Thousands more trees to discover!

There are 14% more tree species in the world than we previously thought, according to a new study, authored by an international group of 146 scientists. Amongst these were Simon Lewis and Oliver Phillips, who are based at the University of Leeds.

Using the largest forest database yet assembled, the team suggest that there are roughly 73,000 tree species on Earth. With only around 64,000 species currently known to science, this suggests that there are still about 9000 species yet to be discovered!

To reach their estimate, the team used networks of ecological plots which contained data on the number of trees in each location and the frequency at which different species were found. In particular, the RAINFOR, AfriTRON, and networks are coordinated from the University of Leeds and are located throughout the tropics, together contributing data from millions of individual trees to the research.


Locations and number of different tree species on a world map

The number of tree species and individuals per continent in the Global Forest Biodiversity Initiative database. Depicted here are some of the most frequent species recorded in each continent. Credit: PNAS paper


The study, led by Purdue University in the US, reveals that roughly 40% of undiscovered tree species are in South America and potentially one-third of all tree species not yet discovered may be rare, with very low populations and limited spatial distribution.

These findings highlight the vulnerability of global forest biodiversity to human-made changes in land use and climate, which disproportionately threaten rare species.

Co-author and Professor of Tropical Ecology at Leeds Oliver Phillips, said:

Knowing how many species there are – and especially where diversity and rare species are concentrated – is essential if we are to protect them, the carbon they store, and the myriad other unique plants and creatures sheltered beneath their boughs.

South America is the continent with the highest estimated number of rare tree species (roughly 8,200) and by far the highest number of tree species (at least 31,000).

Professor Phillips added:

With 3,900 tree species yet to be discovered in this one continent, our analysis shows that many are concentrated in endangered hotspots of diversity where the Amazon forest meets the Andes in Peru, Colombia, Ecuador, Venezuela and Bolivia.


This makes forest science and conservation of paramount priority in South America.


This scientific article is free to read online via PNAS