allium neriniflorum,Allium neriniflorum and Agropyron cristatum.The niche overlap values were 0.8563,0.8503 and 0.8409 respectively.The top three species in the seventh year of niche overlap values were Poa sphondylodes and Bupleurum chinense,Allium neriniflorum and Leymus chinensis,Poa sphondylodes and Cleistogenes squarrosa.The niche overlap values were 0.8575,0.7832 and 0.7769 respectively.(3)There were linear relationships of between niche breadth and niche overlap.The interspecific competition was increased with enclosure.Then,the interspecific generated niche differentiation and competition was decreased.The overlap of community towards stable state.(4)The number of species pairs with OI index of less than 0.6 in the first year was 93 pairs,accounting for 68.4% of the total species population.In the control plot,the number of species with OI index less than 0.6 was 76 pairs,accounting for 55.8% of the total species pairs.The number of species pairs with OI index of less than 0.6 in the third year was 105 pairs,accounting for 84.7% of the total species population.In the control plot,the number of species with OI index less than 0.6 was 96 pairs,accounting for 70.6% of the total species pairs.The number ofspecies pairs with OI index of less than 0.6 in the fifth year was 103 pairs,accounting for 54.2%of the total species population.In the control plot,the number of species with OI index less than0.6 was 88 pairs,accounting for 46.3% of the total species pairs.The number of species pairs with OI index of less than 0.6 in the seventh year was 95 pairs,accounting for 69.9% of the total species population.In the control plot,the number of species with OI index less than 0.6 was 85 pairs,accounting for 62.5% of the total species pairs.PC value and OI index change the same trend.However,except for the seventh year of enclosure,the maximum values of the OI index and PC value in the enclosure plots were higher than the control plots.The status of dominant species is obvious,the linkage of dominant species is high.The dominant species and accompanying species loosely linked.Species were independent,stable,not subject to fluctuations in community.(5)Enclosure had little effect on the quantitative characteristics of functional groups of shrubs,semi-shrubs and perennial parasites.But,the quantitative characteristics of perennial grasses have obvious effects.The first and third years of enclosure increased the coverage of perennial grass functional groups significantly.The first,third,and fifth years of enclosure increase the height of perennial grass significantly.The first and third years of enclosure increase the density of perennial grass significantly.The first,third,and fifth years of enclosure increase the biomass of perennial grass significantly.