华北土石山区森林土壤中石砾分布特征对土壤大孔隙及导水性质的影响

为了探究土壤中石砾对大孔隙形成的作用及对饱和导水率的影响,研究京郊密云水库水源涵养林内土壤石砾分布特征、大孔隙分布特征以及与饱和导水率之间的关系。结果表明:(1)林区0—30cm土壤层内石砾体积含量范围为7.10%~22.05%,质量含量范围为10.76%~38.20%,且石砾多集中分布于5~10mm粒径范围内;石砾含量随坡向呈现阳坡阴坡半阴半阳坡的规律;(2)石砾含量与当量孔径1.5mm的孔隙密度呈现极显著相关关系(p0.01),粒径5mm的石砾体积含量与大孔隙密度具有显著相关性(p0.05),说明砾石主要影响较大孔隙,特别是粒径5mm的石砾对大孔隙的形成影响较大;(3)当量孔径1.5mm的孔隙数量仅占总孔隙数量的1.41%,但对导水速率的贡献率为54.44%;饱和导水率与其呈线性关系。

Effects of Distribution of Rock Fragment on Macropores and Saturated Water Conductivity in Forest Soil in Rocky Mountain Area of Northern China

The content of soil stone is rich in the rocky mountain area of North China, which has an important influence on the macropores and water transport. The study was carried on Miyun reservoir in Beijing, in order to explore the relationship among stones, macropores and the soil saturated hydraulic conductivity. The results showed that: (1) Volume content of stone is in the range of 7.10%~22.05%, while mass percent is range from 10.76% to 38.20%. Stones in the size of 5~10mm has highest content in soil. The percentage composition of stone with the slope aspect has regulation as follows: adret slope > semi shaded slope> shade slope; (2) The macropore density of equivalent pore >1.5mm showed very significant correlation relationship with stone content (P<0.01).The volume content of stones with the size >5mm has a significant correlation relationship with macropore density (P<0.05). It illustrate that stones mainly affect macropores with large size, and stones in size of >5mm have a key influence on the formation of macropores. (3) The amount of equivalent pores with size >1.5mm only accounted for 1.41% of the total macropores, but determined the 54.44% of the saturated conductivity. The hydraulic conductivity and the amount of equivalent pores with size >1.5mm has a linear relationship. Exploring the relationship among stones, macropores and saturated hydraulic conductivity can provide a comprehensive understanding of forest soil and water conservation mechanism and hydrological adjusting process. It can also provide theoretical basis to the water resource utilization and protection in Rocky Mountain, and the establishment of hydrological process model.