Are forest fungi symbiotic?

Symbiotic relationships between trees and the mycorrhyzae that grow in their roots may not be as mutually beneficial as previously thought. Recent experiments had brought into a question a long-held theory of biology: that the fungi or mycorrhizae that grow on tree roots work with trees in a symbiotic relationship that is beneficial for both the fungi and the trees, providing needed nutrients to both parties. But in contrast to the current paradigm, the new research shows that they may be the cause rather than the cure for the nutrient scarcity.

A new study, led by IIASA Ecosystems Services and Management researcher Oskar Franklin in collaboration with the Swedish University of Agricultural Sciences, used a theoretical model to explain the new experimental findings, by simulating the interaction between individual fungus and plant. It suggests that since each organism competes with others in trading nutrients such as carbon and nitrogen, the system as a whole may function more like a capitalistic market economy than a cooperative symbiotic relationship. The competition among trees makes them export excessive amounts of carbon to the fungi, which seize a lot of soil nutrients.

Understanding boreal forest nutrient cycles is incredibly important for modeling climate change, because it influences how much carbon dioxide these regions can absorb, as well as how they are influenced by the increasing concentrations of greenhouse gases in the atmosphere.

For further details, see the following paper:

Oskar Franklin, Torgny Näsholm, Peter Högberg, Mona N. Högberg. Forests trapped in nitrogen limitation - an ecological market perspective on ectomycorrhizal symbiosis. New Phytologist, 2014; DOI: 10.1111/nph.12840

Posted by Tim Sandle