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Research article - Peer-reviewed, 2022

Flow-on effects of an introduced tree species: Lodgepole pine plantation affects function and performance of boreal ants

Lofroth, Therese; Andersson, Jon; Roberge, Jean-Michel; Sjogren, Jorgen


Increased demand on forests to produce renewable biomass have accelerated the use of non-native tree species in forestry worldwide, often with negative effects on native biodiversity. In Sweden, the North American lodgepole pine (Pinus contorta Douglas ex. Loudon var. latifolia) was introduced already in the 1970's. Even though the species now covers large areas, effects on native flora and fauna have not been thoroughly evaluated. In this study, we used a large-scale field experiment with 30 paired P. contorta and P. sylvestris stands in central and northern Sweden to study the effects of P. contorta plantation on the abundance and activity of red wood ants of the Formica rufa-group, density and species richness of other ant species, as well as possible effects on the abundance of the specialized ant predator Pella humeralis. We collected epigaeic insects with pit fall traps, surveyed wood ant mound density and volume, and monitored ant activity on trees in all stands. Our analyses revealed a trend with higher mound density in P. sylvestris compared with P. contorta stands, although wood ant worker catch did not differ between the pine species. However, red wood ant activity was significantly higher in P. sylvestris stands, suggesting that P. contorta is not a preferred tree species for the tending of aphids for honeydew. Total ant species richness as well as the catch of Camponotus herculeanus and Myrmica ruginodis were higher in P. sylvestris stands, suggesting that they constitute a more favorable habitat for ants. Ant species richness was negatively influenced by wood ants in P. sylvestris stands only. A similar pattern was shown for C. herculeanus. Myrmica ruginodis was more abundant in P. sylvestris stands only if no thinning had been applied. Wood ant catch was positively correlated with catch of the specialized predatory rove beetle Pella humeralis showing that there is a strong interaction between the predatory beetle and wood ants.Our results suggest that P. contorta plantations impact both red wood ants and associated species and although competition from wood ants is more pronounced in P. sylvestris stands they still constitute a more favorable habitat for most ant species. Thus, large scale plantation of the non-native but closely related P. contorta may negatively impact epigaeic assemblages, a pattern that is not compensated by released competition by dominant red wood ants.


Non-native species; Red wood ants; Scots pine; Lodgepole pine

Published in

Forest Ecology and Management
2022, volume: 512, article number: 120160
Publisher: ELSEVIER

Authors' information

Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies
Andersson, Jonas
Swedish University of Agricultural Sciences, Department of Wildlife, Fish and Environmental Studies

UKÄ Subject classification

Forest Science

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