Effects of the biotic and abiotic factors on the overall invasion extent of exotic aquatic plants
Regression models showed that the site-level mean biomass of exotic plants (MBSE ) decreased with increased native plant richness (Rnative_site , P < 0.001), native plant performance (Pnative_site , P < 0.001), and habitat size (Ahabitat , P < 0.05), but increased as water nutrient status (Nwater , P < 0.001) and mean water depth (Hsite , P < 0.05) increased (Fig. 2A-E). The best-fit SEM showed that Pnative_site had a direct effect on MBSE , butHsite and Ahabitat had indirect effects by influencing Rnative_site positively or negatively; Rnative_site andNwater not only had direct effects onMBSE , but also had indirect effects by positively influencing the Pnative_site or negatively influencing the Rnative_site andPnative_site (Fig. 4A). In addition, although there were no significant relationships between theMBSE and annual mean temperature (T , P > 0.05) and distance to town (Lsite-town , P > 0.05), T andLsite-town could affectMBSE by negatively influencing theRnative_site and Nwater (Fig. 2F and G, Fig. 4A). Hierarchical partitioning results indicated that Pnative_site was the most important determinant factor for MBSE (independent effect = 54.55%), followed by Rnative_site ,Nwater , Hsite , T ,Ahabitat , and Lsite-town(independent effects were 25.84%, 13.47%, 3.67%, 1.26%, 1.09%, and 0.12%) (Fig. 5A).