Water and nutrient use efficiencies of Robinia pseudoacacia, Amygdalus davidiana, and Armeniaca sibirica and their potential driving forces in monoculture and mixed stands on the Chinese Loess Plateau

Abstract Aims The effects of mixed plantations, in comparison with corresponding monoculture plantations, on both water and nutrient use efficiencies remain unclear. Methods Robinia pseudoacacia mixed (R. pseudoacacia and Amygdalus davidiana, RPAD; R. pseudoacacia and Armeniaca sibirica, RPAS) and monoculture (R. pseudoacacia, RP; A. davidiana, AD; and A. sibirica, AS) stands on the Loess Plateau were used to determine leaf water (WUE), nitrogen (NUE), and phosphorus (PUE) use efficiencies and their potential driving forces. Results Mixing R. pseudoacacia and A. sibirica is a good strategy to maximize soil nutrient resources. Compared with monocultures of all species, R. pseudoacacia and A. davidiana in RPAD and A. sibirica in RPAS had higher WUE and lower NUE and PUE; P limitation of R. pseudoacacia in either RPAD or RPAS was lower than that in RP. As a whole, a trade-off was observed between WUE and NUE in all species, and between WUE and PUE in A. davidiana and A. sibirica. Moreover, WUE was primarily driven by stand density (SD), crown area (CA), soil total nitrogen (TN), and total phosphorus (TP) for R. pseudoacacia and A. sibirica; SD, CA, and TN for A. davidiana; SD, CA, and TP for A. sibirica. NUE was driven by leaf nitrogen content per mass (Nmass), soil organic carbon (SOC), and TP for R. pseudoacacia and A. sibirica, Nmass and SOC for A. davidiana. Conclusions Although mixed species showed different water and nutrient use efficiencies based on inherent factors and site conditions, the trade-off between WUE and NUE remained unchanged.