Fig. 2.

Estimated botanical diversity of tropical Africa. a Estimated species diversity based on the Chao1 estimator for each 0.5° sampling units (SUs) with more than 100 records. b Effective number of species estimated using the Nielsen statistic per 0.5° SUs with more than 100 records. Dashed lines represent the limits for tropical Africa as defined in our study. This map is based on georeferenced herbarium records, silica gel samples and plot data