Earthworm Invasions in Northern Hardwood Forests: a Rapid Assessment Method

• Published in: Natural areas journal Vol. 33; no. 1; pp. 21 - 30
• Main Authors: Loss, Scott R, Hueffmeier, Ryan M, Hale, Cindy M, Host, George E, Sjerven, Gerald, Frelich, Lee E
• Format: Journal Article
• Language: English
• Published: Bend, OR Natural Areas Association 2013; Natural Aeras Association
• Subjects: adverse effects; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; biomass; Conservation, protection and management of environment and wildlife; earthworm sampling methods; earthworms; forest ecosystems; forest litter; Forestry; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; hardwood forests; invasive earthworms; Lumbricus rubellus; Lumbricus terrestris; northern hardwood forests; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; rapid methods; RESEARCH ARTICLE; United States; Deciduous forest; Biological invasion; Method; Annelida; Oligochaeta; Invasion; Earthworm; Invasive species; Lumbricus rubellus; invasive earthworms; earthworm sampling methods; Invertebrata; Sampling; Environmental monitoring; northern hardwood forests; Lumbricus terrestris; Environmental protection
• ISSN: 0885-8608; 2162-4399
• DOI: 10.3375/043.033.0103

Non-native earthworm invasions in north-temperate North America cause substantial adverse effects to hardwood forest ecosystems. Quantification of invasions is necessary for understanding impacts and identifying remnant earthworm-free areas, but existing sampling techniques are effort-intensive and/or environmentally damaging. We: (1) developed and applied a protocol that allows rapid classification of earthworm invasion into five stages based primarily on visual assessment of the forest floor, (2) sampled earthworms to test whether the protocol's stages can predict invasion by different species, and (3) assessed relationships between individual forest floor characteristics and presence of different earthworm species. Based on differences in biomass among points assigned to different stages, the 5-stage classification protocol accurately identified the onset of invasion by Lumbricus rubellus and Lumbricus terrestris, the species of greatest management concern in the northern Midwest. Except for middens as a predictor of L. terrestris presence, no forest floor variable was useful by itself for assessing invasions. The 5-stage protocol provides an efficient approach for assessing earthworm invasions in hardwood forests of the U.S. northern Midwest, can be implemented with minimal training, and serves as a blueprint for similar protocols in other regions experiencing earthworm invasions.