不同耕作措施下土壤孔隙的多重分形特征

MULTIFRACTAL CHARACTERISTICS OF SOIL PORE STRUCTURE UNDER DIFFERENT TILLAGE SYSTEMS

首先利用数字图像处理技术提取了东北黑土区长期免耕（no tillage,NT）和翻耕（moldboardtillage,MT）制度下土壤切片中的孔隙信息,然后应用矩方法研究了两种耕作制度下土壤孔隙结构的多重分形特征。结果表明,免耕降低了表层（0-5 cm）大孔隙度（〉500μm）,但是提高了10-15 cm和20-25 cm深度的孔隙度和大孔隙度。土壤孔隙结构在64-1 024像素尺度上具有多重分形特征。广义维（Dq）和多重分形谱（f（α））及相关参数能够反映切片中孔隙结构的特征。表层土壤孔隙多重分形谱明显右偏,随深度增加趋于对称。在同一深度下,免耕处理的Δα（α-10-α10）和ΔD（D-10-D10）均大于翻耕处理,免耕处理增加了孔隙结构的复杂程度,尤其是10-15 cm和20-25 cm深度下的孔隙结构。

Soil pore systems under no tillage（NT） and moldboard tillage（MT） in the black soil zone of Northeast China were extracted from soil thin sections with digital image process techniques and the multifractal characteristics of soil pore structure were studied with method of moment.Results indicate that NT decreased the macroporosity（500 m） in the surface layer（0-5 cm）,but increased the total porosity and macroporosity at 10-15 and 20-25 cm depth.Multifractal characteristics were observed at 64-1 024 pixel scales and generalized dimensions（Dq）,multifractal spectral（f（α）） and other related parameters reflected characteristics of the pore structure in the soil sections under NT and MT.The multifractal spectra of the pores in the surface layer apparently leaned toward the right side but approached to symmetry with increasing depth.Compared to MT,NT increased the Δα（α-10-α10） and ΔD（D-10-D10） of soil pore structure,and complexity of soil pore system,especially at 10-15 cm and 20-25 cm in depth.