Effects of snow cover and freeze-thaw cycles on stability of surface soil aggregates in forest

Snow cover is an important ecological factor that can affect soil freezing-thawing process by changing the heat exchange between atmosphere and soil, and therefore impact soil aggregates. We conducted laboratory incubation experiment and field sampling to study the effects of snow cover and freeze-thaw process on the stability of soil aggregates in three types of forest in Changbai Mountains, northeast China. The results showed that: 1) the winter freeze-thaw process significantly decreased the stability of soil aggregates in the mature broad-leaf forest (P<, 0.01), but did not significantly affect that of the young broad-leaved forest and mature broad leaf-Korean pine mixed forest. The stability of soil aggregates was significantly affected by freeze in winter and freeze-thaw process in spring. 2) Snow cover in advance can prevent soil freeze-thaw process in early winter and freezing in winter and therefore significantly increase aggregate stability value, but cannot prevent the decrease of soil aggregate stability value during the spring freeze-thaw process. 3) Forest type, freeze-thaw cycles and water content significantly influence soil aggregates stability. In conclusion, the soil aggregates stability can be affected by the global climate changes such as climate warming and precipitation pattern change through changing factors like snow cover, soil temperature, and soil moisture.