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Research article2023Peer reviewed

Stronger effect of individual species? traits than shading on aquatic plant community productivity and interspecific competition

Austin, Asa N.; Hansen, Joakim P.; Donadi, Serena; Kautsky, Lena; Eklof, Johan S.

Abstract

Competition is one of the major factors structuring plant communities. Species with similar traits generally compete more intensely and have more similar yield than functionally dissimilar species, which often respond differently to environmental change. Little is known about how the interacting species' traits influence the effect of environmental change on interspecific competition. However, theory predicts that environmental change should lead to more asymmetric competition, by favouring the species best adapted to the particular environmental change. Here we used a mesocosm experiment with three common aquatic plant species from the Baltic Sea (Northern Europe), to test how community productivity and competition asymmetry were affected by functional dissimilarity, individual species' traits and a common stressor: shading. Competition asymmetry was defined as the absolute difference in reductions in yield relative to monocultures of two interacting species. Community productivity decreased and competition asymmetry increased with functional dissimilarity of the interacting species, possibly explained by the traits of the superior species, which had higher specific leaf area, maximum canopy height and primary production rate than the subordinate species. Community productivity was not affected by shading, contrary to our expectation, while competition asymmetry was higher in shaded than ambient conditions. Individual species yield depended on species identity and species combination. Only the shortest species was negatively affected by shading. Thus, by favouring tall-growing species, shading can alter interspecific competition. Together, these findings suggest that non-random species loss following environmental change can be caused by competitive exclusion, in addition to a direct effect of abiotic filtering.

Keywords

Submerged aquatic vegetation; Biotic interactions; Competition; Traits; Functional dissimilarity; Species identity; Shading; Baltic Sea

Published in

Aquatic Botany
2023, Volume: 187, article number: 103647Publisher: ELSEVIER

    Sustainable Development Goals

    SDG14 Life below water

    UKÄ Subject classification

    Ecology
    Botany

    Publication identifier

    DOI: https://doi.org/10.1016/j.aquabot.2023.103647

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/121886