海涂围垦区不同土地利用类型土壤颗粒分形特征

Fractal features of soil particles under different land uses in a coastal reclamation area

土壤颗粒分形特征是表征植被与土壤环境相互作用的重要因子。本研究以江苏沿海条子泥垦区长期撂荒地和水稻田两种土地利用类型为研究样地,探讨了土壤颗粒分形维数及其与土壤粒径分布、土壤理化性质之间的关系。结果表明:海涂围垦区土壤颗粒分形维数在2.16~2.21之间,不同土地利用类型间分形维数存在显著差异,表现为荒地土壤大于稻田土壤,农业垦殖降低了海涂垦区土壤颗粒分形维数。土壤颗粒分形维数与土壤黏粒、细粉砂粒和粗粉砂粒的颗粒含量呈极显著正相关,与极细砂粒、细砂粒和中砂粒的颗粒含量呈极显著负相关。粒径0.05 mm是影响海涂围垦区土壤颗粒分形维数变化的临界粒径。荒地土壤电导率和可溶盐阳离子含量均高于水稻田土壤,水稻种植有利于降低围垦区土壤盐分含量。土壤颗粒分形维数与土壤有机质含量和粒径>0.25 mm水稳性团聚体含量均呈显著正相关关系。土壤颗粒分形维数可以较好地反映土壤理化性质特征及变化过程,可以作为评价海涂围垦区盐渍土发育和演变规律的定量指标之一。

The fractal feature of soil particles is an important factor to characterize the interaction between vegetation and soil environment.In this study,the fractal dimension of soil particles and their relationship with soil particle size distribution and soil physical and chemical properties were studied in terms of two land uses,long-term abandoned land and paddy field in a reclamation area along the coast of Jiangsu Province.The results showed that the fractal dimension of soil particles in coastal reclamation area was between 2.16~2.21,and there was significant difference between these two land uses.The fractal dimension of soil particles in the wasteland soil was larger than that of the cultivated soil,and agricultural reclamation reduced the fractal dimension of soil particles in the coastal reclamation area.The fractal dimension of soil particles was positively correlated with the clay,fine silt and coarse sand,but negatively correlated with the content of very fine sand,fine sand and medium sand.The particle size of 0.05 mm was a threshold size that affected the fractal dimension of soil particles in the coastal reclamation area.The electrical conductivity and soluble salt cation content of wasteland soil were higher than those of paddy soil.Rice farming was beneficial to reduce the soil salt content in coastal reclamation area.The fractal dimension of soil particles was significant positively correlated with the organic matter content and the contents of water-stable aggregates with particle size>0.25 mm.The fractal dimension of soil particles could be used as one of the quantitative indicators to represent the characteristics and changes of soil physical and chemical properties,and to evaluate the development and evolution of saline soil in coastal reclamation area.