Boreal forests of eastern Canada revisited: old growth, nonfire disturbances, forest succession, and biodiversity

Abstract

Boreal forests have commonly been described as dominated by monospecific postfire stands that are reburnt well before other ecological process than those occurring immediately after fire can take place. Research undertaken over the last 30 years has given us a very different perspective of the complexity of Canadian boreal forests. Old-growth forests are common and their development is controlled by nonfire disturbances. Consequently, monospecific even-aged stands can develop towards more diversified uneven-aged stands with increasing time since fire. This complex disturbance regime, including both fire and nonfire disturbances, is partially responsible for a higher than expected biodiversity (e.g., understory) in these forests. The dominating forest management model in Canadian boreal forests, based on clear-cut harvesting and regeneration of short rotation even-aged stands, does not reflect the complexities of the disturbance-succession cycle observed in Canadian natural boreal forests.Résumé : Les forêts boréales sont généralement considérées comme étant une large étendue de peuplements monospécifi-ques issus de feux qui vont rebrûler bien avant que des processus écologiques autres que ceux liés aux feux ne puissent avoir cours. Les recherches réalisées au cours des 30 dernières années révèlent une perspective très différente. Les vieilles forêts sont abondantes et elles sont souvent contrôlées par des régimes de perturbations autres que les feux. À mesure que le temps s'écoule après les feux, les peuplements équiennes et monospécifiques se transforment graduellement en peuplements plus diversifiés et à structure inéquienne. Ce régime de perturbations complexe qui inclut à la fois le feu et d'autres types de perturbations crée une biodiversité (ex., sous-bois) plus élevée que généralement attendue. Le modèle d'aménage-ment actuellement préconisé dans la forêt boréale canadienne basé sur la coupe totale, et la reconduction en rotation courte de peuplements monospécifiques équiennes, s'éloigne passablement de la complexité de la dynamique naturelle observée.

Ecosystem management in paludified boreal forests: enhancing wood production, biodiversity, and carbon sequestration at the landscape level

“…Over the last two decades, the landscape and stand dynamics of the forests of the northern Clay Belt have been extensively studied Maycock 1978, Carleton andMaycock 1980;Belleau et al 2011;Bergeron and Fenton 2012). While some studies have focused on natural disturbances (Carcaillet et al 2001;Bergeron et al 2004) and stand dynamics (Harper et al 2003;Gauthier et al 2004;Lecomte et al 2006a), others sought to contrast the effects of silvicultural treatments with those of natural disturbances (Nguyen-Xuan et al 2000;Bescond et al 2011;Simard et al 2001;Arseneault et al 2012;Lafleur et al 2010bRenard et al 2016).…”

“…Forest-dependent species of bryophytes, lichens and invertebrates make up the most species rich groups across the landscape (Paradis and Work 2011;Bergeron and Fenton 2012). These groups respond to fire severity and changes in forest structure (Boudreault et al 2009;Paradis and Work 2011;Bergeron and Fenton 2012;Fenton and Bergeron 2013;Doblas-Miranda and Work Fig. 4 In paludified forests, stand dynamics can be synthesized using the cohort approach (Bergeron et al 1999;Harvey et al 2002).…”

“…Modified from Lecomte et al (2006a), Simard et al (2009), andFenton et al (2009) 2015). Since each of these species are associated with specific stand structures, community composition is greatly influenced by soil burn severity and time elapsed since fire (Bergeron and Fenton 2012;Boudreault et al 2009;Paradis and Work 2011;Fenton and Bergeron 2013;Doblas-Miranda and Work 2015).…”

“…Indeed, old-growth boreal forests typically harbor species (both plants and animals) assemblages that differs from younger forests . For instance, Bergeron and Fenton (2012) found that stand-level species richness of both vascular and nonvascular plants increased significantly 150 years after fire. Old-growth boreal forests, therefore, can harbor a diverse understory community that is absent in younger stands.…”

Unravelling the past to manage Newfoundland’s forests for the future

“…Our understanding of the role of natural disturbances in the boreal forest biome has evolved from a rather simplistic paradigm where large catastrophic fires produced predominantly young forest landscapes, to a more complex paradigm involving multiple disturbances interacting with each other and with climate, producing an equally complex landscape composed of a mosaic of stand ages and forest structure (Bergeron and Fenton 2012). These paradigms are not completely mutually exclusive, and parts of both may apply together or individually depending on scale and geography.…”