Effects Of Root-cutting And Fertilization On Vegetation And Soil In Mowing Pasture Of Lymus Chinensis Meadow Steppe

Root-cutting and fertilizationis one of the direct and effective rehabilitationwayin degraded Lymus Chinensisgrassland.The grassland ecosystem nutrient input and output is imbalancebecause ofmowing for many years,existing nutrients cycle of soil and plant was destroyed,the grassland productivity has serious decline.Our research was based on Lymus Chinensis meadow steppe mowing pasture in Hulun Buir,researching the change law of vegetation and soil characteristics after root-cutting and fertilization by statistical methods?T test,Single-double factor analysis of variance,Regression analysis,Correlation analysis,Correspondence analysis,Principal component analysis?.Through the research on the functional group,community,soil physical,chemical and microbiological,providing theoretical guidance and reference for the degraded grassland.The main results:?1?In a period of time,Root-cutting increased the Lymus Chinensispopulation density?p<0.05?and the Lymus Chinensisyield,at the same time,It resulted in declineofSBD and it promoted the SH activity and reduced the content of SMC and SMN?p<0.05?.While soil nutrient content is not significant changeafter root-cutting.?2?The fertilization changed the population structure and increased the biomass of Lymus Chinensis.With the increase of fertilization level,the biomass of Lymus Chinensis increased gradually,and the Cleistogenes squarrosa proportion decreased gradually,and the Vicia amoena,Pulsatilla turczaninovii,Thalictrum squarrosumshowed a trend of first increase and then decrease as well as them existed a large proportion in H₁(Root-cutting+N3.5g.m^-2+P 1.7g.m^-2).?3?The fertilization significantly reduce the species richness of the community and functional group?p<0.05?.With the increase of fertilization level,Gramineousand Compositaefunctional important value increased significantly?p<0.05?,and Leguminosae,Ranunculaceae,Othersfunctionalgroupimportant valuedecreased gradually?p<0.05?.?4?The effect of fertilizationto CAB is greater than the CUB,The CAB increased significantly?p<0.05?,while the CUB no significant change?p>0.05?.When abundant precipitation,there was significant function relationshipbetweenfertilization andthe yield.With the increase of fertilization level,the yield increased gradually and existed a maximum in H₃(Root-cutting+N 10.5g.m^-2+P 5.1g.m^-2).?5?The community nutrient content changedsignificantlywith the fertilization level?p<0.05?.When abundant precipitation,CTPincreased with the increase of fertilization level and community C/P ratio is decreasedgradually with the increase of fertilization level.When deficient precipitation,the CTC and CTN decreased with the increase of fertilization level,while community C/N ratio increased gradually with the increase of fertilization level.?6?The fertilization significantly increased the nitrogen and phosphorus content of soil nutrient,while the kaliumcontent no significant change?p>0.05?.10²0cm STP and0¹0cm,10²0cm,20³0cm SANincreased significantly?p<0.05?.0¹0cm STN showed significantly rising trendwith the increase of fertilization level?p<0.05?.?7?The fertilizationsignificantly increased SU activity and SMC content?p<0.05?,While the SS and SH no significant change?p>0.05?.The SMNshowed a trend of first decreasedand then increasedwith the increase of fertilization level?p<0.05?.?8?When abundant precipitation,there wassignificantly positive correlation between STN and SAN?p<0.05?.When deficient precipitation,there was significantly positive correlation between CTC and CTN?p<0.01?,and there was significantly negative correlation between SAN and SU?p<0.05?.Whether abundant precipitation or deficient precipitation,H₁(Root-cutting+N 3.5g.m^-2+P 1.7g.m^-2)isthe most optimal improvement method inlocalgrassland.