FOS researcher’s work mapping Earth’s hidden tree-microbe network published in Nature

Summarised by Dr. Fairuzeta Ja’afar


The paper, “Climatic controls of decomposition drive the global biogeography of forest-tree symbioses,” published in Nature, showcased research undertaken by the Botanic Gardens Conservation International (BGCI) consortium, which includes Associate Professor Dr Ferry Slik from the Environmental and Life Sciences Programme.

There is a network of fungi and bacteria that is in a symbiotic relationship with the tree roots of forest trees. These microbes determine the trees’ ability to access nutrients, act as a carbon sink and withstand the effects of climate change. Characterising and identifying the factors that affect the global distribution of these microbes leads to a better understanding of the present situation and can assist in making predictions regarding the future functions of forest ecosystems.

For the first time ever, researchers have mapped this underground network of microbes connecting forest trees around the world using an enormous data set of more than 1.1 million forest plots. These plots collectively contain information on more than 30 million individual trees and 28,000 tree species from more than 70 countries. This information came from forest scientists around the world, nearly 200 of whom then contributed ground-sourced forest measurements from their study areas. The 2015 study estimated there were about 3 trillion trees on Earth.

Map shows the distribution of trees likely to associate with arbuscular mycorrhizal fungi. Image by Brian Steidinger.

Map shows the distribution of trees likely to associate with ectomycorrhizal fungi. Image by Brian Steidinger.

In order to handle this huge dataset, machine learning was used for different tree-microbe associations correlated with various environmental factors, such as temperature, rainfall, soil chemistry and topography. Using machine learning algorithms, the importance of all the variables in the data were calculated, from the highest to the lowest, to predict the distribution of tree-microbe associations, filling in spatial gaps where data on trees and microbes are poor or unavailable.

The new maps confirm patterns that have long been suspected. For example, arbuscular mycorrhizal fungi dominate forests in the warmer tropics while ectomycorrhizal fungi are more widespread in colder boreal and temperate forests.

Full paper:

Steidinger, B.S., Crowther, T.W., Liang, J. et al. Climatic controls of decomposition drive the global biogeography of forest-tree symbioses.
Nature 569, 404–408 (2019) doi:10.1038/s41586-019-1128-0
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