Distribution Patterns Of Plant Resources And Soil Carbon Storage In Coastal Wetland Of Chaohu Lake

Chaohu Lake wetlands play an important role in maintaining the ecological environment and promoting local socio-economic development due to their unique locations and habitats.At present,there are few studies on the correlation between plant diversity and soil carbon storage at home and abroad,especially for the Wetlands of Chaohu Lake.Therefore,it is of great ecological significance to study the characteristics of plant resources and soil carbon storage in order to provide support for the optimization and regulation of its ecological functions.Based on the investigation and analysis of the vegetation community composition,the wetland soil physicochemical parameters and carbon storage were studied systematically by the transect survey,the effects of water table gradient and different offshore distances on vegetation biomass,nutrients and soil carbon（C）and nitrogen（N）distribution patterns were analysed to reveal characteristics of wetland vegetation biomass,nutrients and soil carbon distribution patterns and their controlling factors across water table gradient and offshore distances,to clarify the dynamic coupling relationship between wetland habitat,vegetation structure and soil ecological function.The main results obtained are as follows.（1）The wetlands around Chaohu Lake are rich in plant species,with a total of 305species of vascular plants belonging to 218 genera in 78 families.The wetland vegetations includes two types:swamp forest and shallow water vegetation type groups and five vegetation types:swamp forest type,grass swamp type,floating vegetation type,floating leaf vegetation type,and submerged vegetation type.The dominant species are obvious,mainly including Phragmites australis（Cav.）Trin.ex Steud.,Nymphaea tetragona Georgi,Cynodon dactylon（L.）Pers.and Polygonum spp.,etc.In addition,the threat of invasive plants such as Alternanthera philoxeroides（Mart.）Griseb.,Solidago decurrens Lour.is gradually increasing,which have seriously effects on the living space of native plants.（2）Among the three major habitat conditions（shrub and beach habitat,forest habitat,estuary and riverside habitat）,the forest habitat had the largest vegetation biomass,and the soil physical and chemical indicators were significantly higher in forest land than in shrubs and beaches.There are significant differences in soil moisture,bulk density,p H,and EC values between soil layers.There were also significant differences between different sample lines.The content of ammonium and nitrate decreased significantly with soil depth and were significantly affected by changes of water tables.The content of the dissolved organic carbon（DOC）and nitrogen（DON）,microbial biomass carbon（MBC）and nitrogen（MBN）significantly decreased with soil depth,while there were no significant correlations with offshore distance.（3）The nutrient content in vegetation on Chaohu Wetland is generally in the order of K>N>P.The average content of each nutrient was N 16.41 g·kg^-1,P 1.32 g·kg^-1,and K20.51 g·kg^-1.The change of water table had a significant impact on the nutrient contents in vegetation,which fluctuated with different offshore distances.Plant C/P and N/P were significantly positively correlated with soil C/P and N/P.The change of water table had significant impact on vegetation biomass and carbon storage.（4）Theere were significant spatial variations of soil organic carbon content and soil organic carbon density（SOCD）.The SOCD ranged from 0.76 to 11.45 kg·m^-2,with an average value of 4.07 kg·m^-2.SOCD significantly decreased with soil depth,and was significantly positively correlated with soil moisture,K,Ca,Mg,N,C/P,N/P,while was significantly negatively correlated with soil bulk density and p H.Among the vegetation nutrient indicators,only plant P content showed a highly significant negative correlation with SOCD,while there was no significant correlation with plant C,N,C/N,C/P,N/P.（5）The structural equation model analysis showed that habitat type（p=0.005）,soil layer（p=0.027）,and offshore distance（p=0.002）had significant impacts on wetland soil SOCD.There were significant differences in SOCD among different transects,with forest land having significantly higher SOCD than the other habitat types.Different offshore distances significantly affected vegetation nutrients,biomass,and soil physical and chemical properties（bulk density,p H,EC）.The vegetation nutrients,biomass and soil physicochemical properties were significantly positively correlated with offshore distance,while soil nutrients（N,P,K,and C,N,P stoichiometric ratios）were significantly negatively correlated with offshore distance.Offshore distance significantly affects SOCD by affecting vegetation biomass,soil physicochemical properties and soil nutrients.However,although offshore distance significantly affected vegetation nutrients,it had not a significant impact on SOCD through vegetation nutrients.