Abstract: Microtopography can change the water-salt distribution pattern and plant growth in coastal saline-alkali soils, and thus realize the efficient utilization and sustainable development of coastal saline-alkali lands. Using the method of sampling lines, we investigated soil water content, soil electric conductivity, and plant biomass at different elevations along the slope of coastal saline-alkali land, and analyzed the factors influencing plant biomass and root-shoot ratio. The results showed that elevation significantly affected soil water content, soil electric conductivity, and pH. Water content and pH across various soil layers tended to decrease with increasing elevation, while soil electric conductivity of topsoil tended to increase. The profile distribution of soil salinity showed a phenomenon of “surface accumulation”, while soil water showed a trend of “bottom layer”. Suaeda salsa and Phragmites australis were the dominant species on the saline slopes. Aboveground biomass per individual plant of both species positively correlated with soil electric conductivity and negatively correlated with soil pH. As the elevation increased, belowground biomass and root/shoot ratio showed a downward trend, while aboveground biomass showed an upward trend. Soil water content and pH together accounted for 68% of the variation of rootshoot ratio. Therefore, ecological restoration and high-efficiency utilization model in coastal saline-alkali land based on microtopography breaks through the traditional concept of saline-alkali land management and utilization, and help realize high-efficient and comprehensive utilization of coastal saline-alkali land.

Key words: coastal saline-alkali land, microtopography, elevation, soil water and salinity, biomass, rootshoot ratio.