The effect of fertilization on the below-ground diversity and community composition of ectomycorrhizal fungi associated with western hemlock (Tsuga heterophylla) |
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Authors: | Shannon H A Wright Shannon M Berch Mary L Berbee |
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Institution: | (1) Department of Botany, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada;(2) Research Branch Laboratory, Ministry of Forestry, 4300 North Road, Victoria, BC, V8Z 5J3, Canada |
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Abstract: | Fertilization typically reduces ectomycorrhizal diversity shortly after its application but less is known about its longer-term
influence on fungal species. Long-term effects are important in forests where fertilizer is rarely applied. We compared fungal
species composition in western hemlock control plots with plots last fertilized 7 years ago with nitrogen (N) or nitrogen
plus phosphorus (N + P). The N + P fertilization had a significant lingering effect, increasing the tree size and foliar P
content of the western hemlocks. From ectomycorrhizal roots of 24-year-old trees from northern Vancouver Island, Canada, we
identified fungi from 12 samples per treatment, by amplifying, cloning, and sequencing fungal ribosomal DNA fragments, placing
sequences with 97% or more identity in the same operational taxonomic unit (OTU). Diversity was high across treatments; we
detected 77 fungal OTUs, 52 from ectomycorrhizal genera, among 922 clone sequences. The five most frequent OTUs were similar
in abundance across treatments. Only 19 OTUs matched any of the 197 previously reported ectomycorrhizal species of western
hemlock. Species composition but not diversity in nitrogen plus phosphorus plots differed significantly from control or nitrogen
plots. Two Cortinarius OTUs were indicator species for nitrogen plus phosphorus plots and presence of Cortinarius cinnamomeus was correlated with control or nitrogen plots. After 7 years, fertilization history had made no detectable difference in
ectomycorrhizal fungal diversity, but long-lasting changes in environment resulting from fertilization had a lingering effect
on fungal ectomycorrhizal species composition.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Ectomycorrhizal diversity Clone library Species definition Species composition Fertilization |
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