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New Phytol. 2017 Apr;214(1):432-442. doi: 10.1111/nph.14343. Epub 2016 Dec 5.

Dominant mycorrhizal association of trees alters carbon and nutrient cycling by selecting for microbial groups with distinct enzyme function.

Author information

1
Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden.
2
Department of Biology, Indiana University, 1001 E Third Street, Bloomington, IN, 47405, USA.
3
Department of Biology, West Virginia University, 53 Campus Drive, Morgantown, WV, 26506, USA.
4
Department of Evolutionary Biology, Uppsala University, Uppsala, 752 36, Sweden.
5
Department of Ecology and Evolutionary Biology, The University of Kansas, 2041 Haworth Hall, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA.

Abstract

While it is well established that plants associating with arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi cycle carbon (C) and nutrients in distinct ways, we have a limited understanding of whether varying abundance of ECM and AM plants in a stand can provide integrative proxies for key biogeochemical processes. We explored linkages between the relative abundance of AM and ECM trees and microbial functioning in three hardwood forests in southern Indiana, USA. Across each site's 'mycorrhizal gradient', we measured fungal biomass, fungal : bacterial (F : B) ratios, extracellular enzyme activities, soil carbon : nitrogen ratio, and soil pH over a growing season. We show that the percentage of AM or ECM trees in a plot promotes microbial communities that both reflect and determine the C to nutrient balance in soil. Soils dominated by ECM trees had higher F : B ratios and more standing fungal biomass than AM stands. Enzyme stoichiometry in ECM soils shifted to higher investment in extracellular enzymes needed for nitrogen and phosphorus acquisition than in C-acquisition enzymes, relative to AM soils. Our results suggest that knowledge of mycorrhizal dominance at the stand or landscape scale may provide a unifying framework for linking plant and microbial community dynamics, and predicting their effects on ecological function.

KEYWORDS:

arbuscular mycorrhizal (AM) fungi; carbon : nitrogen (C : N) ratio; ectomycorrhizal (ECM) fungi; enzyme stoichiometry; ergosterol; extracellular enzymes; fungal : bacterial (F : B) ratio; temperate forest

PMID:
27918073
DOI:
10.1111/nph.14343
[Indexed for MEDLINE]
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