作　　者： ; ; ; ; ; ; ;

机构地区： 华南农业大学林学院

出　　处： 《生态学报》 2011年第22期6824-6831,共8页

摘　　要： 通过与马尾松(Pinus massoniana)林(对照)对比的方法,研究了广东河源马尾松火灾4 a后土壤(0—20 cm)的物理性质、有机质和养分含量、土壤微生物及酶活性的变化,为了解火灾后的马尾松林土壤退化机理提供依据。火灾引起的土壤升温和灰分沉积改变了土壤的物理、化学和生化特性,造成了土壤质量的全面下降。火灾使土壤变得紧实,恶化了通气透水性。与对照相比,火灾的土壤容重显著增加了11%,土壤毛管孔隙比例增加了6%,非毛管孔隙和总孔隙的比例分别显著减少了30%和8%,土壤毛管持水量下降了5%,土壤中<0.01 mm粘粒的比例显著下降了16%。火灾通过氧化、挥发、淋溶和侵蚀等途径减少土壤养分含量。火灾对土壤pH影响不显著,仅下降了3%,但是土壤有机质、全N、全P和全K含量比对照分别减少了43%、29%、23%和36%,水解N、速效P和速效K含量分别比对照减少了43%、20%和47%,均达到极显著水平。火灾引起的高温和环境改变影响了土壤微生物的生存,火灾后的土壤细菌显著下降了16%,真菌和放线菌数量分别下降了3%和2%,土壤脲酶、土壤磷酸酶和过氧化氢酶活性分别比对照显著下降了46%、61%和19%。火灾通过氧化、挥发、淋溶和侵蚀等途径减少了有机质和养分含量,导致土壤孔隙减少,保持水分功能减弱,微生物数量减少和酶活性下降,引起地力衰退。 Fire is an important disturbance factor in many terrestrial ecosystems and plays a key role in shaping many forest systems around the world.Fire influences both above-ground and below-ground nutrient cycles by burning some of the vegetation,litter and duff,and therefore leads to nutrient losses.It can also cause important changes in the physical and chemical properties of forest soils including increased bulk density,and altered physical structure,soil moisture,pH and microbial populations.The degree of severity of the fire is largely dependent on the depth,moisture content and flammability of the forest floor material.During burning,nutrients can be lost to the atmosphere through volatilization and particulate transport.Because of its low volatilization temperature this loss includes most of the N.Fly-ash losses of P and K may be significant,although their volatilization temperatures are often higher.After the fire,nutrients are usually deposited on the soil surface in the form of ash,which may then be lost by wind or water erosion or leached into the soil.Wildfires are an important component of the historic disturbance regime of Pinus massoniana stands in south China,which can lead to important changes in the physical,chemical and biogeochemical properties of the soils under these stands.The effects of a wildfire on soil physical,chemical and biogeochemical properties（0 — 0.20 m） were studied in a field-scale experiment on a P.massoniana stand in Heyuan,Guangdong Province,China.We compared soil bulk density,porosity,capillary water,pH,soil organic matter,N,P,K,microbial populations and enzyme activity in unburned plots and in plots affected by wildfires burned over a 4-yr period,to understand the mechanisms involved in soil degradation in the burned P.massoniana stand.Wildfire significantly increased soil bulk density by 11%;slightly increased capillary porosity by 6%;and significantly decreased non-capillary porosity,total porosity and clay content by 30%,8% and 16%,respectively;whereas the soils＇ capi

关 键 词： 马尾松 土壤 物理性质 养分 微生物 酶活性

领　　域： [农业科学] [农业科学]