Study On Soil Physical And Chemical Properties And Water Repellent Properties Based On Fire Disturbance

In recent years, the global climate becomes abnormal, forest fires frequently, the area of forest reduces, and secondary disasters happen seriously. When we pay attention to forest fire prevention and forest ecosystem health protection, at the same time, how to fix the forest structure and productivity of the land, and restore the ecological function of forest soil, they become the most urgent to solve. Therefore, the south main secondary forest woodland as objects, it has important theoretical and practical guidance to carry out fire disturbance test, research the influence mechanism of soil water repellency with fire disturbance and how to restore the forest soil ecosystem. We are based on forest ecosystem health management, from the relationship between the structure of forest soil and function, we research the changing rules of PHysical and chemical properties in the southern secondary forest with fire disturbance, and analysis influence mechanism of forest soil water repellency after fire disturbance, and guide the soil restoration after forest fire, to provide theoretical basis for restoring the burns vegetationWith the help of NSFC, we set samples as fire interfere forests, and by diagonal set the sampling points,collect soil samples with soil auger, ring knife experimental equipments, etc. After that, number them and take back to lab for repetitive test 4 times (the data on paper is average of repetitive experiments for 4 times). Thereby we begin to research the changing rules of PHysical and chemical properties between different vegetation types and different soil depth, and the heterogeneity of soil water repellency under varying intensity of fire disturbance. The main research results as follows:Under varying intensity of fire disturbance, mixed forest with Pinus massoniana and Schima superb, four types of forests and so on, all the PHysical,chemical property and repellency of soils change, in addition, the fire disturbance intensity becomes higher, changes the more obviously, the soil depth becomes deeper,range ability is smaller. Of which the range ability of mixed broadleaf-conifer forest is obviously higher than secondary Liquidambar forest, as time varies, the indicators are restored to near interference levels, of which, Secondary Liquidambar forest restores the fastest.Under the same intensity of fire disturbance, the range ability of soil bulk density for different forest types decrease with vertical depth increases. Except low intensity fire disturbance, In a short time after fire disturbance, soil bulk density for different forest types all increase, while in a month after fire disturbance, it decreases rapidly, then slows down, difference becomes small until the sixth month; the fire disturbance intensity is higher, single grain size ratio greatly reduces in the soil for different forest types, small single grain size ratio increases; Except low intensity fire disturbance, on the surface of soil of mixed forest with Pinus massoniana and Schima superb, capillary pore, non capillary pore and the total pore ratio reduces with the fire disturbance intensity increases. Except low intensity fire disturbance, Surface (0～5 cm) soil maximum moisture capacity, capillary water holding capacity and natural moisture content, effective water content reduces with the fire disturbance intensity increasesAfter fire disturbance, forest soil water repellency significantly increases obviously in a short time, fire disturbance intensity is higher, the water repellency becomes stronger, the changing rules of other three forest types are the same as itFire disturbance has the greatest influence on surface soil PH of various forest types (0～5 cm), range ability of soil PH decreases with soil vertical depth increases. Low, middle and high intensity of fire disturbance results in soil organic losing for these four types of forests; fire disturbance intensity is higher, organic loses more, the influence depresses with soil depth increases.In the four types of forests, soil total N loss increases with the fire disturbance intensity increases, while total N restores the fastest after high intensity fire disturbance. With the increase of soil depth, the influence of fire disturbance on soil N decreases gradually. The soil under low intensity fire disturbance total P increases slightly. Under middle intensity fire disturbance total P decreases slightly, while under high intensity fire disturbance, the decrease range ability of total p is the biggest, total P decreases with the increase of soil depth. Total K increases with the increase of fire disturbance intensity, total K decreases with the increase of soil depth under the same fire disturbance intensity. In a month after fire disturbance, The five main properties on the soil surface behave positively correlate, means that the main properties of which spatial autocorrelation has a certain similarity; under middle and low intensity fire disturbance, the spatial autocorrelation is almost similar. Soil repelling water duration, PH, Total N and Total P under low, middle, high intensity fire disturbance accord with sPHerical model, while Total K accords with sPHerical model under high intensity fire disturbance, according with the linear model under middle intensity fire disturbance, according with Gauss model under low intensity fire disturbance.