, Volume 39, Issue 4, pp 841–852 | Cite as

Tree Encroachment Induces Biotic Differentiation in Sphagnum-Dominated Bogs

  • Maya Favreau
  • Stéphanie PellerinEmail author
  • Monique Poulin


This study aims to understand the effects of recent tree encroachment on plant richness and diversity of Sphagnum-dominated bogs isolated in an agricultural landscape. A nested paired sampling design was used to compare plant species richness and beta diversity between open and forested habitats of 14 bogs in southern Québec, Canada. We evaluated the impact of tree encroachment at regional and local scales (between and within bogs, respectively). Tree basal area, canopy openness and stand age were evaluated in forested habitats. We used permutation paired sample t-tests to compare species richness between open and forested sites. Beta diversity was calculated as between-site similarities in composition, and differences were evaluated using tests for homogeneity in multivariate dispersion. Forested habitats had greater species richness than open habitats due to enrichment by facultative and non-peatland species as well as by mid- and shade-tolerant vascular plants. At both scales, this species enrichment was associated with flora differentiation (increase of beta diversity), although at regional scale, this was true for bryophytes only. Tree basal area had a positive influence on forested habitats species richness. These compositional changes are expected to increase similarity between bog flora and upland vegetation, and consequently decrease regional diversity.


Beta diversity Biotic homogenization Multivariate dispersion Species richness Species turnover Tree encroachment 



This research received financial support from the Natural Sciences and Engineering Research Council of Canada (Discovery grant to S. Pellerin: RGPIN-2014-05367 and M. Poulin RGPIN-2014-05663) and the Québec Centre for Biodiversity Science. We are grateful to all landowners, including the Government of Québec, Nature Action and Transport Canada, who allowed us to conduct field sampling on their lands. Our thanks to numerous field assistants, P. Legendre and S. Daigle for statistical advices and K. Grislis for linguistic revision.

Supplementary material

13157_2018_1122_MOESM1_ESM.docx (120 kb)
ESM 1 (DOCX 119 kb)


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Copyright information

© Society of Wetland Scientists 2019

Authors and Affiliations

  1. 1.Institut de recherche en biologie végétaleUniversité de Montréal and Jardin botanique de MontréalQCCanada
  2. 2.Québec Centre for Biodiversity ScienceMcGill UniversityQCCanada
  3. 3.Department of PhytologyUniversité LavalQCCanada

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