Climate mismatches with mycorrhizal fungi slow forest range shifts

Climate mismatches with ectomycorrhizal fungi contribute to migration lag in North American tree range shifts.

Take-home: Trees can’t move north without their underground fungal partners (forests are stuck because fungi aren’t migrating fast enough).

North American trees are not keeping pace with climate change because their fungal partners aren’t moving with them. Trees depend on ectomycorrhizal fungi for survival, but climate mismatches mean the fungi often aren’t present in newly suitable areas. This slows forest migration and highlights the need to consider both trees and fungi in conservation planning.

As the climate warms, many North American trees are expected to move northward to cooler areas. But in reality, their migrations are happening much more slowly. This study shows that one reason is the trees’ underground partners—ectomycorrhizal fungi.These fungi help trees get nutrients and survive, but their own ranges don’t always shift in step with the trees. That means when trees arrive in new areas, the right fungi may not be there to support them. This “climate mismatch” between trees and fungi helps explain why forests are lagging behind climate change and suggests that protecting both trees and their fungal partners is crucial for future forest health.

Our study explores why many North American trees are not shifting their ranges northward as quickly as expected in response to climate change. We investigate whether ectomycorrhizal (ECM) fungi (symbiotic fungi essential for tree nutrient uptake) play a role in this migration lag. By analyzing large-scale datasets on tree and fungal distributions, the researchers found that suitable climates for trees are moving north faster than those for their ECM fungal partners. This creates climate mismatches, where trees may reach new areas but fail to thrive due to a lack of compatible fungi. Our results suggest that tree range shifts are constrained not only by seed dispersal and climate conditions but also by the geography of their fungal partners. The study highlights the importance of including belowground biodiversity in predictions of species’ responses to climate change and in designing conservation strategies.