Study On Dynamic Of Soil Moisture Content And Salinity And Its Influencing Factors In Coastal Saline Soil Under Humid Climate

It is very difficult for landscaping and ecological construction in the coastal saline areas because of the high salt content and shallow groundwater level. In order to solve the rapid landscaping of new beach reclamation in the coastal city, field experiment for the dynamic of soil moisture content and salinity and its influencing factors in coastal saline soil under humid climate were carried out in the Shanghai Chongming Dongtan Wetland ParkThrough long-term field monitoring for soil moisture content and electrical conductivity, the dynamic of soil moisture content and salinity in year was divided into four stages by the monthly variation of soil moisture content and electrical conductivity in different soil layer:strong salt accumulation period in spring (March to May), desalination period in rainy season (June to July), the second salt accumulation period in late summer and early autumn (August to October), desalination period in late fall and winter (November to February). The coupling relationship of soil moisture content and salinity was analyzed according to the spatial and temporal variability of soil moisture content and salinity.The results of field experiment for the relationship between hydro meteorological factors and soil moisture content and salinity showed that soil moisture content was mainly affected by the amount of water supplemental, soil salinity was mainly affected by the amount of water supplemental and groundwater.The field experiment results of the influence of vegetation types on soil moisture content and salinity distribution showed that vegetation obviously changed the vertical distribution pattern and dynamic of soil moisture content and soil electrical conductivity. Under different vegetation, soil moisture content was increased with soil depth, but the magnitude of change is different. Soil electrical conductivity was decreased with soil depth in wasteland, while it increased with soil depth under vegetation covered. Under different vegetation, the dynamic of soil moisture content in year was the same, while the soil salinity was quite different.The field experiment of the influence of different plantation age on soil moisture content and salinity showed that the improvement of Taxodium mucronatum Ten. on saline land was a positive constant feedback mechanism. In the whole soil layer (0-80cm), the order of soil moisture content and salinity was follow:CK>1a>4a>11a. There was no significant difference in soil moisture content, while significantly different in soil electric conductivity (P<0.05).The field experiment results of the influence of vegetation types on the spatial variation of soil moisture content and salinity showed that, when vegetation varied from N. indicum to T. distichum, the spatial heterogeneity of soil moisture content changed from weak to strong, which the variability was random in N. indicum. When the vegetation varied from C. dactylon to T. distichum, the spatial heterogeneity of soil salinity changed from moderate to strong correlation.The field experiment of the influence of plants on the spatial distribution pattern of soil moisture content and salinity showed that "salt island effect" were found in Ginkgo biloba L. and Taxodium mucronatum Ten., where the soil electric conductivity was highest in crown edge and gradually reduced toward standing trees and plant space. The soil moisture content was gradually increased from standing trees to plant space.This study systematically explored the dynamic of soil moisture content and salinity and the relationship between the influencing factors in coastal saline soil under humid climate, revealed the mechanism of the dynamic soil moisture content and salinity in the region. Its results has important guiding significance for the regulation of soil moisture content and salinity and landscaping construction in the region.