Different water and photosynthetic resource use strategies explain the widespread distribution of Dasiphora fruticosa in Qinghai-Tibet Plateau alpine meadows

Alpine meadow ecosystems, sensitive to global climate change, are experiencing widespread shrub encroachment, with Dasiphora fruticosa emerging as one of the most prominent encroaching species in this region. Hydraulic and photosynthetic use strategies play crucial role in plant adaptation to climate change. However, it remains unclear how D. fruticosa achieves encroachment by adjusting hydraulic and photosynthetic traits. We examined the hydraulic, leaf, and fine root economic traits of D. fruticosa on shady and sunny slopes with varying soil nutrient levels and degrees of encroachment. Results showed that the hydraulic and photosynthetic traits of D. fruticosa were closely related to its encroachment success. Soil nutrients affects the hydraulic adaptation strategies: soil total phosphorus (STP) significantly increased stem hydraulic conductivity (K_S), while soil total nitrogen (STN) and soil pH decreased the water potential at 50 % loss of K_S (P₅₀). Consequently, D. fruticosa on shady slopes exhibited greater K_S, while those on sunny slopes demonstrated lower P₅₀, indicating trade-off between hydraulic efficiency and safety. Furthermore, D. fruticosa on shady slopes could adjust stomatal conductance (g_s) to avoid embolism, facilitating more severe shrub encroachment.