How many tree species are there in the world?

In 2017, the Botanic Gardens Conservation International (BGCI), a global network made up of many botanic gardens, published the first-ever count of the number of individual tree species that exist across the entire world. After over two years of work, which involved consulting with many experts and using hundreds of published sources, they came to the conclusion that exactly 60,065 different species currently exist across the globe. The main reason behind compiling and documenting this was to assist people in trying to conserve the world’s tree diversity – highlighting how many of the world’s trees were threatened with extinction would allow conservation efforts to be targeted in specific areas.

Many of the world’s species were found to inhabit hot and tropical climate zones – for instance, 9,000 different tree species were found to be native to Brazil, with around 5,700 species found in Colombia and just over 5,000 in Indonesia. Furthermore, Malaysia, Venezuela and China each contained thousands of native species. Apart from extreme polar areas, tree species were found to inhabit pretty much every single climatic zone – even in some arid areas. In order to adapt to these climate zones, individual tree species can be very different from one another, demonstrating that a great level of diversity exists within tree types.

20% of tree species are under threat of extinction.

However, the BGCI also uncovered a rather worrying statistic – that almost a fifth of the world’s tree species are currently threatened with extinction. With rapid deforestation underway, particularly in countries with vast tropical rainforests, this is unfortunately not surprising. The deforestation of the Amazon rainforest, which hosts almost a sixth of the world’s species, is putting many tree species at risk. However, not just species in tropical biomes are under threat – climate change is negatively impacting tree types in other parts of the world, by making the growing conditions increasingly difficult for certain species in their native habitat. This is very worrying, especially as extinction threatens the biodiversity of tree species, with subsequent impacts on the rest of their ecosystem.

Biodiversity is essential for healthy ecosystems.

The larger the range of different tree species, the greater the biodiversity of the associated ecosystem. Although some animal species can adapt very well to different environments, with the ability to use a wide range of tree types for food and shelter, other species depend on only certain tree species and habitats. Also, many habitats worldwide have a specific and unique ecosystem that depends largely on the presence of a certain mixture – or diversity – of different tree species. These include (but are not limited to) the temperate rainforests of the Pacific Northwest, the vast sub-polar boreal forests of the Northern Hemisphere, and Mangrove swamps in tropical regions. Each habitat has a specific set of animal species that depend on certain trees, mainly for food and shelter. Reducing the number of tree species would subsequently reduce the biodiversity of many ecosystems.