Abstract: In order to explore the relationship between soil structure and soil stability of Artemisia ordosica community in Mu Us sandy land, this paper analyzed the characteristics of soil particle size and its related factors. The results showed that the soil particle under the canopy of Artemisia ordosica was mainly composed of sand, accounting for 90.23% of the total, then powder, 8.31%, clay content of the least, 1.46%. The average content of organic matter and total nitrogen were 2.67 g/kg, 0.12 g/kg, respectively. Influenced by the morphological and structural characteristics of Artemisia ordosica, the soil composition and nutrient status under the canopy of Artemisia ordosica were different in different directions, and the same direction with different distance. The fractal dimension of soil particles under the canopy of Artemisia ordosica were between 1.689 and 1.860, which had a significant negative correlation with sand content (P<0.05), and a positive correlation with powder (P<0.05), clay, and total nitrogen, respectively. There was an extremely positive correlation with organic matter (P<0.01). Soil microaggregate as the basic unit of soil structure and main carrier of soil nutrient, its content and composition are closely related to soil fertility and erosion resistance. So, during the process of restoration and reconstruction of Artemisia ordosica community, more attention should be paid to the characteristics of soil particle in the microenvironment-under the canopy of Artemisia ordosica.

Key words: Mu Us sandy land, Artemisia ordosica, soil particle, fractal dimension, influencing factor

摘要： 为探索毛乌素沙地油蒿群落土壤结构与土壤稳定性的关系，分析了油蒿植冠微环境下土壤粒径特征及其相关因素。研究表明：油蒿植冠下土壤机械组成以砂粒（90.23%）为主，其次是粉粒（8.31%），粘粒含量（1.46%）最少，有机质平均含量2.67 g/kg，总氮平均含量0.12 g/kg，受油蒿植株形态结构特征等因素影响，油蒿植冠下不同方向、同一方向不同距离处土壤颗粒组成及养分状况存在差异；油蒿植冠下土壤颗粒分形维数在1.689~1.860之间，土壤分形维数与土壤砂粒含量呈显著负相关（P<0.05），与土壤粉粒、粘粒、总氮含量呈显著正相关（P<0.05），与土壤有机质含量呈极显著正相关（P<0.01）。土壤微团聚体作为土壤结构的颗粒单元、土壤养分的主要载体，其含量及组成与土壤肥力、抗侵蚀性密切相关，在对油蒿群落进行恢复重建过程中，要充分考虑油蒿植冠下微环境土壤粒径特征及其影响。

关键词: 毛乌素沙地, 油蒿, 土壤粒径, 分形维数, 影响因素