|
|
|
| Fractal features of soil aggregate structure under different land use in the Hilly-gully region of Loess Plateau |
| Zhou Ping1,2,Liu Guobin1,3,Hou Xilu1 |
| 1.Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,712100,Yangling,Shaanxi;2.Graduate University of Chinese Academy of Sciences,100049,Beijing;3.Northwest A&F University,712100,Yangling,Shaanxi: China |
|
|
|
|
Abstract The status of soil aggregates,water stable aggregates and microaggregates are important factors affecting soil structures and features.Based on the fractal theory,the fractal dimension of soil aggregates and microaggregates structure under seven different land use types in Zhifang Hilly-gully region was studied.The results showed that: the fractal dimension of the upper layer(0 to 20 cm) soil aggregate structure under these seven land use types ranged from 1.641 to 2.114.The fractal dimension of soil aggregate of artificial meadow was highest,followed by orchard,slope crop-land,arbor forest land,shrub land,natural meadow and artificial terrace.The fractal dimension of water stable soil aggregate ranged from 1.744 to 2.384,the fractal dimension of orchard water stable soil aggregate of artificial meadow was highest,followed by arbor forest land,artificial meadow,slope crop-land,natural meadow,artificial terrace and shrub land.Both of the conditions showed the same law: The lower total amount of the soil aggregates(more than 0.25 mm) was,the higher fractal dimension was.There were remarkable negative correlation between the fractal dimension and not less than 5 mm, 5 to 2 mm and not less than 0.25 mm soil aggregates and water stable aggregates contents.But significant positive correlation with less than 0.25 mm soil aggregates.Considered the rate of soil structural damage,the soil structure and stability of shrub land was the highest,the next was natural meadow,artificial meadow was the lowest among these seven land use types.In the upper soil layer (0 to 20 cm) the range of fractal dimension of soil microaggregate was 2.360 to 2.487.The fractal dimension of soil microaggregate of natural meadow was highest,followed by arbor forest land,slope crop-land,artificial terrace,artificial meadow,orchard,and shrub land was the lowest of that.It was showed that shrub land and natural meadow were beneficial to forming soil microaggregates. The correlation analysis results showed that fractal dimension had remarkable negative correlation with 0.25 to 0.05 mm and more than 0.001 mm microaggregates,also had positive correlation with less than 0.001 mm microaggates.But the soil texture of lower layers(20 to 60 cm) were relevant to the parent material and little affected by human beings activities.There existed significant positive correlation among three fractal dimensions(P<0.05),also had negative correlation between soil organic matter and fractal dimensions(P<0.05).The fractal dimension could be one of the indices of soil quantity evaluation.The fractal theory was also considered as a new tool to research on the soil structure and features.
|
|
Received: 09 May 2007
|
|
|
|
|
|
|
