草原火烧后土壤物理性状的变化

Changes of Soil Physical Characters Following Grassland Burning in a Hulunbeier Steppe

草原火烧后，当年春季土壤融化速度慢于未烧地，第二年春季的解冻融化速度快于未烧地．无论是火烧地还是未烧地，土壤融化均呈“快—慢”式节奏．火烧地春季含水量显著低于未烧地．火烧地表层土壤硬度高于未烧地，深层相反．春烧地和秋烧地表层土壤硬度低于未烧地和火烧地，深层硬度高于火烧地．火烧地土壤容重和密度发生变化，导致火烧地孔隙度明显高于未烧地．

Following grassland burning, melting speed of soil in the first year spring is slowly, reversly in the second year spring. Regardless of burned or unburned plot, they all indicated that melting speed of soil in spring is ‘fast-slow' way. Hardness of soil surface is higher in burned plot than in unburned plot,but it is lower in deep profile. The porosity of soil also is higher in burned plot than in unburned plot.