Abstract:

In this study, three typical sand-fixing plants in the desert-oasis transition zone were used as the research objects. To simulate water infiltration of 10 L, 15 L, and 20 L, respectively (simulating light rain, moderate rain, and heavy rain), the field staining tracer method and computer image processing technology were used. The distribution rules and characteristic parameters of the priority flow in the vertical and horizontal sections of the dyed images were analyzed, and the characteristic parameters were selected as evaluation indexes. The mean square decision method was used to determine the degree of development of the soil priority flow in the root zone of typical sand-fixation plants, which provided a reference for the restoration of sand-fixation vegetation and effective utilization of water resources in the desert-oasis transition zone. The results showed that (1) Soil preferential flow occurred in the root zone of sand-fixing plants in the desert-oasis transition zone, and the main types were funnel flow and finger flow. When infiltration water water was increased, the preferential flow occurred laterally. (2) Under the various conditions of water infiltration, the soil staining area ratio in the root zone of the three sand-fixing plants showed a nonlinear decrease with an increase in soil depth. The curve of the soil staining area ratio in the root zone of Haloxylon sacralis and Jujube sacralis showed an “S” shape, and the water infiltration was non-uniform. (3) The priority flow evaluation index P_FI was from large to small: Haloxell (0.685), Sphaerophora sphaerophora (0.543), and Hippophora hippophobia (0.502). The degree of priority flow development of the soil in the root zone was the highest.

Key words: desert-oasis transition zone, soil priority flow, sand-fixing plants, staining tracer test