Effects Of Spartina Alterniflora Invasion On Soil Sulfur Distribution And Sulfur-related Microorganisms In Jiuduansha Wetland

In the Jiuduansha area,the invasion of Spartina alterniflora will affect the diversity of the ecosystem,the geochemical cycle of the soil and cause serious damage to the ecosystem of the area.At present,the effects of Spartina alterniflora invasion on the sulfur form and sulfur-related microorganisms in the soil of Jiuduansha Wetland,and the resistance of Spartina alterniflora and the native species Scirpus mariqueter under sulfur stress are unclear.In this study,Jiuduansha Wetland Ecosystem was used as the research object,comparing the total amount of soil in mudflat,native species of Scirpus mariqueter and invasive plant Spartina alterniflora.The differences in the content of environmental factors such as organic carbon,total nitrogen,and total phosphorus were analyzed.The effects of plant invasion on the changes in the content of two sulfur forms(sulfide and sulfate)directly related to plant growth in the soil were analyzed.How plant invasion affects the structure of soil microbial communities in vegetation and functional genes involved in the soil sulfur cycle were also analyzed.Through indoor simulation experiments,the stress resistance between the invasive species S.alterniflora and the native species S.mariqueter under the different concentration gradients of sulfate and sulfide were compared.S.alterniflora invasion affects the impact of soil sulfide content and distribution on further plant invasion,thus systematically discussing the comprehensive effects and effects of Spartina alterniflora on soil sulfur transformation during the invasion process.This study helps to further understand the ecological consequences after the invasion of Spartina alterniflora,which provide theoretical guidance for the conservation of biodiversity in Jiuduansha area and the sustainable development of wetland resources.The main conclusions of this study are as follows:(1)Spartina alterniflora invasion will significantly affect the conversion of sulfur in the soil and change the distribution of sulfides.The average annual contentof sulfide in the soil of Spartina alterniflora community in the same area as S.mariqueter and mudflat gradually increased with the increase of invasion years.With the increase of invasion years,the content of sulfide in the soil of Spartina alterniflora vegetation showed a trend of decreasing first and then increasing;(2)The invasion of S.alterniflora has vertical distribution and seasonal effects on the transformation of sulfur in the soil.The content of sulfide in Spartina alterniflora generally decreases with increasing depth and then increases.The content of sulfide in S.mariqueter and mudflat appeared at the maximum at 40-60 cm.The soil sulfate content between different vegetation generally increased with increasing depth.In the soil covered by S.alterniflora vegetation,the soil sulfide content reached the maximum in autumn and the lowest in winter;(3)S.alterniflora will increase the content of total organic carbon and total nitrogen after its invasion,and it has a cumulative effect.Compared with S.mariqueter and mudflat,S.alterniflora soil has higher total organic carbon and total nitrogen content,showing a cumulative trend with the increase of invasion years.The14 th year of S.alterniflora invasion had the highest soil organic carbon content,which was 2.96 times and 3.53 times of S.mariqueter and mudflat,respectively.The14 th year of S.alterniflora invasion had the highest total nitrogen content,respectively.2.55 times and 2.88 times of S.mariqueter and mudflat;(4)The influence factors of sulfide and sulfate are different among different vegetation,and plant invasion will affect the original soil nutrition cycle.In the mudflat,total phosphorus and total iron have a greater impact on sulfide;in S.mariqueter vegetation,total phosphorus has a greater impact on sulfide;in S.alterniflora vegetation,total organic carbon,total nitrogen and water content have a greater impact on sulfide;(5)As the years of S.alterniflora invasion increase,the relative abundance of the two sulfur-reducing bacteria Desulfobulbaceae and Desulfobacteraceae will gradually increase,and the abundance of sulfur reduction function genes(dsr A + dsr B)in theearly and late stages of Spartina alterniflora invasion was higher than that of S.mariqueter and mudflat.;compared with S.mariqueter and mudflat,the relative abundance of Hydrogenophilaceae is lower,and the abundance of sulfur oxidation function genes(sox Y + yed Z)at different stages of S.alterniflora invasion is lower than that of native plant S.mariqueter;(6)Sulfide has a significant inhibitory effect on the root length,bud length and biomass of the seed growth of S.mariqueter,as well as the root length of S.alterniflora.Sulfate has an inhibitory effect on the root length and bud length of S.mariqueter seed germination,and it has an inhibitory effect on the root length of S.alterniflora.The inhibitory effect of sulfate on the growth of two plant seeds is significantly less than that of sulfide;(7)Increased sulfide concentration will reduce the activity of CAT and POD and soluble protein content in S.mariqueter,and reduce the SOD activity and soluble protein content in S.alterniflora.In the sulfate treatment group,the CAT activity of S.mariqueter will increase first and then decrease.The changes of POD,SOD and soluble protein are not significant.High concentration of sulfate will increase the soluble protein content of S.alterniflora,and the oxidase system has less influence than S.mariqueter;The POD activity,SOD activity and soluble protein content of Spartina alterniflora plants in the same treatment group were much higher than that of S.mariqueter.Under sulfur stress,S.alterniflora has stronger stress resistance than S.mariqueter.