Ecological Adaptation Strategies of Different Dominant Plants in Typical Arid Regions Based on Water-Photosynthesis Synergistic Relationships

Clarifying how arid zone plants adapt is fundamental for developing targeted strategies for water resource and ecosystem management, However, researches on the synergistic relationships between water sources and photosynthetic characteristics in different plant life forms remain unclear. we quantitatively analyzed the water sources and photosynthetic characteristics of dominant plants in arid regions of Northwest China using stable isotope tracing and a Li-6800 portable photosynthesis system. The results showed that: 1) distinct water use strategies existed among the dominant plants, showing that Populus euphratica primarily used deep soil water (80–100 cm), Tamarix ramosissima opportunistically utilized mid-to-deep soil water (20–80 cm), and Phragmites australis predominantly absorbed shallow soil water (0–20 cm). 2) The photosynthetic characteristics varied significantly across the dominant plant species studied, with net photosynthetic rate ( P n ), transpiration rate ( E ), and stomatal conductance ( g s ) following P. euphratica > T. ramosissima > P. australis , whereas water use efficiency ( WUE t ) ranked T. ramosissima > P. euphratica > P. australis . 3) Different ecological adaptation strategies were associated with distinct synergistic relationships. P. euphratica utilized deep soil water to sustain high E , T. ramosissima employed mid-to-deep soil water with high WUE t , and P. australis used shallow soil water to enhance population dynamics. These results can provide a reference for the water-photosynthesis synergistic relationships of different dominant plants and the optimization of water management and ecological strategies in arid zones.