Trait-based adaptability of Phragmites australis to the effects of soil water and salinity in the Yellow River Delta

Phragmites australis is the dominant species in the Yellow River Delta and plays an important role in wetland ecosystems. In order to evaluate the relationship between phenotypic variation and environmental factors, explore how functional traits respond to changes in electrical conductivity and soil water content, and reveal the ecological strategies of P. australis, we investigated the ecological responses of P. australis to soil properties based on 96 plots along the coastal-inland regions in the Yellow River Delta of China. Within the range of soil water content (SWC, 9.39%-36.92%) and electrical conductivity (EC, 0.14-13.29 ms/cm), the results showed that (a) the effects of salinity were more important than the soil water content for the characterization of the morphological traits and that plant functional traits including leaf traits and stem traits responded more strongly to soil salinity than soil water content; (b) compared with morphological traits such as average height and internode number, physiological traits such as SPAD value, as well as morphological traits closely related to physiological traits such as specific leaf area and leaf thickness, showed stronger stability in response to soil water and salinity; and (c) under the condition of high electrical conductivity, P. australis improved its water acquisition ability by increasing indicators such as leaf water content and leaf thickness. In addition, with the increase in plant tolerance to stress, more resources were used to resist external stress, and the survival strategy was inclined toward the stress tolerator (S) strategy. Under low EC conditions, P. australis increased specific leaf area and leaf area for its growth in order to obtain resources rapidly, while its survival strategy gradually moved toward the competitor (C) strategy.

Automated summary

Phragmites australis shows a stronger adaptability to soil salinity, with plant functional traits responding more strongly to soil salinity than soil water content. Under high electrical conductivity conditions, P. australis enhances water acquisition ability by increasing indicators such as leaf water content and leaf thickness.