Abstract: Groundwater depth is a critical factor influencing plant survival in deserts. However, our understanding of how plants regulate leaf functional traits in response to variations in groundwater depth remains limited. We investigated leaf functional traits of Tamarix ramosissima at the Daliyaboyi oasis, located in the hinterland of the Taklamakan Desert. We analyzed stable carbon isotope composition (δ¹³C), leaf water content (LWC), specific leaf area (SLA), leaf organic carbon content (LOC), leaf total nitrogen content (LTN), leaf total phosphorus content (LTP), non-structural carbohydrate content (NSC), as well as soil organic carbon content (SOC), soil total nitrogen content (STN), soil total phosphorus content (STP) under three groundwater depths (1.0, 3.4, and 5.0 m). The aim was to explore how leaf functional traits of T. ramosissima vary within an arid desert environment. The results showed that the δ¹³C values and LWC showed no differences across varying groundwater depths. Soil pH values were significantly lower at medium groundwater depth compared to both shallow and deep groundwater depths, while STN was notably lower at shallow groundwater depth than at medium depth. There was a significant positive relationship between LTP and LTN. Furthermore, both LTN and LTP were positively correlated with soil pH. Additionally, soil water content had a significant effect on δ¹³C, SLA, leaf soluble sugar (LSSC), and the ratio of LSSC to leaf starch. Our results indicate that T. ramosissima responds to variations in groundwater depth by adjusting SLA, LTN, LTP, and LSSC. Leaf traits are correlated with soil water content, pH levels, soil organic carbon (SOC), and STN, suggesting that the adaptation of T. ramosissima to the desert hinterland environment is comprehensively influenced by soil water and nutrient availability. These findings provide scientific data and a theoretical foundation for a deeper understanding of the adaptive mechanisms employed by desert plants.

Key words: Taklamakan Desert, groundwater depth, leaf functional trait, soil water content