民勤白刺灌丛沙堆演替过程中土壤粒径分形特征

通过野外采样与室内分析相结合，研究白刺灌丛沙堆在演替过程中土壤粒度与分形维数特征，分形维数与土壤粒级及土壤理化性质的关系。结果表明:1）民勤不同演替阶段白刺灌丛沙堆土壤均以细砂（46.71%～64.06%）为主；土壤分形维数变化为1.665～2.242，在白刺灌丛沙堆演替过程中分形维数呈现先升高后降低的趋势，衰退阶段达到最大值。2）分形维数与黏粒、粉粒、极细砂呈极显著正相关（P＜0.01），与中砂呈极显著负相关（P＜0.01），说明黏粉粒、极细砂含量越多，土壤分形维数越高。3）分形维数与有机质、全氮含量呈极显著正相关（P＜0.01），与速效磷含量呈显著正相关（P＜0.05），土壤分形维数可以用来评价土壤的养分状况。研究结果可为荒漠灌丛发挥防风固沙和土壤保育功能的定量化评价提供科学依据。

Fractal Characteristics of Soil Particle Size During Nitraria tangutorum Shrub Succession in Minqin

Through the combination of field sampling and laboratory analysis,the characteristics of soil particle size and fractal dimension during Nitraria tangutorum shrub succession were analyzed,and the relationship between fractal dimension and soil particle size and soil physical and chemical properties were studied.The results showed that 1) the soil of N.tangutorum shrub in different succession stages was dominated by fine sand (46.71%~64.06%); the soil fractal dimension varied from 1.665 to 2.242,during the succession,the soil fractal dimension firstly increased and then decreased,and reached the maximum in the decline stage.2) The soil fractal dimension had a very significantly positive correlation with clay,silt and very fine sand (P<0.01),and a very significantly negative correlation with medium sand (P<0.01),indicating that the more clay,silt and very fine sand contents,the higher the soil fractal dimension.3) The fractal dimension was significantly and positively correlated with organic matter and total nitrogen content (P<0.01),and with available phosphorus content (P<0.05).Soil fractal dimension could be used to evaluate soil nutrient status.The results could provide a scientific basis for the quantitative evaluation of desert shrub’s functions of wind prevention,sand fixation,and soil conservation.