天山中部天山云杉林土壤团聚体分形特征对地形因素的响应研究

Study on the Response of Fractal Characteristics of Soil Aggregates to Topographic Factors in Piceas chrenkiana Forest in Central Tianshan Mountains

采用干筛和湿筛法测定天山中部新疆农业大学天格尔校区不同地形条件(坡度、坡位、坡向、海拔)下天山云杉(Picea schrenkiana var.tianschanica)林土壤团聚体粒径质量分布,通过方差分析和相关分析研究不同地形对土壤粒径分形特征的影响并探讨分形维数与粒级分布的关系。结果表明,不同地形条件下,机械稳定性团聚体在2~0.5 mm颗粒含量最高,介于35.26%~46.61%,均值为39.54%;水稳定性团聚体在0.25~0.053 mm颗粒含量最高,介于20.58%~47.48%,均值为33.56%。不同地形条件下天山云杉林土壤机械稳定性团聚体分形维数为1.036~1.595,水稳定性团聚体分形维数为1.615~2.483。相关回归分析表明,机械稳定性土壤颗粒分形维数仅与0.25~0.053 mm粒径含量的相关性达到极显著水平(P<0.01),水稳定性土壤颗粒分形维数与2~0.5 mm、0.25~0.053 mm颗粒含量的相关性达到极显著水平(P<0.01),说明该研究区域内土壤分形维数主要由2~0.5 mm和0.25~0.053 mm粒径决定,其中0.25~0.053 mm粒径含量是影响该区域土壤粒径非均匀分布及分形维数值变化的主要因素。

Dry and wet sieve methods were used to determine the particle size mass distribution of soil aggregates in Picea schrenkiana forests under different topographic conditions(slope,slope position,slope direction and elevation)in the Tianger Campus of Xinjiang Agricultural University,to study the influence of different topographies on the fractal characteristics of soil particles by analysis of variance(ANOVA)and correlation(COV)and to explore the relationship between fractal dimensions and the distribution of particle sizes.The results showed that,under different topographic conditions,the highest content of mechanically stable aggregates was found in particles of 2-0.5 mm,ranging from 35.26%to 46.61%,with a mean value of 39.54%;and the highest content of water-stable aggregates was found in particles of 0.25-0.053 mm,ranging from 20.58%to 47.48%,with a mean value of 33.56%.The fractal dimension of mechanically stable aggregates in Picea schrenkiana forest soil under different topographic conditions ranged from 1.036 to 1.595,and that of water-stable aggregates ranged from 1.615 to 2.483.Correlation regression analyses showed that the correlation between the fractal dimension of mechanically stable soil particles and the content of particles with sizes of 0.25-0.053 mm only reached a highly significant level(P<0.01),and that the correlation between the fractal dimension and the content of particles with sizes of 2-0.053 mm in water-stable soil particles reached a highly significant level(P<0.01).The correlation between fractal dimension and the content of 2-0.5 mm and 0.25-0.053 mm particles was highly significant(P<0.01),indicating that the fractal dimension of the soil in the study area was mainly determined by the clay particles of 2-0.5 mm and 0.25-0.053 mm,in which the content of clay particles of 0.25-0.053 mm was the main factor influencing the non-uniform distribution of the soil particles in the area and the main factor in the variation of fractal dimension values.