Though past research has focused on seedlings, these findings give new insight into the value of fungal networks to older trees—which are more environmentally beneficial for functions like capturing carbon and stabilizing soil erosion.
“Large trees make up the bulk of the forest, so they drive what the forest is doing,” said researcher Joseph Birch, who led the study for his PhD thesis in the Faculty of Agricultural, Life & Environmental Sciences.
When they colonize the roots of a tree, fungal networks act as a sort of highway, allowing water, nutrients and even the compounds that send defence signals against insect attacks to flow back and forth among the trees.
The network also helps nutrients flow to resource-limited trees “like family units that support one another in times of stress,” Birch noted.
Cores taken from 350 Douglas firs in British Columbia showed that annual tree ring growth was related to the extent of fungal connections a tree had with other trees. “They had much higher growth than trees that had only a few connections.”