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| Soil particles and fractal features in a typical watershed of the middle reach of the Dan River |
(1.Key Laboratory of Northwest Water Resources and Environment Ecology of Ministry of Education; Xi’an University of Technology, 710048,
Xi’ an, China; 2. State Key Laboratory of Soil Erosion and Dry-land Farming on the Loess Plateau, Institute of Soil and Water Conservation,
Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi, China) |
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Abstract 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 100m×100m 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 10-40cm 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 10-20cm 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 0-20cm （P<0.01). Both fractal dimension and soil total nitrogen contents were positively related to the contents of silt and clay at the 20-60cm depth （P<0.01). The storage of silt and clay in the studied area in the 0-10cm layer was 132800t. The contents of silt and clay per square meter in the 0-10cm soil layer in the cropland, forestland and grassland were 74.71, 71.54 and 70.23kg/m2, respectively.
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Received: 27 November 2012
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