New Method Confirms Importance of Fungi in Arctic Nitrogen Cycle

[phantom power]

WOODS HOLE, MA—A new method to calculate the transfer of nitrogen from Arctic mushrooms to plants is shedding light on how fungi living symbiotically on plant roots and transfer vital nutrients to their hosts. The analytical technique, developed by John E. Hobbie, MBL Distinguished Scientist and co-director of the laboratory’s Ecosystems Center and his son, Erik A. Hobbie of the University of New Hampshire, may be applied to nearly all conifers, oaks, beeches, birch and shrubs such as blueberry and cranberry—all nitrogen-poor ecosystems—and will be an important tool for future studies of plant nitrogen supply.

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Previous research has found that when mycorrhizal fungi in the soil take up nitrogen from the soil and transfer it to small trees and shrubs, the heavy nitrogen isotope, nitrogen-15, is reduced in abundance in the plants and enriched in the fungi. Using a mass balance approach, an accounting of material entering and leaving a system, the researchers quantified the transfer of nitrogen and found that 61-86% of the nitrogen in plants at the site entered through fungal symbionts,

“Previous studies at this Arctic site have found a large range of nitrogen isotope content in plants and attributed the range to plants tapping into several different sources of nitrogen in the soil,” says John Hobbie. “Our study indicates that the differences can be attributed mainly to the presence or absence of symbiotic mycorrhizal fungi.”

The researcher’s new technique is shedding light not only on the nitrogen cycle in arctic tundra ecosystems, but can be applied to other nitrogen-poor ecosystems. “In the future, studies of plant nitrogen supply in all nitrogen-poor ecosystems must include these important transfers between plants and fungi,” says Hobbie.

http://www.mbl.edu/inside/what/news/press_releases/2006_pr_05_02.html

[anoraksia53]

1. An important discovery

No doubt this'll be important for other ecosystems, too, and not just ones that are nitrogen poor. Boy do we have a lot to learn about microbes and their importance.