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Exclusion of root competition increases competitive abilities of subordinate plant species through root–shoot interactions

Authors

  • P. Mariotte,

    Corresponding author
    1. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Site Lausanne, Lausanne, Switzerland
    • Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Lausanne, Switzerland
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  • A. Buttler,

    1. Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Lausanne, Switzerland
    2. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Site Lausanne, Lausanne, Switzerland
    3. Laboratoire de Chrono-Environnement, UMR CNRS 6249, UFR des Sciences et Techniques, 16 route de Gray, Université de Franche-Comté, Besançon, France
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  • D. Johnson,

    1. Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, UK
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  • A. Thébault,

    1. Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory of Ecological Systems (ECOS), Lausanne, Switzerland
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  • C. Vandenberghe

    1. Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Site Lausanne, Lausanne, Switzerland
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pierre.mariotte@epfl.ch

Abstract

Questions

What is the importance of root competition in the competitive abilities of dominant and subordinate species?

Location

Pair-wise greenhouse experiment based on field data from a semi-natural grassland community in the Swiss Jura Mountains (Col du Marchairuz, Switzerland).

Methods

The dominance hierarchy from a mountain wood-pasture ecosystem was used to identify five dominant and three subordinate species. These species were grown in pair-wise combinations under full competition and in the absence of root competition, enabling us to calculate indices of competitive effect and response and overall asymmetry.

Results

Root competition exclusion led to a decrease in the competitive abilities of dominants, whereas subordinates became overall more competitive. Total asymmetry also decreased, indicating reduced competition between the two species groups. The exclusion of root competition increased both below-ground and above-ground growth of subordinates, whereas for dominants below-ground growth was unaffected and above-ground growth decreased.

Conclusions

We demonstrate that root competition through root–shoot competition interactions is an important factor driving the competitive dominance of species and the structure of grazed grassland communities. Locally, reduction of root competition involved in gap creation might explain persistence of subordinate species within the vegetation community and lead to an aggregated spatial pattern of subordinates involved in species co-existence in grasslands.

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