Edaphic Characterization, Water and Salt Translocation in Saline Marsh at Local Scale in Songnein Plain, Northeast China

摘要

The degradation of saline marsh in Songnen plain was controlled by many factors. Based on in-situ observation and laboratory analysis, soil properties and matters translocation in Zhalong wetland at local scale as affected by freeze and thaw action was explored. Results show that within the study plot, 1500 m in distance, but varying only 80 cm in altitude, existed four types of soils i.e. Shallow-horizon Alkalic Halosols (SAH), Crust Alkalic Halosols (CAH) and Para-alkalic Dark- Aquic Cambosols (PDC) and Sodic Hapli-Orthic Gleyosols (SHG). High content total porosity with amounts to 62% in surface horizon in marsh would help to water conservation and wetland formation. In contrast, large rate of silt or clay in texture in alkali soil and meadow soil constrain the water content in topsoil, i.e. the saturated water content 0-30 cm horizon of meadow soil and alkali soil were merely 0.83 and 0.7 m~3 m~(-3). Residues & roots in surface layer of SHG expand the period of freezing phase as long as 9 months comparing to 7 months in SAH, and maximum freezing fringe in the former was 24 cm deeper than the latter (178 cm versus 154 cm). Seasonal freeze and thaw action has obvious influence on water storage in topsoil in saline marsh, leading different of soil succession therein. Soil moisture content in the surface layer of marsh increased from 2.05 to 2.62 m~3 m~(-3)(over-saturated), but no obvious change in PDC and Alkali soils. In contrast, electrical conductivity of saturated paste in SAH and CAH increased from 6.5 to above 10 dS m~(-1). Therefore, it did not accord with the practical situation of Northeast China as that of strong evaporation was the only cause that caused saline marsh alkalinization. Protecting the vegetation or restoring surface coverage by plant in saline land in spring may help land dealkalization in high latitude arid & semiarid regions.