The effect of hydraulic and leaf photosynthesis properties on the spread and distribution of Dasiphora fruticosa in Qinghai-Tibet Plateau alpine meadows

Abstract

Abstract Background and Aims Qinghai-Tibet Plateau is the largest alpine grassland area in the world. Alpine region is a typical and unique plateau ecosystem. Natural and human-induced factors have resulted in shrub encroachment in the Qinghai-Tibet Plateau alpine meadows. Yet, the role of functional traits of different plant organs in shrub encroachment remain insufficiently explored. Methods Here, we measured stem and leaf hydraulics, leaf photosynthesis characteristics, and other functional traits of D. fruticosa in different habitats. Results We found that hydraulic traits (KL, KS, π0, ε) and leaf photosynthetic capacity (Aa, Am, gs) were key factors in the shrub encroachment of D. fruticosa. In addition, variations in root average diameter (RAD) and specific root length (SRL) were mainly influenced by soil total nitrogen (STN) and soil total phosphorus (STP) between two habitats. On soil water and nutrient deficient sunny slopes, below-ground functional traits of D. fruticosa tend to favour a resource acquisition strategy to acquire more soil nutrients. On less stressful shady slopes, the above-ground organs of D. fruticosa exhibited higher hydraulic efficiency and photosynthetic capacity, and adopted a resource acquisition strategy. Thus it seems the below- and above-ground functional traits of D. fruticosa in different habitats are coordinated to comprise the whole plant ecological response. Conclusion Our study clearly shows hydraulic functional traits and leaf photosynthesis characteristics play key roles in shrub encroachment. This research also provides new insights for understanding the adaptation strategies of plant functional traits under different habitats.