The biodiversity of the American tropics is remarkable, and Amazonia biome is home to an estimated 16,000 species of trees, of which as many as half may have populations of less than 1,000 individuals. However, how these rare and possibly endangered species are distributed, is unclear.
Using more than 100 million GBIF-mediated occurrences of all angiosperm species, researchers (headed by the second prize winner of the 2016 Ebbe Nielsen Challenge) identified potentially rare species in the Neotropics and characterized their distributions. Within Amazonia they find 10,000 rare species, whereas the surrounding Neotropics account for 20,000 rare species. In both case, the species are widely scattered but with concentrated centres in montane regions.
Comparing the findings to a vegetation plot dataset, the researchers find a high level of concordance, suggesting the validity of the approach, although acknowledging a potential of false positives due to sampling gaps and biases.