荒漠草原不同植被微斑块土壤粒径分布分形特征与养分的关系

Fractal dimension characteristics of soil particle size distribution under different vegetation patches in desert steppe and its relationship with soil nutrients

采集宁夏中部干旱带荒漠草原4种植被(猪毛蒿、甘草、苦豆子、草木樨状黄芪)微斑块土壤剖面3个层次土壤,测定了各微斑块土壤颗粒粒级分布、有机质、pH值、土壤电导率(EC)、全氮、全磷和全钾等理化性质,探讨了不同植被微斑块土壤粒径分布的分形维数(D)特征及其与土壤理化性质的关系.结果表明:斑块化植被分布可影响土壤粒径分布,其影响作用以草木樨状黄芪微斑块最大(D=2.51),甘草微斑块最低(D=2.46);分形维数与黏粒、粉粒含量呈显著正相关,而与砂粒含量呈显著负相关;土壤粒径分布分形维数与pH和EC呈显著正相关,与有机质和全氮含量呈显著负相关,与全磷和全钾含量无显著相关关系.斑块化植被分布有潜在土地盐碱化和土地退化的趋势.

Soil samples from four vegetation mini-patches(Artemisia scoparia, Glycyrrhiza uralensis, Sophora alopecuroides, Astragalus melilotoides) in a desert steppe in central Ningxia were collected. Soil physico-chemical properties including soil particle-size distribution, organic matter, pH, EC, total N, total K, total P of three depths were measured. The fractal dimension of particle size distribution characteristics of soils derived from four different vegetation mini-patches and their correlations with soil physico-chemical properties were examined. The results showed that patch vege-tation distribution affected the distribution of soil particle size, with the A. melilotoides mini-patch being the highest(D=2.51) and G. uralensis mini-patch being the lowest(D=2.46). There were significant positive correlation between fractal dimensions and the contents of clay and silt, and nega-tive correlation between fractal dimensions and sand content. Fractal dimensions were positively correlated with pH value and EC, negatively correlated with the contents of soil organic matter and total N, and had no correlation with the contents of soil total K and total P. The patchy vegetation distribution had potential trends of salinization and degradation.