Water use and physiological ecological adaptation strategies of Caragana microphylla of different forest ages in hunshandake sandy
摘要
Desertification is a major ecological challenge in China’s arid regions. Caragana microphylla, a dominant sand-fixing shrub in the Hunshandake Desert, faces declining stability as plantations mature. Understanding its water use strategies and physiological adaptations across different forest ages is therefore essential for effective vegetation restoration in sandy ecosystems. Thus, the present study selects three- and eight-year-old C. microphylla plants in the Hunshandake sandy land as research objects. Hydrogen and oxygen stable isotope methods are used to identify plant water sources and calculate water use efficiency, while leaf functional traits (e.g., specific leaf area, C/N/P content) and long-term water use efficiency (via δ13C) were also measured. The results demonstrate that the primary water source for both three- and eight-year-old C. microphylla was 0–20 cm soil layer, and the surface water use efficiency of three-year-old C. microphylla is higher than that of eight-year-old plants. No significant difference is observed in long-term water use efficiency between both age groups. The nitrogen and phosphorus content in the leaves of eight-year-old C. microphylla decrease, while the C/N, C/P, and N/P increase. Therefore, eight-year-old C. microphylla plants maintain their growth needs by improving their nutrient utilization efficiency. The water use efficiency and nutrient use efficiency of C. microphylla exhibit synchronous adaptability. Future studies must consider not only the physiological and ecological adaptation of C. microphylla but also the impact of different restoration years on grassland communities and ecosystem functions.