<p>(A) Comparison of species richness by site. Color code: yellow = 1896–1950, green = 1950–2013. A paired t-test indicates this is a significant increase in richness when considering all sites (t = 2.215, p = 0.039). (B) Degree of similarity between each pair of sites in the historical and modern records, using the Sorensen Index. Size of filled circles indicates degree of similarity for each pair (See Table S3 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093092#pone.0093092.s009" target="_blank">File S1</a> for exact values). Comparisons of circles in different time periods show an increase in similarity for each site pair, thus a decrease in beta-diversity (Table S4 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0093092#pone.0093092.s009" target="_blank">File S1</a>). Wilcoxon signed-rank test: p<0.0001.</p
