title: Warming shifts 'worming': effects of experimental warming on invasive earthworms in northern North America.
abstract: Climate change causes species range shifts and potentially alters biological invasions. The invasion of European earthworm species across northern North America has severe impacts on native ecosystems. Given the long and cold winters in that region that to date supposedly have slowed earthworm invasion, future warming is hypothesized to accelerate earthworm invasions into yet non-invaded regions. Alternatively, warming-induced reductions in soil water content (SWC) can also decrease earthworm performance. We tested these hypotheses in a field warming experiment at two sites in Minnesota, USA by sampling earthworms in closed and open canopy in three temperature treatments in 2010 and 2012. Structural equation modeling revealed that detrimental warming effects on earthworm densities and biomass could indeed be partly explained by warming-induced reductions in SWC. The direction of warming effects depended on the current average SWC: warming had neutral to positive effects at high SWC, whereas the opposite was true at low SWC. Our results suggest that warming limits the invasion of earthworms in northern North America by causing less favorable soil abiotic conditions, unless warming is accompanied by increased and temporally even distributions of rainfall sufficient to offset greater water losses from higher evapotranspiration.
authors.affiliation: 1] German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany [2] Institute for Biology, University of Leipzig, Johannisallee 21, 04103 Leipzig, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Eisenhauer
authors.affiliation: University of Minnesota, Department of Forest Resources, 1530 Cleveland Avenue N., St. Paul, MN 55108, USA.
authors.forename: Artur
authors.initials: A
authors.lastname: Stefanski
authors.affiliation: National Park Service, Natural Resource Stewardship and Science, 1201 Oakridge Drive, Fort Collins, CO 80525, USA.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Fisichelli
authors.affiliation: University of Minnesota, Department of Forest Resources, 1530 Cleveland Avenue N., St. Paul, MN 55108, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Rice
authors.affiliation: University of Minnesota, Department of Forest Resources, 1530 Cleveland Avenue N., St. Paul, MN 55108, USA.
authors.forename: Roy
authors.initials: R
authors.lastname: Rich
authors.affiliation: 1] University of Minnesota, Department of Forest Resources, 1530 Cleveland Avenue N., St. Paul, MN 55108, USA [2] University of Western Sydney, Hawkesbury Institute for the Environment, Penrith, NSW, 2751, Australia.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Reich
mesh_terms: D063147:Animal Distribution; D000818:Animals; D000845:Annelida; D018533:Biomass; D057232:Global Warming; D058865:Introduced Species; D008910:Minnesota; D012987:Soil / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D012987:Soil; D014867:Water