Cumulative effects of chronic deer browsing and clear-cutting on regeneration processes in second-growth white spruce stands Martin Barrette a,b,⇑ , Louis Bélanger a,b , Louis De Grandpré c , Jean-Claude Ruel d a Laboratoire d’aménagement intégré, Département des Sciences du Bois et de la Forêt, 2405 de la Terrasse, Université Laval, Québec, QC G1V 0A6, Canada b Chaire de Recherche Industrielle CRSNG-Produits Forestiers Anticosti, Département de Biologie, 1045 Ave. de la Médecine, Université Laval, Québec, QC G1V 0A6, Canada c Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., Québec, QC G1V 4C7, Canada d Centre d’étude de la Forêt, Département des Sciences du Bois et de la Forêt, 2405 de la Terrasse, Université Laval, Québec, QC G1V 0A6, Canada article info Article history: Received 11 April 2014 Received in revised form 13 June 2014 Accepted 14 June 2014 Keywords: White spruce White-tailed deer Forest regeneration processes Recalcitrant understory layer Parklands Resilience abstract Interactions between multiple disturbances can alter resilience mechanisms, thereby triggering alterna- tive successional pathways. Regeneration processes are important mechanisms of forest resilience because they drive successional pathways. On Anticosti Island, chronic browsing by introduced white- tailed deer (Odocoileus virginianus) shifted composition of understory regeneration of overmature balsam fir (Abies balsamea) forests toward dominance by white spruce (Picea glauca). Historic clear-cutting of these altered forests generated mature second-growth white spruce stands. However, the cumulative effect of chronic deer browsing and recent clear-cutting on regeneration processes of mature second- growth white spruce stands has not yet been evaluated. Our objective is to evaluate if regeneration processes would enable white spruce stands to recover from the cumulative effects of these two disturbances. We studied regeneration in relation to seed availability, substrate suitability for seedling establishment, and substrate availability in mature second-growth white spruce stands and recent clear-cuts of mature second-growth white spruce stands. Our results indicate regeneration failure in both ecosystems, which can be explained by a lack of suitable rotten logs for sufficient establishment of white spruce seedlings. Hence, the cumulative effects of chronic deer browsing and clear-cutting of mature second-growth white spruce stands have altered regeneration processes and triggered an alternative successional pathway toward parklands, i.e., partial deforestation. We propose shelterwood cuttings that create nurse logs should be investigated to maintain white spruce stands without planting. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Interactions between multiple disturbances can alter resilience mechanisms of forests, thereby triggering alternative successional pathways (Paine et al., 1998; Tremblay et al., 2007; Buma and Wessman, 2011). Resilience is the capacity of a system to absorb disturbance and reorganize so that the same structure and func- tions are essentially recovered, e.g., forest recovering to forest fol- lowing perturbation (Holling, 1973; Gunderson, 2000). Regeneration processes are important mechanisms of forest resil- ience because they drive successional pathways (Buma and Wessman, 2011; Hidding et al., 2013). For example, cervids such as white-tailed deer (Odocoileus virginianus) can shift the composi- tion of understory regeneration by selectively browsing seedlings (Tremblay et al., 2007; Nuttle et al., 2014), while forest manage- ment practices can change the composition and density of regener- ation through diverse silvicultural scenarios (Boucher et al., 2009; Lundmark et al., 2013; Rist and Moen, 2013). Interaction between these two disturbances could potentially alter regeneration processes, triggering alternative successional pathways that move the system toward assemblages of species that have not co- occurred historically. The occurrence of such novel ecosystems can represent a threat to biodiversity and ecosystem services that are provided by preindustrial forests (Hobbs et al., 2006; Bridgewater et al., 2011). In this context, a recent cause for concern is increasing cervid densities in the forests of North America (Côté et al., 2004; McLaren et al., 2004; Chollet and Martin, 2012), which increases the probability for potential interactions between cervid browsing and forest management. Following the introduction of 200 white-tailed deer into the for- ests of Anticosti Island (Quebec) at the end of the 19th century, http://dx.doi.org/10.1016/j.foreco.2014.06.020 0378-1127/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Present Address: Direction de la Recherche Forestière, Ministère des Forêts, de la Faune et des Parcs, 2700, rue Einstein, Bureau C-1.105.2, Québec QC G1P 3W8, Canada. Tel.: +1 418 643 7994/6689; fax: +1 418 643 2165. E-mail addresses: martin.barrette@mrn.gouv.qc.ca (M. Barrette), Louis.Belan- ger@sbf.ulaval.ca (L. Bélanger), louis.degrandpre@rncan.gc.ca (L. De Grandpré), Jean-Claude.Ruel@sbf.ulaval.ca (J.-C. Ruel). Forest Ecology and Management 329 (2014) 69–78 Contents lists available at ScienceDirect Forest Ecology and Management journal homepage: www.elsevier.com/locate/foreco