Abstract: Understanding the responses of the relationships between plant functional diversity and species diversity to the variation of soil water and salinity is beneficial to revealing the mechanisms underlying species coexistence in stressful environment. In this study, we analyzed plant functional diversity, species diversity, and the variation of their relationship under high and low soil water and salinity environment in a desert near Ebinur Lake. We found that: (1) Functional divergence in high soil water and salinity environment was significantly lower than that in low soil water and salinity environment, whereas the pattern of species diversity index (Fish-α) was opposite. (2) Results from both simple and multiple regression analysis showed that species diversity significantly improved functional diversity (RaoQ) and functional richness in conditions with high soil water and salinity, while in low soil water and salinity environment, species diversity improved functional diversity and functional evenness, but suppressed functional divergence. (3) Species diversity had higher predictive power for functional diversity in low soil water and salinity environment. (4) Functional richness, divergence and evenness were more sensitive to the changes of soil water and salinity. Overall, this study provides valuable clues for plant community assembly, recovery and management in desert.

Key words: maize-soybean relay strip intercropping system, reduced N application, N residue, N loss, ammonia volatilization.