Study On Soil Anti-scourability And Anti-erodibility Of Burned Area In Greater Xing’an Mountains

The effect of fire to forest ecosystem were extensive and complex, it not only reducing the biomass on the ground and burning out the litter layer, but also changing the change the physical and chemical properties of soil, and the growth of fine root in shallow soil. High-intensity fire can even lead to the degradation of soil structure, reduce soil anti-erodibility and soil anti-scourability, and lead to the loss of soil and nutrient, then cause soil erosion. In order to explore the occurrence of forest fires in 2 years, different intensity burned areas’soil physicochemical properties, soil anti-scourability and anti-erodibility changes, burned areas of three different fire intensities in Greater Xing’an Mountains were selected, and chose the adjacent unburned area as contrast. The results were as follows:(1) The different intensity of fire on soil physical and chemical properties were affected. The fire increased the soil bulk density, moderate burn changed on soil bulk density is the most, increased from 0.62g/cm3 to 0.82g/cm3. The fire had little effect on soil porosity,4 types of sample of the total porosity were in the range of 51.11%～56.76%. Fire made the soil water holding capacity decreased, the saturated water content, capillary water capacity and the field capacity of burned areas were lower than CK. Fire can make the soil pH increased, and with the strengthening of fire intensity increased. Content of soil organic matter in severe burned burned area was the highest among the three, except severe burned area, organic matter content decreased with the increase of the degree of fire, the trend were as follow:CK>mild> moderate. Fire intensity with initial permeability rate and the permeability coefficient is inversely proportional, with the steady infiltration time was proportional.The infiltration time of severe burned area was the longest, but the initial infiltration rate and infiltration coefficient was the lowest of four types of sample plots, soil permeability was the worst.(2) Fire can reduce soil anti-scourability, it was linear with the fire intensity of the soil, as the anti-scourability coefficient decreases with increase of fire intensity, the anti-scourability coefficient of severe burned area decreased from 10.29L·min/g to 0.40 L·min/g.(3) The effect of fire on soil disintegration rate showed a trend of that, with the increase of fire intensity, soil disintegration rate was increased, the order was severe> mild> moderate> CK, and 10～20cm layer soil disintegration rate was higher than 0～10cm layer.(4) The water stability index of three types of burned areas were less than the control plots, water stable index increases with decreasing degree of fire, soil water stable index changed slightly, ranging from 0.83 to 0.96. With the increase of soil depth, soil water stable index decreased 10-20cm soil layer water stability index range was 0.5～0.93.(5) Forest fire had an effect on structure characteristics of soil aggregates content and water stable aggregates.4 types of PA0.25 in the range of 72.35% to 85.36%, no significant changes. PAD0.25 of burned areas were higher than CK, the order was moderate>severe>mild >CK.Through this study, we can fill the domestic gaps in some areas of the effects of forest fire on soil properties in theory, to provide a reliable scientific basis for forest vegetation restoration and timely treatment of burned areas.