VIEW LARGER Ectomycorrhizal fungi (the mushrooms connected to the roots of the tree) increase the uptake of nitrogen by the plant, even when that nutrient is scarce in soils. Arbuscular mycorrhizal fungi (associated with the grass roots on the left) do not provide that advantage to their host. By Melissa Sevigny, Arizona Science Desk
Climate change scientists know that plants can’t grow larger with extra carbon dioxide unless they also have nitrogen. But a new study coauthored by a Flagstaff ecologist shows fungus can help plants get around that limitation.
The study appears in this month’s journal Science. It reviews more than 80 experiments measuring plant responses to increased CO2.
Bruce Hungate, director of the Center for Ecosystem Science and Society at Northern Arizona University, is one of the coauthors. He was surprised to find a symbiotic relationship between plants and a certain fungus boosted growth even without nitrogen.
“So it turns out ectomycorrhizal fungi are really good at extracting nitrogen from soil,” Hungate said. “And that is what makes those plants able to respond to high CO2 even if they don’t have extra nitrogen supplied from another source, because the fungus helps do the work for them.”
Ectomycorrhizal fungi are found in forests worldwide. Hungate said adding them to computer models could give more accurate predictions for the speed of climate change. Current models estimate global ecosystems soak up about a quarter of human CO2 emissions.
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