Mycorrhizal fungi supply nitrogen to host plants in Arctic tundra and boreal forests: ^sup 15^N is the key signal

Symbiotic fungi's role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but littlestudied in the adjoining boreal forest ecosystem. Along a 570 km north-south transect from the Yukon River to the North Slope of Alaska, the ...N content was strongly reduced...

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Published inCanadian journal of microbiology Vol. 55; no. 1; p. 84
Main Authors Hobbie, John E, Hobbie, Erik A, Drossman, Howard, Conte, Maureen, Weber, J C, Shamhart, Julee, Weinrobe, Melissa
Format Journal Article
LanguageEnglish
Published Ottawa Canadian Science Publishing NRC Research Press 01.01.2009
Subjects
Amino acids
Boreal forests
Flowers & plants
Foliage
Forest ecosystems
Forest soils
Forests
Fungi
Host plants
Microbiology
Nitrogen
Organic matter
Polymers
Soil organic matter
Soils
Temperate forests
Tundra
Understory
Canada
Yukon River
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Summary:Symbiotic fungi's role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but littlestudied in the adjoining boreal forest ecosystem. Along a 570 km north-south transect from the Yukon River to the North Slope of Alaska, the ...N content was strongly reduced in ectomycorrhizaland ericoid mycorrhizal plants including Betula, Salix, Picea mariana (P. Mill.) B.S.P., Picea glauca Moench (Voss), and ericaceous plants. Compared with the ...N content of soil, the foliage of nonmycorrhizal plants (Carex and Eriophorum) was unchanged, whereas content of the ectomycorrhizal fungi was very much higher (e.g., Boletaceae, Leccinum and Cortinarius). It is hypothesized that similar processes operate in tundra and boreal forest, both nitrogen-limited ecosystems: (i) mycorrhizal fungi break down soil polymers and take up amino acids or other nitrogen compounds; (ii) mycorrhizal fungi fractionate against ...N during production of transfer compounds; (iii) host plants are accordingly depleted in ...N; and (iv) mycorrhizal fungi are enriched in ...N. Increased N availability for plant roots or decreased light availability to understory plants may have decreased N allocation to mycorrhizal partners and increased ...N by 3%-4% for southern populations of Vaccinium vitis-idaea L. and Salix. Fungal biomass, measured as ergosterol, correlated strongly with soil organic matter and attained amounts similar to those in temperate forest soils. (ProQuest: ... denotes formulae/symbols omitted.)
ISSN:0008-4166
1480-3275