豫西石质丘陵区不同土地利用方式下土壤颗粒分形特征

运用分形理论,以豫西石质丘陵区土壤为供试材料,分析了天然次生林、荒草地、混交林、杨树林、耕地等5种土地利用方式的土壤颗粒分形特征及其与土壤各粒级含量、理化性质之间的关系。结果表明:1)研究区土壤细粒化较明显,具有一定的水土保持效应;2)5种用地方式分形维数平均值介于2.510～2.629之间,分维值大小依次为天然次生林>耕地>杨树林>混交林>荒草地,可以在一定程度上反映石质丘陵区水土流失的程度;3)土壤颗粒分形维数与土壤颗粒含量存在较强相关性,即土壤中黏粒含量越高,尤其是0.002～0.001 mm粒级含量越高,分形维数越大;4)研究区土壤颗粒分形维数与速效钾含量呈显著正相关,与其它理化性质的相关性均不明显。

The Fractal Features of Soil Particle Size Distribution under Different Land Use Practices in the Lithoidal Hilly Area of Western Henan Province

Taking soil samples in the lithoidal hilly area of Western Henan as test materials,a case study on the soil particle fractal features of natural secondary forest,wild grassland,mingled forest,poplar plantings and farmland was conducted.And the relationships between fractal dimension of soil particle distribution and selected soil properties have been discussed.The results show that:(1)There exists an obvious trend that soil particles become small in study areas,which has certain effects of soil and water conservation.(2)The fractal dimensions of soil particles under these five land use types range from 2.510 to 2.629,the average fractal dimension of soil particle of natural secondary forest is highest,followed by farmland,poplar plantings,mingled forest and wild grassland,that is to say,the soil particle fractal dimension can reveal the level of soil erosion of lithoidal hilly area in some extent.(3)There is some relationship between soil particle content and its fractal dimension,and it positively correlates with the contents of clay,the fractal dimensions of the soils have significantly positive correlations with the contents of soil particles in size of 0.002~0.001 mm,namely the higher the contents of clay,the bigger fractal dimension of soil particles.(4)Soil particle fractal dimensions only show significant positive correlations with the content of available K,but with other physicochemical properties they did not show any.