Estimated number of tropical tree species according to Slik et al. (2015)

Rhett A. Butler

The world's tropical rainforests are likely home to 40,000 to 53,000 tree species, argues a paper published this week in Proceedings of the National Academy of Sciences (PNAS).

Analyzing abundance data spanning 657,000 individual tress across 11,371 species, Ferry Slik of Universiti Brunei Darusallam and 140 other researchers developed estimates for each of the world's three major tropical regions: the Indo-Pacific, the Americas, and continental Africa. They conclude that Asia and the Americas are the most speciose when it comes to trees.

The findings come in at the high end of previous estimates for the tropics, which range from 37,000-50,000. The authors chalk up the differences to their inclusion of dry forests. However unlike previous studies, the new research concludes that Asia is roughly on par with the Americas when it comes to tree diversity.