An international research team with the participation of Polish scientists Prof. Bogdan Jaroszewicz, head of the Białowieża Geobotanical Station of the University of Warsaw, Prof.  Tomasz Zawiła-Niedźwiecki, director of the Center for Coordination of Environmental Projects in the State Forests, Dr Eng. Krzysztof Jan Stereńczak from the Forest Research Institute and Prof. Andrzej M. Jagodziński from the Institute of Dendrology of the Polish Academy of Sciences estimated the number of tree species on Earth in total and by continents.

To answer the question, scientists used data on the geographic distribution of 38 million trees, which grew on over 100,000 research plots on all continents, where woody plants grow.

Prof. Bogdan Jaroszewicz emphasized that the database allowed scientists to estimate the potential number of tree species on Earth and continents. As a result of the statistical analysis, the scientists estimated the number of tree species on Earth at 73.3 thousand, while the list of tree species prepared on the basis of the available literature contained 64.1 thousand woody plants. This means that over 9,000 tree species in the world are still not discovered nor described.

In terms of continents, South America is characterized by the highest number of tree species (approximately 43% of the total number of tree species). According to estimates by scientists, in some regions of South America, the number of tree species per hectare of forest may reach 200, which is at least four times more than the number of native tree species in Poland. The species richness of trees in other continents is much lower and more even: Eurasia – 22%, Africa – 16%, North America – 15%, Oceania – 11% of the estimated number of species.

The results of the scientists’ research were published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Adrian Andrzejewski