Research Of Restoration Methods Of Tidal Flat Vegetation Based On Benthic And Soil Conditions

Tidal flat wetland is one of the most productive systems in the world,which has many ecological service functions,including providing nutrients and habitats,protecting beaches and fixing sand,nutrient filter,buffer adjustments and carbon sequestration.Spartina alterniflora invaded the tidal flat ecosystem,which affected the composition and richness of benthic animals,changed the tidal water-salt interaction process,changed the soil physical and chemical properties,and affected the vegetation distribution pattern,resulting in great differences between the ecosystem and the indigenous ecosystem.These points are the important reasons for the functional degradation of the tidal flat ecosystem.Based on this,in Dafeng Elk National Nature Reserve and Yancheng National Rare Bird Reserve,Jiangsu Province,controlled experiments and in-situ observation were carried out to study the relationship between benthic disturbance and soil factors,soil salinity and plant growth,and the corresponding relationship between secondary bare land plant community and soil factors,so as to explore the ways of coastal wetland vegetation restoration based on benthic disturbance and soil factor regulation.The results revealed that:(1)Through the comparative analysis of the relative size,variation trend and significant correlation factors of main soil factors among multi-crab group,less crab group and control group showed that benthic animals disturbance had relatively little influence on soil bulk density(BD)and salinity(DS),but had relatively high influence on soil total nitrogen(TN),total organic carbon(TOC)and total phosphorus(TP).There is a positive correlation between the number of crab caves(CAV)and the aboveground biomass(AGB)of plants.Increasing the intensity of soil bioturbation may promote the aboveground biomass of plants in Spartina alterniflora community.The differences of soil factors among sampling points of different treatment groups in different seasons vary with treatment time.At the beginning of the experiment,the differences of soil factors among different treatment groups are small.With the extension of treatment time,the differences of soil physical and chemical properties are increasing.The multi-crab group corresponds to higher soil BD,lower TOC,TN,the less crab group corresponds to higher soil TOC,TN,lower BD,and the control group corresponds to higher DS,TP.There is a phenomenon of soil characteristic differentiation among groups.The results showed that through the regulation of benthic animal activities,the status of soil factors and the relationship between soil factors could be changed,and the spatial differentiation of soil microhabitat could be promoted,thus affecting the community characteristics.(2)Under the same treatment of Spartina alterniflora community(cutting the aboveground part and the primary),the plant height,coverage and number of plants in the three soil depths of the cutting group were significantly lower than those in the sample plots without salt,while the plant coverage and number of plants in the sample plots with salt in the surface and middle layers of the uncut group were significantly lower than those in the sample plots without salt.Under the same soil depth and salt treatment,the mowed group was lower than the uncut group in plant height,coverage and number of plants.By cutting Spartina alterniflora and increasing soil salt,the surface aggregation of soil salt was strengthened.The input of exogenous salt can improve the salinity of soil surface and middle layer and moderately inhibit the growth of Spartina alterniflora in a short time.(3)Secondary bare land succession formed early mosaic community.Among all soil factors,soil moisture content(SMC),bulk density BD,total nitrogen TN had great differences among different plant communities and soil layers of each community,followed by TOC,DS,TP and p H differences are relatively small.The difference of soil characteristics among different plant communities decreased with the increase of soil depth.The corresponding relationship between plant communities and soil factors is different due to soil factors and community types.The properties of topsoil can better reflect the corresponding relationship between soil and plant community,and SMC,DS,TN,TOC have great correlation with the change of plant community characteristics.High content of TN,TOC,SMC and low content of BD correspond to Spartina alterniflora community,high content of BD,DS and low content of TOC,SMC correspond to Suaeda salsa community,and high content of TP,p H and low content of DS correspond to Phragmites australis community.In the secondary bare land,the microtopography significantly affects the soil factors,and becomes the key differentiation factor for the differences of plant community composition characteristics in different microtopography units.In the early stage of community succession,the process of vegetation restoration in secondary bare land can be effectively controlled by influencing soil factors through micro-geomorphic characteristics.To sum up,this study can provide theoretical basis for ecological restoration of coastal wetland vegetation based on the benthic animal regulation,soil factor regulation and micro-geomorphology unit construction.