Experimental study on soil fire temperature field of harvested site of Larix olgensis plantation.

We established a fire simulation experiment in the harvested site of Larix olgensis plantation and recorded the temperature of each test point at 500, 1000 and 1500 s during the fire by thermocouple temperature measurement. The data were displayed in the form of images to show soil temperature field at each layer during the fire. The results showed that when the wind speed was less than or equal to 2 m·s or greater than or equal to 10 m·s, combustibles could not be fully burned. In the case of full combustion of combustibles, soil temperature at each layer was the highe-st when the wind speed was 6 m·s, with the affected soil depth being up to 12 cm or more. The maximum temperature at soil layer of 3 cm could reach 300 ℃. Compared with that at the non-cut stump, soil at the stump had a higher maximum temperature during the fire, with the soil temperature being higher near the stump. When the wind speed was 6 m·s, the temperature range at soil layer of 3 cm from the farthest and the nearest to the stump was from 198 ℃ to 315 ℃. With the deepening of soil layer, soil temperature sharply decreased. The temperature at the soil layer of 15 cm was almost unchanged during the fire test. The temperature at the soil layer of 12 cm was increased only when the wind speed was 6 m·s, and the temperature at the soil layer of 3 cm was the highest. When the wind speed was 6 m·s, the influence of fire on the soil temperature was the greatest, and soil at stump had the severest damage.