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| Titel |
Ecological and geochemical impacts of exotic earthworm dispersal in forest ecosystems of Eastern Canada |
| VerfasserIn |
Melanie Drouin, Martine Fugere, Line Lapointe, Mark Vellend, Robert L. Bradley |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121351
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| Publikation (Nr.) |
 EGU/EGU2016-30.pdf |
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| Zusammenfassung |
| In Eastern Canada, native earthworm species did not survive the Wisconsin glaciation, which
ended over 11,000 years ago. Accordingly, the 17 known Lumbricidae species in the province
of Québec were introduced in recent centuries by European settlers. Given that natural
migration rates are no more than 5–10 m yr−1, exotic earthworm dispersal across the
landscape is presumed to be mediated by human activities, although this assertion
needs further validation. In agroecosystems, earthworms have traditionally been
considered beneficial soil organisms that facilitate litter decomposition, increase nutrient
availability and improve soil structure. However, earthworm activities could also
increase soil nutrient leaching and CO2 emissions. Furthermore, in natural forest
ecosystems, exotic earthworms may reduce organic forest floors provoking changes in
watershed hydrology and loss of habitat for some faunal species. Over the past decade,
studies have also suggested a negative effect of exotic earthworms on understory
plant diversity, but the underlying mechanisms remain elusive. Finally, there are
no studies to our knowledge that have tested the effects of Lumbricidae species
on the production of N2O (an important greenhouse gas) in forest ecosystems.
We report on a series of field, greenhouse and laboratory studies on the human
activities responsible for the dispersal of exotic earthworms, and on their ecological /
geochemical impacts in natural forest ecosystems. Our results show: (1) Car tire
treads and bait discarded by fishermen are important human vectors driving the
dispersal of earthworms into northern temperate forests; (2) Exotic earthworms
significantly modify soil physicochemical properties, nutrient cycling, microbial
community structure and biomass; (3) Earthworm abundances in the field correlate
with a decrease in understory plant diversity; (4) Lumbricus terrestris, an anecic
earthworm species and favorite bait of fishermen, reduces seed germination and
seedling survival of some temperate and boreal trees species; (5) The abundance of L.
terrestris correlates with higher potential rates of N2O production. Taken collectively,
our data provide scientific evidence that earthworm dispersal mitigation strategies
are required to conserve the ecological integrity of forest ecosystems in Eastern
Canada. |
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