Study On The Ecological Stoichiometric Characteristics Of Plant And Soil In Different Diffusion Stages Of Sophora Alopecuroides Population In Yili River Valley

Grassland degradation seriously affects the increase of output of income of the farmers and herdsmen,as well as the ecological security of grassland.In the process of degradation,poisonous grasses expand,and fight for water and fertilizer from the fine herbage,affecting the quantity and quality of edible pasture.Sophora alopecuroides is one of the poisonous weeds in the degraded grassland of Yili.In recent years,it has widely spread out at the grassland of Yili river valley,farmland and other regions,endangering the ecological security of the valley grassland.Because of its fast propagation speed and rapid spread,the Sophora alopecuroides often forms a single superior community.So,Carrying out the study on the ecological stoichiometric characteristics of plant and soil in different diffusion stages of Sophora alopecuroides population in Yili river valley will help to fully understand the mechanism of the its proliferation in the arid and semi-arid areas,which is of important scientific research value and can provide important theoretical basis for the control of local poisonous grass.By using the ecological chemometrics methods and combining the processing of field investigation,sample collection,laboratory analysis and so on,this paper investigated the characteristics of the ecological stoichiometry of the widely spread Sophora alopecuroides in the degraded grassland of Yili,the rhizosphere soil aggregate of different diffusion stages of Sophora alopecuroides,the effect of the invasion of Sophora alopecuroides on the biochemical properties of rhizosphere soil,and the changes of active organic carbon in the rhizosphere soil of different diffusion stages of Sophora alopecuroides,so that to full understand the special mechanism of the propagation of Sophora alopecuroides as an invasive weed,and provide theoretical basis for the effective control of Sophora alopecuroides and the scientific management of the grassland in the arid and semiarid regions.The main results are as follows:?1?Average C,N,and P contents of Sophora alopecuroides to be 391.40,13.17,and 1.51 mg/g;the average ratios of C/N,N/P,and C/P were 45.61,8.52,and 326.38,respectively.The changes of the mean C,N,and P content showed the same pattern in the roots,stems,and leaves of Sophora alopecuroides during the completely growing season;leaves contained most of the nutrients,followed by stems and roots.However,they exhibited different patterns in the stoichiometric analysis.The C content increased with increasing plant growth,while N and P content declined.The content of C,N,and P in the root system of Sophora alopecuroides had a tendency to decline with the change in depth.The differences between organs indicated that the absorption and utilization of C,N,and P were specific to the plants during different growth periods.Plant leaves tended to have low C,N,and P content and N/P ratio.The growth of Sophora alopecuroides was limited by N and P jointly,but will be easier to constrain by N elements.?2?With the spread of the process,the particle size of sophora alopecuroides soil aggregate content of organic carbon,total nitrogen and organic carbon,total nitrogen,total phosphorus,stoichiometric ratio increased significantly,all show is in 0—20 cm soil layer is higher than 20—40 cm soil layer is higher than 40—60 cm soil layer,and total phosphorus content of soil aggregate of sophora alopecuroides changes smaller;The same series in 0—20cm,20—40cm,and 40-60cm soil were of the highest levels of organic carbon,total nitrogen,total phosphorus,and their stoichiometry.Build sophora alopecuroides to various soil aggregate particle size distribution of nutrient package and have positive influence on the equilibrium relationship,mainly reflected in 0.25—2 mm size of soil aggregate,by influencing the0.25—2 mm size aggregate can improve the soil nutrient supply for full effect and ability.?3?The root biomass,carbohydrate content,microbial biomass in top soil?0-10cm?of S.alopecuroidesplanted soil were significantly higher than those in local meadow;?2?S.alopecuroides stimulated the mineralization of organic nitrogen and carbon in top soil?0-10cm?;?3?The dehydrogenase,urease and phosphatase activity in S.alopecuroides planted soil was significantly higher than those in local meadow.In a word,S.alopecuroides changed soil biological and chemical property,making it beneficial for itsrowth,stimulating the expansion of it in Yili river valley grassland,severely influencing the development of livestock husbandry in Yili river valley grassland.?4?At 0—20 cm,soil microbial biomass carbon?MBC?,readily oxidized organic carbon?ROC?,dissolved organic carbon?DOC?,and mineralizable organic carbon?MOC?content under diffusion process of sophora alopecuroides were 0.21⁰.83g·kg^-1,3.08³.20 g·kg^-1,0.15⁰.34 g·kg^-1,and 0.04⁰.05 g·kg^-1,respectively.At 20—40 cm,the MBC,ROC,DOC,and MOC were 0.21⁰.79 g·kg^-1,2.70².96 g·kg^-1,0.12⁰.30 g·kg^-1,and 0.03⁰.04 g·kg^-1,respectively.In general,the MBC,ROC,and MOC were highest in summer and lowest in winter,whereas the DOC was higher in autumn than in the other seasons.Soil organic carbon content was significantly positively correlated with soil moisture,total nitrogen,total phosphorus,available nitrogen,and available phosphorus?P<0.5?.No significant correlation was found between soil organic carbon and available or total potassium.