Biological Invasions

, 13:2361

Impacts of non-native plant and animal invaders on gap regeneration in a protected boreal forest

Original Paper

DOI: 10.1007/s10530-011-0048-1

Cite this article as:
Humber, J.M. & Hermanutz, L. Biol Invasions (2011) 13: 2361. doi:10.1007/s10530-011-0048-1


In balsam fir (Abies balsamea)-dominated boreal forests of Gros Morne National Park, Newfoundland (Canada), non-native Cirsium arvense (Canada thistle) has invaded forest gaps. Its management is complicated by the lack of viable control techniques and an overarching issue of gap regeneration failure attributed to browsing by non-native moose (Alces alces). This study identifies the impacts of thistle invasion on balsam fir regeneration and explores protocols to re-establish fir in gaps invaded by thistle and moose. Fir seeds were planted into ten gaps (five natural; five anthropogenic) and the emergence, growth, herbivory damage, and survival of fir was determined for 2 years amongst five treatments (n = 50 plots; 32 seeds/plot): (1) thistle monocultures in gaps; (2) where aboveground thistle biomass was removed; (3) where above- and below-ground thistle biomass was removed; (4) non-invaded areas in gaps; and, (5) adjacent uninvaded forest edges. In addition, 432 fir seedlings (aged 15 months) were transplanted into four forest gaps within the above treatments and followed for 1 year. Results indicate that invasion of C. arvense negatively affects fir emergence and early survival, and may further contribute to continued balsam fir regeneration failure independent of future moose densities. However, older fir seedlings transplanted into thistle monocultures experienced a positive facilitative effect due to the protection thistle provided against small mammal herbivory. Restoration actions that combine moose density reductions with the planting of fir seedlings offers the most viable long-term strategy to re-establish the native forest canopy in thistle-invaded gaps and would likely lead to the eventual decline of shade-intolerant C. arvense.


Non-native invasion Forest regeneration Alces alces Cirsium arvense Protected area Disturbance Abies balsamea 

Supplementary material

10530_2011_48_MOESM1_ESM.pdf (84 kb)
Supplementary material 1 (PDF 84 kb)
10530_2011_48_MOESM2_ESM.pdf (119 kb)
Supplementary material 2 (PDF 118 kb)

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Department of BiologyMemorial University of NewfoundlandSt. John’sCanada
  2. 2.Wildlife Division, Department of Environment & ConservationGovernment of Newfoundland and LabradorCorner BrookCanada

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