砒砂岩区小流域林地土壤机械组成与分形维数关系

Relationship between Soil Particle Size and Fractal Dimension under Different Forests of a Small Watershed in the Feldspathic Sandstone Region

摘要:为了探究砒砂岩区不同林地土壤机械组成的差异,于鄂尔多斯市准格尔旗西部暖水乡境内的鲍家沟小流域选取立地类型一致的油松、侧柏、沙棘、柠条4种典型林地为研究对象,以天然草地为对照,每种林地设置样地3个,每个样地随机选取3个取样点,采集0~20 cm、20~40 cm和40~60 em土层土样,采用激光粒度分析仪测定土壤机械组成,分析各林地各径级土壤颗粒含量和分形维数之间关系。结果表明:油松林土壤颗粒最细.平均粒径值为3.591,其后依次是侧柏林@值2280)、羊草草地@值1.416),表明油松、侧柏林对于土壤细颗粒的保护能力相对较强;不同林地土壤细砂含量差异较大,分形维数与土壤机械组成综合指数的第一主成分呈线性关系(y=0.0129%+2.108,/为分形维数口为机械组成综合指数,P<0.05),与第二主成分呈二次项关系(y=0.036Q+0.00lx+2.27,y为分形维数"为机械组成综合指数.<0.05)。

To investigate the dynamic variations of soil particle size under different forests in the feldspathic sandstone region,different forest lands(Pinus tabuliformis,Platycladus orientalis,Hippophae rhamnoides and Caragana korshinskiias)were selected as the study areas and compared with grassland in the Baojiagou small watershed,Nuanshui Village,western Jungar Banner,Erdos,Inner Mongolia.Soil samples were collected from 0-20 cm,20-40 cm and 40一60 cm depths in the replicated plots under different forests and soil mechanical composition were measured hy the method of laser particle-size analyzer and its relationship with fractal dimension of soil particle were explored by the methods of principal component analysis and regression analysis.The results showed that soil particle diameter in Pinus tabulaeformis was the finest(3.591),then followed by Platycladus orientalis(2.280)and Caragana korshinskii(1.416),indicating that the fine soil particles were regulated or protected better under the arbor forest than under the shrubs and natural grassland.There was a large variation in fine-sands under different forests.Linear and quadratic correlation existed between the first principal component and soil mechanical composition(y=0.0129%4-2.108,y is the fractal dimension,and x is the composite index of mechanical composition P<0.05)and between the second principal component and soil mechanical composition(y=0.036%2+0.001%+2.27,P<0.05).