14% more species of trees on Earth than previously thought

New research has revealed the number of different types of trees is significantly higher than estimates once suggested, with over 9,000 yet to be discovered.

The study involved more than 100 scientists from countries across the globe, and the largest forest database ever created. Those involved in the project used occurrence data from two sets – the Global Forest Biodiversity Initiative, and TREECHANGE – both of which use ground-sourced forest-plot information. 

Combined, those datasets showed a total of 64,100 documented tree species worldwide. Novel methods, based on Alan Turing’s work to crack the Nazi enigma code in World War II, were then used to estimate the total number of unique tree species at biome (i.e. savanna, rainforests, boreal forests) continental, and global scales. Based on this calculation, researchers believe there could actually be 73,274 types of trees, 9,200 of which are still to be discovered.

Around 40% of are expected to be in South America, specifically the Amazon basin and high altitude Andean forests. This is partly because the continent is already home to 27,000 tree species, more than any other continent, with the highest estimated rate of endemic tree species (49%) and more rare types of trees than anywhere else in the world. 

‘These results highlight the vulnerability of global forest biodiversity to anthropogenic changes, particularly land use and climate, because the survival of rare taxa is disproportionately threatened by these pressures,’ said University of Michigan forest ecologist Peter Reich, one of two senior authors of the study’s paper which was published in Proceedings of the National Academy of Sciences.

‘By establishing a quantitative benchmark, this study could contribute to tree and forest conservation efforts and the future discovery of new trees and associated species in certain parts of the world,’ he continued. ‘This makes forest conservation of paramount priority in South America, especially considering the current tropical forest crisis from anthropogenic impacts such as deforestation, fires and climate change.’

In related news, last year scientists discovered that mature oak trees increase their rate of photosynthesis in response to rising CO2 levels in the atmosphere. 

Image credit: Tobias Tullius