丹江中游典型小流域土壤颗粒及分形特征

在丹江鹦鹉沟小流域，利用网格状取样和典型样地取样相结合的方法，进行土样采集，共计采样点268个，研究土壤颗粒组成和分形特征，以及与土壤全氮之间的相互关系。结果表明：土壤粉黏粒质量分数随土壤深度的增加而增大，不同土层下土壤粉黏粒质量分数平均值均表现为农地〉林地〉草地。经ANOVA分析，不同土地利用在10—40cm土层的粉黏粒质量分数存在显著差异（P〈0．05）。不同植被类型间土壤颗粒分形维数亦存在显著差异（P〈0．05），10～20cm土层的土壤颗粒分形维数更能代表不同土地利用的差异。土壤颗粒分形维数与坡度呈显著负相关（P〈0．05），与坡向和海拔无显著相关性。土壤全氮质量分数在0～20cm土层与中粗砂粒质量分数呈极显著正相关（P〈0．01），土壤颗粒分形维数和土壤全氮质量分数在20～60cm土层均与土壤粉黏粒质量分数呈极显著正相关（P〈0．01）。鹦鹉沟流域0～10cm土层的土壤粉黏粒储量为13．28万t，不同土地利用下0～10cm土层每m2土壤粉黏粒储量表现为农地〉林地〉草地，分别为74．71kg／m2、71．54kg／m2和70．23kg／m2。

Soil particles and fractal features in a typical watershed of the middle reach of the Dan River

The objectives of this study were to explore soil particle size distribution and fractal features, as well as the relationship between fractal dimension and soil total nitrogen in the Yingwugou Watershed, which is sited in the middle reach of the Dan River. Soil samples were collected based on a 100 m x 100 m grid system and typical sample plots. A total of 268 sites were sampled. The results indicated that the contents of silt and clay in the soil profile increased as the soil depth increased, and the mean contents of silt and clay in different soil horizons were in the order of cropland 〉 forestland 〉 grassland. The ANOVA showed that there were significant differences in the contents of silt and clay in a depth range of 10- 40 cm for different land use types （P 〈 0.05）. The fractal dimensions of soil particle size distribution among different plant communities also showed significant differences （P 〈0.05）. However, the fractal dimension of particle size distribution in the l0 - 20 cm layer could better represent the differences of varied land use types. There was a significant correlation between fractal dimension of particle size distribution and slope （P 〈 0.05 ）, but not with elevation and aspect. A significant correlation was observed between soil total nitrogen contents and coarse sand at a depth range of 0 -20 cm （P 〈 0.01 ）. Both fractal dimension and soil total nitrogen contents were positively related to the contents of silt and clay at the 20 -60 cm depth （P 〈0.01）. The storage of silt and clay in the studied area in the 0 - 10 cm layer was 132 800 t. The contents of silt and clay per square meter in the 0 - 10 cm soil layer in the cropland, forestland and grassland were 74.71, 71.54 and 70.23 kg/m/, respectively.