The Impact Of Invasive Smooth Cordgrass(Spartina Alterniflora Loisel.) On Soil Sulfur Stock In Jiuduansha Wetland

In this study,sulfur distribution of exotic Spartina alterniflora、native Scirpus mariqueter and the rate of litter decomposition were researched in Jiuduansha wetlands.The object was to explore the impact of invasive S.alterniflora on sulfur storage,further improve our understanding about whether the invasion of S.alterniflora was beneficial to the sulfur function of Jiuduansha wetlands.Therefore,it was conducive to providing theoretical guidance and decision basis for function management of Jiuduansha wetland,which is considered to be sulfur sink.This study combined the field survey and laboratory analysis.We sampled in January,April,July October in 2016,determined sulfur storage from different plant species and sediments and analyzed soil microbial community structure.In addition,we carried out a traditional decomposition bag study to compare the decomposition rate differences of the native plants and invasive S.alterniflora.The results are as follows:(1)Sulfur concentration of S.alterniflora community plants changed regularly with the increase of invasion time,and showed an overall growth trend.Sulfur concentration of S.alterniflora plants was significantly higher than that of Scirpus mariqueter(2)There was a significant difference in sulfur concentration in different community tissues.Sulfur concentration in S.alterniflora plants was significantly higher than that of native Scirpus mariqueter,and showed significant seasonal changes.The relationship between sulfur concentration in S.alterniflora tissues was: leaf> root> stem.(3)The decomposition rate of Spartina alterniflora litter was higher than that of Scirpus mariqueter,,and the litter decomposition rate of the same plant was higher than that of aerial litter.(4)The decomposition rate of plant litter is affected by the vegetation species,decomposition phase and decomposition time.The interactions between vegetation types and the relative decomposition rates of vegetation were significantly affected.At the same time,the interactions between vegetation types and decomposition times on decomposition rates were also significant.(5)Carbon and nitrogen concentration in litter played a key role in the decomposition and releasing of sulfur.There was a significant negative correlation between the release rate of sulfur in litter and C/N value.(6)There was a significant difference in soil sulfur concentration between different community wetland,and the sulfur concentration in the soil was obvious in native Scirpus mariqueter and mudflat,and the accumulation of S.alterniflora with the increase of the invasion years.(7)Sulfur concentration in the soil of Spartina alterniflora showed obvious seasonal changes,with the highest sulfur concentration in spring and the lowest in summer.In the depth of the soil,there was a change of first increase and then decrease,with the highest concentration at 40-60 cm and the lowest at 20-40 cm.The average sulfur concentration was 1.9 and 2.1 times higher than that of the Scirpus mariqueter and mudflat.(8)The difference in soil sulfur concentration between the native Scirpus mariqueter and mudflat was not significant at different depths in different seasons,and the fluctuation was not significant.The soil concentration of the Scirpus mariqueter community was slightly higher than that of the non-vegetated mudflat.(9)There was a significant positive correlation between soil sulfur concentration and soil total carbon concentration in Jiuduansha wetland community,and a significant negative correlation with soil total nitrogen concentration.(10)The richness and evenness of soil microbial species in the Scirpus mariqueter community were higher than that in the Spartina alterniflora community,but the abundance of sulfur-associated functional microbes was higher in the latter than in the former.The most dominant species of soil microorganisms in the Spartina alterniflora community was the desulphatobacter,which was different from the microbial community structure of Scirpus mariqueter and mudflat,and both were higher than the latter two.(11)With the increase of invasion times of Spartina alterniflora,the abundance of sulfate-reducing bacteria in the soil first increased and then decreased,but it was significantly higher than that of Scirpus mariqueter and mudflat.In the Spartina alterniflora community,with the increase of soil depth,the abundance of S-functional microorganisms in the soil decreased first and then increased,which was consistent with the changes in soil sulfur concentration.