Fig. 2: Latitudinal gradients in tree beta-diversity.

Total beta-diversity, species turnover, and species nestedness of all trees, AM trees, and EcM trees across latitudes at quadrat scales of 10 m × 10 m (a–c), 20 m × 20 m (d–f), and 50 m × 50 m (g–i). Orange points represent total beta-diversity and its two components (species turnover & nestedness) of all trees and orange lines represent their latitudinal patterns. Green points represent total beta-diversity and its components of AM trees and green lines represent their latitudinal patterns. Blue points represent total beta-diversity and its components of EcM trees and blue lines represent their latitudinal patterns. Points are the mean values and the error bars are the 95% confidence intervals, estimated using the non-parametric bootstrapping method (n = 200). In total, 200 replicates of average pairwise beta-diversity and its components were calculated based on 30, 15, and 15 randomly sampled quadrats of 10 m × 10 m, 20 m × 20 m, and 50 m × 50 m from each forest plot, respectively. Solid lines indicate significant relationships with latitude whereas dashed lines indicate non-significant relationships fitted using the beta regression. The error bands (shaded areas) are the 95% confidence intervals of the fitted relationships, with sample size n = 45 for all trees, n = 44 for AM trees, and n = 43 for EcM trees at the 10 m × 10 m scale; with n = 45 for all trees, n = 44 for AM trees, and n = 44 for EcM trees at the 20 m × 20 m scale; and with n = 41 for all trees, n = 40 for AM trees, and n = 41 for EcM trees at the 50 m × 50 m scale.