Field Simulation the Effects of Global Warming on the Freeze-Thaw Process of the Freshwater Marsh in the Sanjiang Plain, Northeast China

The freeze-thaw process in the marsh of the Sanjiang Plain, Northeast China was observed. The effects of the simulated global warming on the ice and snow thaw process and the influences of land-use/cover change on the freeze-thaw process of the freshwater mash soils were investigated. The effects of the water depth on the thaw of the soils beneath the water was also studied. In order to simulate global warming effects, ice and snow were covered by plastic films. The ice thaw process observation showed that the thickness of ice covered by film (FC) decreased by 35.29% more than that of the uncovered (UC). The surface snow temperature difference between FC and UC was not significant (t = 0.836, p = 0.408). The relationship between the temperature of a thawed soil layer (T) and the distance from the layer to the frozen borderline (D) follows the trend of the Logistic model (D = 6.30 - 4.57/1 + (T/10.59)^18.45, R² = 0.95) which can indicate that land-use/cover change has great effects on the freeze-thaw process in wetland. The results indicate that the global warming assumed in the future would seriously influence the freeze-thaw process of the freshwater mash and land-use/cover change have been greatly influencing the process, as well. On here, we only reported the first year´s results and the field simulation will be still going on.