辽西半干旱区森林土壤大孔隙特征研究

根据水分穿透曲线和Poiseulle方程,研究了辽西半干旱区8种植被类型下土壤大孔隙的半径范围、个数及分布情况。结果表明,不同植被下土壤大孔隙半径分布在0.5～2.3mm,加权平均半径在0.61～1.85mm,均值为0.95mm,均值为粗通气孔隙标准的近2倍,>1.4mm的特大孔隙仅为大孔隙总数的2.73%,0.5～1.4mm的孔隙占97.27%,表现出大半径孔隙少而小半径孔隙多的特点。不同植被下土壤大孔隙度在0.95%～5.24%,仅占土壤体积很小的一部分,但大孔隙平均半径与稳定出流速率和饱和导水率之间有显著线性相关关系,决定了稳定出流速率71%的变异和饱和导水率50%的变异。

A Study on Macropore Properties of Forest Soil in Semi-arid Region of Western Liaoning Province

The radius, number and distribution of soil macropores under eight types of vegetation in the semi-arid region of western Liaoning Province were investigated using water breakthrough curve and Poiseulle equation. Results showed that under the different vegetations, the radii of soil macropores ranged from 0.5 to 2.3mm; weighted mean radii varied from 0.61 to 1.85mm ; and the overall mean value was 0.95mm, nearly two times the coarse aeration porosity standard. The macropores with the radius larger than 1.4mm accounted for only 2.73% of total macropore number and between 1.5 and 1.4mm, 97.27%, which showed that large radius pores were more than small radius pores. Soil macroporosity under the different vegetations ranged from 0.95% to 5.24%, which means that soil macropores constituted a small portion of soil volume. However, the mean radius of soil macropores was significantly correlated with steady effluent rate and satu-rated hydraulic conductivity. The mean radius determined 71% variances of steady effluent rate and 50% of saturated hydraulic conductivity.