| It is a significant technical measure of forest fire prevention that the low-intensity use of fire in silvicultur burns off leaves, reduces combustibles capacity, which not only can prevent the occurrence and spread of fire, but also improve the soil environment.This study selected core peripheral zone of Jiangxi Longhushan Nature Reserve. The sample areas are coniferous forest, broad-leaved forest and coniferous and broad leaved mixed forest. The use of fire in silvicultur experiment on January 2010. Experimental design:each 25m×25m forest type sample area is connected by its opposite diagonal and sampled as quincuncial form. Soil sampling depth:divide into 0～5 cm,5～10 cm,10～20 cm three layers, use core cutter method, reduplicate five times in each depth. Sampling time:take samples before the use of fire in silviculture, and take again in each three month 5 times as comparison. Measuring method of soil physical and chemical properties:use drying method to test soil moisture content and saturated moisture content, employ core cutter method to measure the volume weight of soil, adopt PH meter measurement for PH value, put to use "Hydration heat dichromate potassium oxidation-colorimetric method"to detect the soil organic matter, make use of FOSS DigiPREP TKN Systems to determine soil total nitrogen, take "Alkali-hydro-diffusion method" to assay soil rapidly-available nitrogen, apply "Sodium bicarbonate method" to admeasure soil rapidly-available phosphorus, and "Ammonium acetate leaching mention-Flame photometric method" for Soil rapidly-available potassium. We draw the following research results by outside sampling and indoor sample physical and chemical properties analysis:(1)The use of fire in silviculture has different effect on soil moisture content of the three forest type samples, reacts extremely difference on broad-leaved sample soil bulk density and saturated moisture content.(2) After the use of fire in silviculture, all the soil moisture contents decrease, but more obviously in superficial zone than in deep zone at different depth in the three types of soil samples. The soil moisture content decline markedly in Broad-leaved forest land, as falling off 7.04% on 0-5cm zone,5.49% in 10-20cm zone; the minimum is coniferous forest which is reflected in the data 7.04% in 0-5cm zone,3.12% in 10-20cm zone; the decreases in broad-leaved forest are 0-5cm zone 7.13% and 10-20cm 4.47%.(3) The volume weight of soil increase by 0.21g/cm3 at 0-5cm zone,0.17g/cm3 at 5-10cm zone, and 0.12 g/cm3 at 10-20cm zone in broad-leaved forest.(4) Coniferous forest land soil moisture content adds up 6.41% at 0-5cm zone, 4.82% at 5-10cm zone, but decreased 1.49% at 10-20 cm zone after the use of fire in silviculture, while broad- leaved forest drops 8.75% in three months,10.89% in six months,but returns to fire before in nine months at 0-5cm zone.(5) The use of fire in silviculture has significant difference on soil ph value, organic matter, total P and rapidly available N, rapidly available P and rapidly available K, but inapparent on total N and total K in the three types of soil samples.(6) Soil ph value increases obviously in three months use of fire silviculture, among the fastest one is coniferous forest, added 0.55 at 0-5cm zone,0.29 at 5-10cm zone,0.22 at 10-20cm zone.(7) Content of soil organic matter increases gradually in the three types of soil samples, among the most one is coniferous forest, which increases by 25.8491 mg/kg at 0-5cm zone,23.1132 mg/kg at 5-10cm zone and 21.6981 mg/kg at 10-20cm zone in one year use of fire silviculture.(8) Soil total N and rapidly available N increase in a short time in the three types of soil samples after the use of fire silviculture. In three month, broad-leaved forest increase faster than other two samples, in which total N adds to 0.0343% at 0-5cm zone, 0.0413% at 5-10cm,0.0543% at 10-20cm; rapidly available N raises to 66.202mg/kg at 0-5cm zone,61.98 mg/kg at 5-10cm zone, and 77.737 mg/kg at 10-20cm zone.(9) In three months use of fire silviculture, the total P and rapidly available P of all the three samples augment. Coniferous forest is the most obviously total P increase that it rises 0.01% at 0-5cm zone and 5-10cm zone, nearly 0.02% at 10-20cm zone, but reduces in three months. In coniferous and broad leaved mixed forest, rapidly available P increases by 0.4635mg/kg at 0-5cm zone,0.2756mg/kg at 5-10cm zone,0.5105 mg/kg at 10-20cm zone, but gradually decreases in six months.(10) In three months use of fire silviculture, soil rapidly available K increases promptly in coniferous and broad leaved mixed forest and broad-leaved forest. The most one is broad-leaved forest that increase by 2.6082 mg/kg at 0-5cm zone,0.5796 mg/kg at 5-10cm zone and0.5795 mg/kg at 10-20cm zone.Adopting low-intensity artificial control with fire can increase soil ph value, soil organic matter, N and rapidly available N, p and total p, k and rapidly available k, improve soil nutrient and contributes to enhance forest land fertility. |
