Effects of fire history on thermal regimes of soils in the active layer and near-surface permafrost in the northern Da Xing’anling Mountains, NE China

In the northern Da Xing’anling Mountains in Northeast China, Effects of fire history on soil temperature, active layer thickness and soil moisture content. And the influence of different fire severity on thermal regimes of soils. The results showed that ground temperatures increased with increasing fire severity, and these changes mainly occurred at depths of 0–1.5 m. Moreover, nine years after a severe burn, the depth of evident temperature changes exceeded 6 m, and inferred warming of 2.7oC at 6 m depth. The onset of freeze-thaw processes in the active layer delayed at some severely burned sites, but advanced at some others. Presumably due to the influence of forest fires, the active layer thickness at severely burned sites was 3.8 m compared to 1.2 m at the un-burned site. Soil moisture content and organic-layer and snow-cover thicknesses also play important roles in further complicating the fire impacts on the permafrost environment.