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Invasive earthworms modulate native plant trait expression and competition
  • +4
  • Rike Schwarz,
  • Nico Eisenhauer,
  • Olga Ferlian,
  • Fernando Maestre,
  • Benjamin Rosenbaum,
  • Henriette Uthe,
  • Lise Thouvenot
Rike Schwarz
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig

Corresponding Author:rike.schwarz@idiv.de

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Nico Eisenhauer
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
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Olga Ferlian
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
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Fernando Maestre
Universidad de Alicante
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Benjamin Rosenbaum
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
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Henriette Uthe
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
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Lise Thouvenot
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
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Abstract

Biological invasions have major impacts on a variety of ecosystems and threaten native biodiversity. Earthworms have been absent from northern parts of North America since the last ice age, but non-native earthworms were recently introduced there and are now being spread by human activities. While past work has shown that plant communities in earthworm-invaded areas change towards a lower diversity mainly dominated by grasses, the underlying mechanisms related to changes in the biotic interactions of the plants are not well understood. Here, we used a trait-based approach to study the effect of earthworms on interspecific plant competition and aboveground herbivory. We conducted a microcosm experiment in a growth chamber with a full-factorial design using three plant species native to northern North American deciduous forests, Poa palustris (grass), Symphyotrichum laeve (herb), and Vicia americana (legume), either growing in monoculture or in a mixture of three. These plant community treatments were crossed with earthworm (presence or absence) and herbivore (presence or absence) treatments. Eight out of the eleven above- and belowground plant functional traits studied were significantly affected by earthworms, either by a general effect or in interaction with plant species identity, plant diversity level, and/or herbivore. Earthworms increased the aboveground productivity and the number of inflorescences of the grass P. palustris. Further, earthworms countervailed the increasing effect of herbivores on root tissue density of all species, and earthworms and herbivores individually increased the average root diameter of S. laeve in monoculture, but decreased it in mixture. In this study, earthworm presence gave a competitive advantage to the grass species P. palustris by inducing changes in plant functional traits. Our results suggest that invasive earthworms can alter competitive and multitrophic interactions of plants, shedding light on some of the mechanisms behind invasive earthworm-induced plant community changes in northern North America forests.
25 Jan 2023Submitted to Oikos
26 Jan 2023Submission Checks Completed
26 Jan 2023Assigned to Editor
26 Jan 2023Review(s) Completed, Editorial Evaluation Pending
26 Jan 2023Reviewer(s) Assigned
23 Apr 2023Editorial Decision: Revise Major
22 Jul 20231st Revision Received
24 Jul 2023Submission Checks Completed
24 Jul 2023Assigned to Editor
24 Jul 2023Review(s) Completed, Editorial Evaluation Pending
16 Aug 2023Reviewer(s) Assigned
27 Sep 2023Editorial Decision: Accept