Holes in the tundra: Invasive earthworms alter soil structure and moisture in tundra soils

Abstract

Human introductions have resulted in earthworms establishing in the Arctic, species known to cause cascading ecosystem change. However, few quantitative outdoor experiments have been performed that describe how these soil modifying earthworms are reshaping structures in tundra soils. In this study, we used three-dimensional (3-D) X-ray images of soil cores (approximately 10 cm diameter, 20 cm height, N = 48) to assess how earthworms (Aporrectodea sp. and Lumbricus sp.) affect soil structure and macropore networks in an outdoor mesocosm experiment that lasted four summers. Effects were assessed in both shrub-dominated (heath) and herb-dominated (meadow) tundra. Earthworms almost doubled the macroporosity in meadow soils and tripled macroporosity in heath. Interestingly, the fractal dimension of macropores decreased in response to earthworm burrowing in both systems, indicating that the presence of earthworms reduced the geometric complexity in comparison to other pore-generating processes active in the tundra. Observed effects on soil structure occurred along with a dramatically reduced soil moisture content, which was observed the first winter after earthworm introduction in the meadow. Our findings suggest that predictions of future changes in vegetation and soil carbon pools in the Arctic should include major impacts on soil properties that earthworms induce.

Keywords

3D; Bioturbation; Soil-mixing; Abisko; Meadow; Heath; Long-term

Published in

Science of the Total Environment
2023, volume: 859, number: Part 2, article number: 160125

SLU Authors

• Krab, Eveline

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Umeå University

• Larsbo, Mats

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Koestel, Johannes

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Agroscope

Global goals (SDG)

SDG15 Life on land

UKÄ Subject classification

Soil Science
Environmental Sciences

Publication identifier

• DOI: https://doi.org/10.1016/j.scitotenv.2022.160125

Permanent link to this page (URI)

https://res.slu.se/id/publ/120499