Abstract: Revealing the relationship between vegetation distribution in drainage ditches and soil factors can provide theoretical basis and technical guidance for restoring eco-environment of ditch wetlands and construction of ecological irrigation areas in arid environment. With a case study on the main and sub-main drainage ditches of a saline area in Lubotan reclamation area at Fuping of Shaanxi Province, we examined spatial and temporal distribution of vegetation, as well as soil water content, electrical conductivity (EC) and pH on side slope of drainage ditches, and the correlation between vegetation and soil properties based on field investigation, variance analysis, correlation analysis, typical correlation analysis and RDA analysis. The results showed that: (1) Vegetation on the side slope of the drainage ditches displayed obvious zoning pattern, including a reed area, transition area, and a symbiosis area. The species in main ditches were more diverse than that in the sub-main ditches, whereas species dominance was lower than that in the sub-main ditches. The Simpson dominance index decreased with the distance from drai-nage ditches in different areas of main ditches and sub-main ditches, while species richness index, Shannon diversity index and Pielou evenness index increased with the distance from drainage ditches. (2) Soil moisture was the highest in March (23.7% on average), and soil EC and pH were the highest in September (with a mean value of 576.97 μS·cm^-1 and 8.95, respectively), with no significant differences among different time periods. Soil moisture, EC, and pH of reed area in main ditches were the highest. Soil water content of reed area in sub-main ditches was the highest, while soil EC and pH in the transition area were the highest, with significant differences among different areas. (3) Soil moisture and EC were the key factors driving the spatial distribution and plant species richness in drainage ditches in the arid region. Based on those findings, we put forward artificial intervention methods and measures of controlling drainage and laying prefabricated vegetation blanket to regulate vegetation succession and vegetation construction in ecological drainage ditches in arid regions. Our results may provide scientific basis for the construction of ecological irrigation area.

Key words: drainage ditch, arid area, vegetation spatial distribution, soil factor.