鲁中南山地典型植被土壤颗粒与土壤水分特征曲线的分形学特征

土壤粒径分布与水分特征曲线是土壤的重要物理性质,对土壤侵蚀状况和土壤肥力有显著影响。以鲁中南山地典型植被下土壤为研究对象,运用分形学理论研究5种典型植被土壤颗粒与水分特征曲线的分形学特征。结果表明:1)不同植被类型的土壤颗粒单重分形维数、多重分形参数和土壤水分特征曲线分形维数具有显著差异,均表现为麻栎+刺槐混交林>黑松+黄连木混交林>黑松林>核桃林>荒草地;2)土壤分形维数有林地大于荒草地,混交林大于纯林;3)土壤分形维数与黏粒体积分数、粉粒体积分数呈显著正相关,与砂粒体积分数呈显著负相关;4)土壤颗粒单重分形维数与土壤水分特征曲线分形维数呈显著的正相关关系。说明土壤颗粒分布与土壤水分特征曲线的分形参数可以作为反映土壤结构性状变化的定量指标,可利用土壤颗粒分形与土壤水分特征曲线分形维数的相关关系来描述对应的土壤水分特征曲线。研究成果可为鲁中南山地退耕还林与生态造林工程建设及其生态效益评价提供理论参考。

Fractal characteristics of soil particles and soil water retention curve under typical vegetations in mountainous land of central southern Shandong

Soil particle size distribution and soil water retention curve as important physical attributes had important effects on soil erosion and productivity. Based on fractal theory, fractal characteristics of soil particle size distribution and soil water retention curve under five typical vegetations were studied in mountainous land of central southern Shandong. Results indicate that： 1 ） Monofraetal dimension and multifractal parameters of soil particle and fractal dimension of soil water retention curve under different vegetation forms varied greatly, and all showed that： mixed plantation of Quercus acutissima Carr. and Robina pseudoacacia Linn. 〉 mixed plantation of Pinus thunbergii Parl. and Pistacia chinensis Bunge 〉 Pinus thunbergii Pad. 〉 Juglans rigia Linn. 〉 deserted grassland. 2） For the soil fractal dimension, woodland was significantly higher than deserted grassland, and mixed forest was higher than pure forest. 3） Fractal dimension of soil had a significantly positive correlation with silt and clay volume content, but a significantly negative correlation with sand volume content. 4） The monofractal dimension of soil particles had significant positive correlation with that of soil water retention curve. A well linear correlation was found between the monofractal dimension of soil particles and fractal dimension of soil water retention curve, which showed that fractal parameters of soil particle size distribution and soil water retention curve could be taken as quantitative indices to reflect soil physical properties. Relationship between fractal dimensions of soil particles and soil water retention curve could be used to describe corresponding soil water retention curve. The results in this paper could be a guidance and theoretical basis for the projects of the coversion of cropland to forest and ecological forest afforestation and their benefit evaluation.