Enclosure Affects Soil Preferential Flow Process by Adjusting Root-soil
Structure
Abstract
Preferential flow plays an important role in the ecosystem. In order to
understand the influence of enclosure on the root-soil structure in the
preferential flow region, and to understand the difference of root-soil
structure between the preferential flow region and the matrix flow
region. In this paper, the soil in the preferential flow region of
Caragana korshinskii shrub under enclosure or grazing measures in
Yanchi, Ningxia, China was selected as the research object. The
geometric distribution and topological indexes of root-soil structure
(aggregates, macropores and roots) were obtained by CT scanning and
three-dimensional image processing. The results showed that the enclosed
natural grassland had the highest staining area ratio (40.38%) and
staining depth (271 mm). The distribution of soil aggregates and
macropores in grazing artificial C. korshinskii shrub and
enclosed natural C. korshinskii shrub was more uniform. Enclosure
significantly reduced the number density and volume density of soil
aggregates, macropores and roots in the preferential flow region
(p<0.05). Compared with the matrix flow region, the number
density of soil aggregates in the preferential flow region increased
significantly (p<0.05), and the average equivalent diameter
decreased significantly (p<0.05). Enclosure negatively affects
soil aggregates and macropores. Aggregates directly promote the
preferential flow process, and macropores indirectly affect the
preferential flow process through aggregates. Clarifying the
relationship between enclosure, root-soil structure and preferential
flow can provide a basis for vegetation restoration management in arid
and semi-arid areas.