Fungal partners’ failure to move spells trouble for trees

Trees may find their migration to more suitable climates restricted by the absence of vital passengers crucial to their survival.

As world climates shift amid the increase in global temperatures due to anthropogenic carbon emissions, many plants and animals are moving into more suitable habitats for their growth and protection.

But trees appear to be taking longer to make those shifts.

The reason may be due to the absence of a key ‘life partner’ – special fungal pairs that have evolved symbiotic relationships with the root systems of trees.

These mycorrhizal fungi exist below the surface and attach themselves to roots, creating an extensive below-ground network that supports nutrient uptake and gas exchange for the tree.

But those relationships are at risk amid climate-forced migrations, according to new research published in the Proceedings of the National Academy of Sciences.

In it, researchers affiliated with the Society for the Protection of Underground Networks say about 35% of tree-fungi partnerships will be hindered in future climate change scenarios.

This analysis looked at 50 North American tree species and 400 ectomycorrhizal fungi, identifying that trees are likely to shift to higher latitudes (towards the poles) as local climates get warmer.

But ‘mismatches’ between trees and some suitable mycorrhizal partners will also occur – among the third of compromised partnerships, pine species appear to be the most impacted.

It also explains why some trees are not migrating further north, with the lack of suitable fungi partners making it harder for species to thrive in new areas.

“Ectomycorrhizal fungi have a different relationship to climate than ectomycorrhizal trees do,” says Clara Qin, a data scientist at the Society for the Protection of Underground Networks.

“We are finding evidence that the trees have to answer for these differences.

 “While we expect climate-driven migrations to be limited by [non-living] factors like the availability of space at higher latitudes and elevations, we don’t usually account for biotic limitations like the availability of symbiotic partners.”

Qin’s research group describes the tree-fungus challenge of the future as one where winners and losers will be created by climate change and calls for this relationship to be considered when developing assisted migration strategies for North American species.

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