Fine roots, arbuscular mycorrhizal hyphae and soil nutrients in four neotropical rain forests: patterns across large geographic distances

Authors

  • Jennifer S. Powers,

    Corresponding author
    1. Department of Ecology and Evolution, State University of New York–Stony Brook, Stony Brook, NY 11794-5245, USA;
    2. Present address: Department of Soil, Water & Climate, University of Minnesota, St Paul, MN 55108, USA
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  • Kathleen K. Treseder,

    1. Department of Ecology and Evolutionary Biology and Department of Earth System Science, University of California, Irvine, Irvine, CA 92697, USA;
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  • Manuel T. Lerdau

    1. Department of Ecology and Evolution, State University of New York–Stony Brook, Stony Brook, NY 11794-5245, USA;
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Author for correspondence:
Jennifer S. Powers Tel: +1 612 6247902 Fax: +1 612 6252208 Email: powers@umn.edu

Summary

  • • It is commonly hypothesized that stand-level fine root biomass increases as soil fertility decreases both within and among tropical forests, but few data exist to test this prediction across broad geographic scales. This study investigated the relationships among fine roots, arbuscular mycorrhizal (AM) fungi and soil nutrients in four lowland, neotropical rainforests.
  • • Within each forest, samples were collected from plots that differed in fertility and above-ground biomass, and fine roots, AM hyphae and total soil nutrients were measured.
  • • Among sites, total fine root mass varied by a factor of three, from 237 ± 19 g m−2 in Costa Rica to 800 ± 116 g m−2 in Brazil (0–40 cm depth). Both root mass and length were negatively correlated to soil nitrogen and phosphorus, but AM hyphae were not related to nutrients, root properties or above-ground biomass.
  • • These results suggest that understanding how soil fertility affects fine roots is an additional factor that may improve the representation of root functions in global biogeochemical models or biome-wide averages of root properties in tropical forests.

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