Plant And Soil Characteristics Of Different Plots For Returning Farmland To Forest In The Middle And Lower Reaches Of The Yellow River

As one of the most valuable ecosystems in the world,wetland ecosystems play a key role in regulating climate,providing drinking water and agricultural irrigation water,and maintaining biodiversity,which is closely related to human survival,reproduction and development.Sustainable and healthy wetland ecosystem is not only the basis of the economic and social sustainable development,but also the guarantee of national ecological security.The Yellow River flows through nine provinces(districts)in China and accounts for one fourth of the country ’s annual economic output.As the second largest river in China and the fifth largest river system in the world,there are many soil,water,and biodiversity conservation conservation areas such as Taihang Mountain and the Yellow River Delta in the Yellow River basin.Therefore,the high-quality ecological conservation of the Yellow River greatly faciliates the economic development of the Yellow River basin and even China.Wetland ecosystems of the Yellow River basin,especially in the middle and lower reaches with the completion of large-scale water conservancy hubs,are facing great challenges in water pollution,soil erosion,riparian land salinization,ecological protection and other aspects.The formation of many abandoned farmlands has profound impact on the succession of soil and vegetation,and then the stability of the wetland system in the beach area.Therefore,the research on soil and plants in the wetland ecosystem of the middle and lower reaches of the Yellow River,aiming at the variation of plant diversity,plant and soil physical and chemical properties after abandoned tillage in different planting patterns of farmland in the middle and lower reaches of the Yellow River,not only provides scientific basis for the high-quality development of wetland ecology,but also faciliates soil development and plant protection in the middle and lower reaches of the Yellow River.In this study,the natural sample plots in the natural sample plots in the natural beach natural beach of the floodplain ecosystem in the middle and lowerreaches of the Yellow River were taken as the control and the plants and soil in the agricultural abandoned farmland plots as the research objects.Three transects were selected in the Taohuayu tidal flat study area.Five plots including natural beach plot(NT),abandoned farmland peanut plot(HS),abandoned farmland soybean plot(DD),abandoned farmland cabbage plot(BC),and fish pond surrounding plot(YT)were selected for field Investigation and sampling of plants(amarix chinensis,Phragmites australis,Glycine soja)and soil(0-10,10-20,20-30 cm)in the field,through indoor analysis :electrical conductivity(EC),water content,p H ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N),total carbon(TC),total nitrogen(TN),total phosphorus(TP),total potassium(TK),and organic carbon(SOC)were measured.Total carbon(TC),total nitrogen(TN),total phosphorus(TP),total potassium(TK)were anlaysized in plant roots,stems and leaves.Stoichiometric ratios of carbon to nitrogen(C/N),carbon to phosphorus(C/P),and nitrogen to phosphorus(N/P)were tested to study the process of typical plant succession and soil development in beach areas,as well as the relationship between soil and vegetation.The results show as below:1.The p H of abandoned farmland soil in the Yellow River beach area is between7.87and8.38,belonging to alkaline soil,soil EC,TC,TN and SOC showed a decreasing trend with the deepening of soil depth,soil nutrient content(TC,SOC,TN)mainly concentrated in the topsoil.The contents of TC and SOC in soybean abandoned farmland were significantly higher than those in other plots.Soil SOC was significantly positively correlated with TC,TN,TK and TP in each soil layer,but significantly negatively correlated with NO3--N and p H.2.The plant diversity of the reclaimed farming plot is significantly greater than that of the Nentan plot.Tamarix is mainly restricted by soil TN,wild soybean is restricted by soil SOC and TP,and reed is restricted by soil p H and NH4+,Wild soybeans and reeds maintain soil and carbon,while tamarisk maintains soil phosphorus and potassium.3.Soil C/N≈16:1,C/P≈27:1,N/P≈0.8:1 in the abandoned farmland in the middle and lower reaches of the Yellow River.The C/N and C/P of soybean abandoned farmland were significantly higher than those of other plots.The C/P of each soil layer in the abandoned farmland increased first and then decreased.The N/P of the abandoned farmland decreased gradually from surface soil to deep soil,and the peanut abandoned farmland was higher,but it was not significant with other plots.The contents of TC,TN,TP and TK in roots,stems and leaves of Tamarix chinensis,Glycine soja communis had no regular difference with stoichiometric ratios between different abandoned farmlands.The difference in the stoichiometric ratio of reed plants is mainly in the roots of the reeds.This paper aims to explore the main characteristics of soil and plants in the middle and lower reaches of the Yellow River beach area,the restriction and promotion mechanism between soil and vegetation,and to explore the secondary succession law of returning farmland in the middle and lower reaches of the Yellow River beach area,so as to provide reference and theoretical basis for the restoration of beach ecosystem and subsequent research.