南昌不同城市化强度土壤粒度组成和分形特征及其影响因素

为探究南昌城市化强度对土壤粒度组成与分形特征的影响，将南昌市建成区按不透水面面积占比区分城市化强度等级取样调查（184个样方），测定土壤粒度组成、理化性质及植被指标，通过土壤颗粒体积分形维数模型计算分形维数值。结果显示：①南昌城市土壤颗粒以粉粒（46~59%）和砂粒（40~53%）为主，高城市化导致土壤中砂粒含量增加，粉粒含量减少。②南昌城市土壤分形维数的变化范围为2.69~2.97，随城市化强度增加呈下降趋势。土壤粉粒与分形维数正相关，砂粒与之相反，粉粒对土壤分形维数的影响最大。③皮尔森相关分析与结构方程模型分析结果共同表明：丰富的地上植被能够减少土壤颗粒的流失，改善土壤物理性质，缓解土壤退化；城市绿地中粉粒、极细砂粒等粒径适中的土壤颗粒保水、保肥更佳，更能反映土壤的质量水平。

Particle size composition and fractal characteristics of soils with different urbanization intensities in Nanchang and their influencing factors

To investigate the effects of urbanization intensity on soil particle size composition and fractal characteristics in Nanchang, the built-up area of Nanchang was sampled according to the impervious surface area as a percentage of the urbanization intensity level (184 plots), and soil particle size composition, physicochemical properties and vegetation indexes were measured, and fractal dimension values were calculated by the soil particle volume fractal dimension model. The results show: 1) the urban soil particles in Nanchang were dominated by silt particles (46-59%) and sand particles (40-53%), and the high urbanization led to an increase in the content of sand particles and a decrease in the content of powder particles. 2) The fractal dimension of Nanchang urban soil varied from 2.69 to 2.97, which showed a decreasing trend with increasing urbanization intensity. Soil silt particles were positively correlated with fractal dimension, sand particles were the opposite, and silt particles showed the greatest influence on fractal dimension. 3) The results of Pearson correlation analysis and Structural Equation Model analysis show that abundant vegetation reduces the loss of soil particles, improves soil physical properties, and mitigates soil degradation; Soil particles of medium size, such as powder and very fine sand, in urban green spaces can preferably retain water and nutrients and reflect the soil quality.