青土湖干涸湖底2种典型固沙植物群落土壤粒径分布分形特征与养分关系研究

以石羊河流域下游青土湖干涸湖底人工梭梭林和白刺灌丛沙包土壤为研究对象，通过分析2种植物群落5种立地条件土壤粒径分布和分形特征及其与土壤养分的关系，揭示了湖底2种典型植物群落土壤粒度的分布特征。结果表明:1）研究区固沙植被0~10 cm土壤颗粒以细砂粒为主，没有粗砂粒，其中白刺灌丛沙包表层极细砂含量、土壤颗粒物分形维数较梭梭林和对照区高。2）土壤颗粒分形维数与各粒级颗粒百分含量的关系差异较大，分形维数与黏粒、极细砂含量呈显著正相关，与细砂、中砂含量呈显著负相关，但是与粉粒含量关系不显著。土壤颗粒分形维数越大，土壤所含的细粒物质越多。3）土壤分形维数D值、黏粒、粉粒含量与有机质（SOM）、全N（TN）呈正相关性，土壤颗粒物的分形维数越大、土壤黏粒、粉粒含量越高，则土壤有机质、全N含量越高。综合分析，固定白刺灌丛表层土壤沙化程度相对较低，其他类型风蚀严重，因此，应积极采取生物措施和工程措施开展生态修复防治风蚀和盐尘暴的发生。

The Relationship between Fractal Characteristics of Soil Particle Size and Soil Nutrients of the Soils of Two Typical Sand-Fixing Plant Communities at the Bottom of the Qingtuhu Lake

In this paper,stand soils of two sand-fixing plant species,i.e.,Haloxylon ammodendron,Nitraria tangutorum that were planted in the dried bottom of the Qingtu Lake in the lower reaches of Shiyang River basin were taken as research objects to study the distribution and fractal characteristics of soil particle size in five sites of two plant communities and their relationships with soil nutrients,as well as the distribution characteristics of soil particle size in two typical plant communities.The results showed that 1) in 0-10 cm soil layer,soil particles were mainly fine sand in the study area,accounting for 65.9%,without coarse sand,the content of extremely fine sand and fractal dimension D in the surface of the N.tangutorum were higher than H.ammodendron and the mobile sand dunes.2) The relationship between soil fractal dimension and percentages of different grain sizes was significantly different.Fractal dimension presented significantly positive correlations (P<0.05) with the contents of clay and extremely fine sand,and significantly negative correlations (P<0.05) with the contents of fine and medium sand,but there was no significant relationship with the content powdery particles.The larger the fractal dimension of soil particles,the more fine grains (clay and very fine sand) in the soil.3) Fractal dimension value (D),soil clay and particle content were positively correlated with soil organic matter and total nitrogen.The higher the fractal dimension of soil particles,the higher the soil clay and particle contents,the higher the soil organic matter and total nitrogen contents.Based on the comprehensive analysis,the content of extremely fine sand and fractal dimension of N.tangutorum were high at the bottom of Qingtu Lake,which could reflect the serious wind erosion degree of the site type,so biological measures and engineering measures should be taken actively to prevent and control wind erosion and salt dust storm.