Hydrothermal Changes and Physicochemical Characteristics of Subtropical Subalpine Soils under Freezing and Thawing

The soil column samples were collected for indoor simulated freeze-thaw experiments to monitor the soil hydrothermal dynamics and measure the basic physicochemical properties to research the effects of freeze-thaw on the hydrothermal process of peat bog soil and its relationship with physicochemical properties. The results indicate that in the initial phase of freezing-thawing, soil water content decreases and soil temperature changes, respectively. Unfrozen water content in soil in the stable freezing period decreases sharply. Compared with the freezing period, the fluctuation of soil moisture rate during thawing is more moderate with the temperature change. Soil ammonium nitrogen content decreases with decreasing soil temperature and is significantly positively correlated with soil water content after freeze-thaw, while total phosphorus, fast-acting phosphorus, total nitrogen and nitrate have no significant correlation with soil temperature and soil moisture content after freeze-thaw.