Fractal Features Of Soil Particle Size Distribution And Hydrological Property Under Different Vegetation Communities In Hilly Area Of Middle Southern Region Of Shandong Province

Through the field plot investigation of the representative type of vegetation communities in hilly area of middle southern region of Shandong province(Meng mountainous area and Lu mountainous area), the article adopts the theories and means of vegetation community ecology, forest hydrology ecology and fractal geometry, carries on a research in soil particle fractal dimension, soil hydrologic-physical property and the relevance between them of different vegetation communities, describes soil particle composition and its relevance and hydrologic-physical property of different plant communities, reveals the correlation between soil particle fractal dimension and soil bulk density, pore space, infiltration rate, and announces the function degradation and rehabilitation features of vegetation communities structure under different human disturbance in the micro-scope, provides theoretic bases and technique supporting for the restoration and reconstruction of the soil and water conservation ecological rehabilitation.The main results are as follow:(1)different ecological forestland, economic forestland and farmland under human disturbance present different vegetation communities soil structure and hydro physical function.The unfavorable human disturbance such as grazing, bunting and over exploitation will heavily change this region soil structure and hydro physical function. Among them, the impact of farmland exploitation is much great, which the problem of soil harden is serious and water is hard to get into soil; grazing and bunting will also cause the forest soil hydro physical function reduce to a certain degree; the exploitation of economic forestland deeply impact the the water accumulation and containing ability of the soil layer. It will be revealed from the soil hydro physical improvement degree in different rehabilitation type vegetation communities of Meng mountainous area and Lu mountainous area: the measures of forbidding grazing and bunting and returning farm to economic forest for ecological forestland, economic forestland and farmland can promote good growth of vegetation on the ground and strongly improve soil hydro physical function, especially in the long-term banned ecological forestland.(2)In different land use types, a variety of vegetation communities in the degenerated succession process by the human disturbing, regardless of its soil physical properties or its soil layer hydrological effects, have taken place in different degrees of decline. The detail features of soil bulk density increasing, soil particle fractal dimension deceasing, soil pore space and water storage deceasing indicate that its soil compaction increases, uniformity of soil texture and fine-grained material decreases, soil water storage and pervious performance deceases.When the human disturbance is banned, the soil hydro physical properties are improved in varying degree in a variety of vegetation communities in the rehabilitation succession process of different land use mode and vegetation types. The detail features of soil bulk density of vegetation communities decreasing, soil particle fractal dimension increasing, soil pore space and water storage increasing indicate that its soil compaction decreases, uniformity of soil texture and fine-grained material increases, soil water storage and pervious performance increases.(3)There is a certain correlativity between the soil fractal dimension and soil hydro physical properties parameters. It is considered that the soil fractal dimension, as a comprehensive indicator of the quantitative description the nature of physical properties and hydrological aspects such as soil texture, density and pore structure (water storage), is with great research value and potential.In Meng mountainous area, soil fractal dimension shows a linear positive correlativity obviously between content of clay and silt, indicates a linear negative correlativity obviously with coarse sand content, gravel content and soil bulk density, but is not obvious relevance with fine sand. Soil fractal dimension shows a linear positive correlativity obviously between total soil porosity, capillary porosity and soil infiltration rate, but is not obvious relevance with non-capillary porosity.In Lu mountainous area, soil fractal dimension shows a linear positive correlativity obviously between content of clay, silt and fine sand content, but indicates a linear negative correlativity obviously with coarse sand content, gravel content and soil bulk density. Soil fractal dimension displays significantly linear positive correlativity with soil porosity (soil holding), and soil stable infiltration rate also showed some positive correlation, but not significantly.(4)Horton infiltration model and common experienced infiltration model both can better reflect the soil infiltration course and soil infiltration rate, closer to measured values,but the Philip model is bad relatively..This indicated Horton infiltration model and common experienced infiltration model applied to describe soil infiltration characteristics of the forest vegetation in research area.