Beta diversity across scales
Overall, turnover (Multisite βSIM) was lower at the archipelago scale (large, 0.25) than within islands and within habitats within islands (intermediate and small scale respectively, fig. 2).
Regarding the within islands scale, multisite βSIMvalues ranged from 0.7 in Flores to 0.94 in São Miguel (mean = 0.82) (fig. 2). Moreover, 95% confidence intervals from the standardization with 20 cells indicated that São Miguel had the highest turnover, being significantly different from the rest of the islands except Terceira (fig. 3A). Flores was the island with the lowest turnover, but it was also not significantly different from any other island except São Miguel. Turnover calculated between pairs of islands (Pairwise βSIM) was very low and ranged from 0.06 between Faial and São Jorge, to 0.17 between São Miguel and São Jorge (mean = 0.11) (fig. 2), supporting the results obtained with Multisite βSIM at large scale.
Turnover (Multisite βSIM) within habitats showed very contrasting patterns. In native forests, the turnover value in Terceira was twice the value as in Flores (0.81, and 0.41 respectively; fig. 2 and fig. 3B), and the 95% confidence intervals from the standardization at 20 cells indicated that this difference was significant (fig. 3B). For naturalized vegetation, strong variations between islands were also found with turnover values ranging from 0.86 for São Miguel to 0.23 for Pico. Thus, the 95% confidence intervals from the standardization at 20 cells indicated that βSIM of São Miguel was significantly higher than βSIMof Pico and São Jorge (fig 3B). In contrast, turnover values for seminatural pastures were consistently high across all islands being 0.90 for São Miguel and São Jorge (fig. 3B). Interestingly, as in the case of between pairs of islands, turnover between pairs of habitats (Pairwise βSIM) was found to be very low within islands, as all βSIM values were lower than 0.3 (fig. 2).