Regional and local patterns of ectomycorrhizal fungal diversity and community structure along an altitudinal gradient in the Hyrcanian forests of northern Iran

Authors

  • Mohammad Bahram,

    1. Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai, 51005 Tartu, Estonia
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  • Sergei Põlme,

    1. Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai, 51005 Tartu, Estonia
    2. Natural History Museum of Tartu University, 46 Vanemuise, 50014 Tartu, Estonia
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  • Urmas Kõljalg,

    1. Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai, 51005 Tartu, Estonia
    2. Natural History Museum of Tartu University, 46 Vanemuise, 50014 Tartu, Estonia
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  • Shahin Zarre,

    1. Department of Plant Sciences, School of Biology, College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
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  • Leho Tedersoo

    1. Institute of Ecology and Earth Sciences, University of Tartu, 40 Lai, 51005 Tartu, Estonia
    2. Natural History Museum of Tartu University, 46 Vanemuise, 50014 Tartu, Estonia
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Author for correspondence:
Mohammad Bahram
Tel: +372 737 6222
Email: bahram@ut.ee

Summary

  • Altitudinal gradients strongly affect the diversity of plants and animals, yet little is known about the altitudinal effects on the distribution of microorganisms, including ectomycorrhizal fungi.
  • By combining morphological and molecular identification methods, we addressed the relative effects of altitude, temperature, precipitation, host community and soil nutrient concentrations on species richness and community composition of ectomycorrhizal fungi in one of the last remaining temperate old-growth forests in Eurasia.
  • Molecular analyses revealed 367 species of ectomycorrhizal fungi along three altitudinal transects. Species richness declined monotonically with increasing altitude. Host species and altitude were the main drivers of the ectomycorrhizal fungal community composition at both the local and regional scales. The mean annual temperature and precipitation were strongly correlated with altitude and accounted for the observed patterns of richness and community.
  • The decline of ectomycorrhizal fungal richness with increasing altitude is consistent with the general altitudinal richness patterns of macroorganisms. Low environmental energy reduces the competitive ability of rare species and thus has a negative effect on the richness of ectomycorrhizal fungi. Because of multicollinearity with altitude, the direct effects of climatic variables and their seasonality warrant further investigation at the regional and continental scales.

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