Canadian Forest Service Publications
Non-native species in Canada's boreal zone: diversity, impacts, and risk. 2014. Langor, D.W.; Cameron, E.K.; MacQuarrie, C.J.K.; McBeath, A.; McClay, A.S.; Peter, B.; Pybus, M.; Ramsfield, T.; Ryall, K.L.; Scarr, T.A.; Yemshanov, D.; DeMerchant, I.; Foottit, R.G.; Pohl, G.R. Environmental Reviews 22(4):372-440.
Issued by: Northern Forestry Centre
Catalog ID: 35564
Available from the Journal's Web site. †
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More than 1180 non-native species, mostly of Palaearctic origin, have been recorded from the boreal zone of Canada, with the highest diversity on the island of Newfoundland and in the southern boreal zone of Ontario and Quebec. The non-native biota of the boreal zone (and of Canada in general) is poorly known in terms of species composition and distribution. A large proportion of species are associated with disturbed anthropogenic habitats such as urban areas, agricultural landscapes, transportation and communication corridors, and industrial developments. Natural habitats in the boreal zone have a high degree of resistance to invasion compared with those of other Canadian zones, likely owing to harsh climates, low light levels, poor soil nutrient availability, low soil pH, low productivity, and dense covering of the ground by plants, especially bryophytes. Of the relatively few non-native species that have successfully colonized the boreal zone, many decline greatly in abundance after a few years, suggesting biotic resilience. To date the boreal zone has shown the least resistance and resilience to large vertebrates (moose and white-tailed deer) translocated to islands, diseases of vertebrates, and earthworms. In general, the ecological impacts of non-native species on the boreal zone have been poorly studied, and there are few examples where such impacts are evident. Likewise, there has been little attempt to quantify the economic impacts of non-native species in either the boreal zone or in Canada as a whole. In the few cases where management measures have been implemented for highly destructive non-native species, results have been somewhat successful, especially where classical biological control measures have been implemented against insects on trees. Chemical and mechanical management measures have had only limited success in localized situations. Management resources are most effectively applied to reducing the risk of introduction. The risk to the boreal zone posed by future new non-native species is increasing with the warming climate and the fast and direct transport of goods into the boreal zone from points of origin. Five recommendations are provided to address recognized gaps concerning non-native species.
Plain Language Summary
This paper reviews and synthesizes information in published literature and provides some new analyses about the diversity, impacts, and risk of non-native species in Canada’s boreal zone. Although at least 1180 non-native species have colonized the boreal zone, including plants, vertebrates, insects, spiders, fungi, slugs, and snails, non-native species diversity is higher in other more southern and coastal ecozones. Excluding plants and vertebrates, non-native species of other groups, such as insects and fungi, are poorly inventoried. Most non-native species are in urban and semi-urban areas; few have successfully invaded natural ecosystems, suggesting that the boreal zone has high resistance to non-native species. The boreal zone also has resilience to colonization by non-native species. High resistance and resilience of the boreal zone mean that impacts of non-native species are relatively low there compared to other ecozones. The greatest ecological impacts of non-native species in the boreal zone are caused by translocation of native boreal mammals to islands and wildlife diseases or parasites. Risk to the boreal zone posed by non-native species is low but likely increasing with increased transportation, trade, and climate change. Earthworm invasion of natural forests has high potential for significant ecological impacts, but there is a dearth of information. There are some non-native species management successes (especially in classical biocontrol using insect parasitoids and herbivores), and establishment prevention is the best management strategy.