, Volume 150, Issue 1, pp 78–88 | Cite as

Divergent nonlinear responses of the boreal forest field layer along an experimental gradient of deer densities

  • Jean-Pierre TremblayEmail author
  • Jean Huot
  • François Potvin
Plant Animal Interactions


The early responses of the field layer to changes in biotic and abiotic conditions are key determinants of the future composition and structure of forests where sustained heavy browsing pressure has depauperated the shrub understory. We investigated the relationships between white-tailed deer density and field layer plant community dynamics in boreal forests managed for wildlife and timber production. We hypothesized that the growth and reproduction of field layer plants are either: (H1) directly proportional to deer density, or (H2) related to deer density through nonlinear relationships or (H3) through nonlinear relationships with thresholds. We tested these hypotheses using data from a controlled browsing experiment involving a gradient of deer densities (0, 7.5, 15, 27 and 56 deer km−2) in interaction with timber harvesting conducted on Anticosti Island, Canada. In recent clearcuts, the dominant responses of the field layer plants were exponential recovery in growth and reproduction with decreasing deer densities. The abundance of browse-tolerant species such as grasses was positively related to deer density, suggesting an apparent competitive gain. These results support the prediction from our second hypothesis, although the presence of ecological thresholds should not be ruled out. Rapid changes in the early successional stages have potentially long-term consequences on successional patterns through processes such as the modulation of germination and early establishment success of seedlings from later successional species. Quantitative data as those presented here are essential for the development of ecosystem management prescriptions. On Anticosti Island, reduction of local deer densities to levels <15–7.5 deer km−2 in the first 3 years following timber harvesting appears to be compatible with the regeneration dynamics of this system although lower levels of deer densities may be required for the conservation of browse-sensitive plant species.


Boreal forest Grazing Odocoileus virginianus Plant-herbivore interactions Succession 



This research was supported by an Industrial Research Chair grant to J.H. and supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), Produits forestiers Anticosti Inc. (PFA), Université Laval, Centre d’études nordiques, and Ministère des Ressources naturelles et de la Faune du Québec. J.P.T. received scholarships from NSERC and the Fonds québécois de la recherche sur la nature et les technologies during this study. The Société des établissements de plein air du Québec, Pourvoirie du Lac Geneviève and Comité de gestion de la chasse sur le territoire des résidents de l’Île d’Anticosti provided logistical support. Many members and staff of the NSERC-PFA Industrial Research Chair contributed to field work. G. Daigle from the Service de Consultation Statistique at U. Laval helped with the analyses. We are grateful to Steeve Côté, Karen Harper, Alison Hester, John Pastor, Nathalie Pettorelli and Robert Weladji for their comments on previous versions of the manuscript. The experiments reported in this paper comply with the current laws and regulations in Quebec, Canada.

Supplementary material

442_2006_504_MOESM1_ESM.doc (238 kb)
Supplementary material


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Jean-Pierre Tremblay
    • 1
    • 2
    • 4
    Email author
  • Jean Huot
    • 1
    • 2
  • François Potvin
    • 1
    • 3
  1. 1.Chaire de recherche industrielle CRSNG – Produits forestiers Anticosti, Département de biologieUniversité LavalQuebec CityCanada
  2. 2.Centre d’études nordiquesUniversité LavalQuebec CityCanada
  3. 3.Ministère des Ressources naturelles et de la FauneQuebec CityCanada
  4. 4.Institutt for biologiNTNUTrondheimNorway

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