Study On The Eco-Stoichiometric Characteristics And Soil Enzyme Activities Of Saline-Alkali Grassland In The Farming-Pastoral Ecotone Of North Shanxi Province

Grassland soil salinization will not only cause soil compaction,but also seriously affect the absorption of nutrients by plants.The area of saline-alkali land in northern Shanxi accounts for 60.2%of the total area of saline-alkali land in the province.The development of grassland and animal husbandry in this area is seriously affected by soil salinization.Soil eco-stoichiometric characteristics and enzyme activity can characterize soil nutrient supply capacity and affect plant eco-stoichiometric characteristics.Taking the saline-alkali grassland in the agricultural-pastoral ecotone of northern Shanxi as the research object,the changes of eco-stoichiometric characteristics of plants and soil under three saline-alkali gradients were analyzed.Changes in sucrase and alkaline phosphatase enzyme activities.The research results are as follows:(1)With the increase of salinity,vegetation coverage,density,height,aboveground biomass,underground biomass,total biomass,root organic carbon,total nitrogen,C/P,N/P and soil Nitrate nitrogen showed a downward trend.As the degree of salinity increases,the Margalef index of the plant and the soil water content,bulk density,pH,total soluble salt,ammonium nitrogen,C/P,catalase activity show an upward trend.(2)The total phosphorus,C/N,urease,and sucrase enzyme activities of the soil in the mild saline-alkali land were significantly higher than those in the moderate and severe saline-alkali land,and the total phosphorus in the vegetation on the moderate saline-alkaline land was significantly higher than that in the mild saline-alkali land,moderate-and severe saline-alkali land.The total phosphorus and soil N/P of the aboveground vegetation were significantly higher than that of the mild saline land,the N/P of the vegetation of the severe saline land was significantly higher than that of the moderate saline land,and the ammonium nitrogen of the soil of the severe saline land was significantly higher than that of the mild and moderate saline land.(3)Vegetation Shannon-Wiener index,Pielou evenness index,organic carbon,total nitrogen,C/N,C/P,underground root C/N,soil organic carbon,total nitrogen and alkaline phosphatase enzyme activity,There is no significant change under the three salt-base gradients of mild,moderate and severe.(4)The total nitrogen and N/P of the underground root system of mild saline and moderate saline land in this study area are significantly correlated with soil nitrate nitrogen;the density of vegetation in the severe saline land and soil pH,organic carbon,nitrogen to phosphorus ratio,urease There is a significant correlation with invertase activity,and there is a significant correlation between underground biomass and soil pH,organic carbon,total nitrogen,nitrogen to phosphorus ratio,urease and invertase activity.There is a significant correlation between grassland vegetation community and soil pH,ammonium nitrogen,total phosphorus,urease and sucrase enzyme activities.The soil factors driving the alienation of plant communities in mild saline-alkali soils are total soluble salt,water content,nitrate nitrogen,total phosphorus,C/N,urease,and sucrase enzyme activities;the soil factors driving the alienation of plant communities in moderate and severe saline-alkali soils are pH,ammonium nitrogen and N/P.