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Global-scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties

Authors

  • Uffe N. Nielsen,

    Corresponding author
    1. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
    2. Department of Biology, Colorado State University, Fort Collins, CO, USA
    3. Hawkesbury Institute for the Environment and School of Science and Health, University of Western Sydney, Penrith, NSW, Australia
    • Correspondence: Uffe N. Nielsen, Hawkesbury Institute for the Environment and School of Science and Health, University of Western Sydney, Penrith NSW 2751, Australia.

      E-mail: u.nielsen@uws.edu.au

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  • Edward Ayres,

    1. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
    Current affiliation:
    1. National Ecological Observatory Network, Boulder, CO, USA
    2. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
    3. Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA
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  • Diana H. Wall,

    1. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
    2. Department of Biology, Colorado State University, Fort Collins, CO, USA
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  • Grace Li,

    1. Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
    2. Department of Biology, Colorado State University, Fort Collins, CO, USA
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  • Richard D. Bardgett,

    1. Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Manchester, UK
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  • Tiehang Wu,

    1. Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, USA
    Current affiliation:
    1. Department of Biology, Georgia Southern University, Statesboro, GA, USA
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  • James R. Garey

    1. Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, USA
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  • Editor: Richard Field

Abstract

Aim

To conduct the first global-scale investigation of soil nematode assemblages using a standardized approach to quantify how environmental and climatic variables influence family assemblage structure in nematodes and determine whether nematode families have restricted distributions.

Location

Global.

Methods

We collected soil nematodes within four 10 m × 10 m plots distributed evenly along a 900-m transect at each of 12 sites representing multiple ecosystem types across a latitudinal gradient (68° N to 77° S) on six continents. We assigned > 28,000 individuals to family level and trophic group morphologically.

Results

We recorded a total of 43 nematode families, but sites varied considerably in family richness (1–30). Families differed in their ranges with 12 families occurring at 10 or more sites, while 14 families occurred at three or fewer sites. Total nematode and trophic group abundances were generally related to soil characteristics, including bulk density and soil moisture, but we found no good predictor of family richness, diversity or evenness at the plot level. Family richness, diversity and evenness were considerably lower in the high-latitude polar desert than elsewhere, but only family diversity showed a significant, albeit weak, latitudinal gradient. Nematode assemblage composition was quite strongly related to climate: 65% and 58% of the variation in assemblage composition across sites could be accounted for by mean annual rainfall and temperature, respectively.

Main conclusions

Nematode families display macroecological patterns similar to other organisms, such as a positive abundance–range size relationship and restricted distribution of some families. Local nematode abundances were related to soil characteristics, but we found no relationships between family richness and environmental or climatic variables. Family composition was related to mean annual rainfall and temperature, suggesting that climate is a good predictor of local assemblage structure. As a result, climate change may have a significant impact on nematode assemblages, with potential implications for ecosystem functioning.

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