Fig. 4 The best-fit SEMs showing the influences of site-level native plant performance (Pnative_site ), site-level native plant richness (Rnative_site ), annual mean temperature (T ), water nutrient status (Nwater ), average water depth (Hsite ), habitat size (Ahabitat ) and distance to the nearest town (Lsite-town ) on site-level mean biomass of exotic plants (A), and the influences of quadrat-level native plant performance (Pnative_quadrat ), quadrat-level native plant richness (Rnative_quadrat ), quadrat-level co-occurring exotic plant performance (Pexotic_quadrat ), T ,Nwater , and water depth (Hquadrat ) on quadrat-level population biomass ofA. philoxeroides (B), E. crassipes (C), and C. caroliniana (D). Arrow widths are proportional to standardized path coefficients (values are also given, *P < 0.05, **P < 0.01, *** P < 0.001), and R2values are given for each endogenous variable.