Effects of post-harvest silviculture on use of boreal forest stands by amphibians and marten in Ontario

Abstract

Much of the southern boreal forest is composed of second-growth stands that have been subjected to a variety of silvicultural treatments ranging from cut and leave to scarification, planting, and tending with herbicides. We have limited understanding of the effects that these treatments may have on wildlife species, as a result of changes to forest structures and species composition. Forest amphibians, generally, and the American marten (Martes americana) are species for which there has been long-standing concern about the effects of forest management. We examined the long-term effects at stand and landscape scales of a range of silviculture intensities on these species by comparing the relative abundances of some amphibians and habitat use by marten in forests that were about 32 to 50 years old. American toads (Bufo americanus) appeared to be unaffected by long-term changes in habitat structure and composition owing to silvicultural techniques. We observed lower relative abundance of wood frogs (Rana sylvatica) in treated stands 20 to 30 years old than in all other stands including uncut old forests. However, abundance in treated stands more than 32 years old did not differ from untreated or uncut stands. This effect may have resulted from lower moisture levels in treated young stands. Marten seemed to positively respond to post-harvest planting and tending treatments, suggesting that basic silviculture provided habitat attributes, notably a higher conifer content, which was favourable to marten.Key words: post-harvest silviculture, marten, wood frog, American toad, herbicide, boreal, woody debris, Ontario RÉSUMÉLa majeure partie du sud de la forêt boréale est composée de peuplements de seconde venue qui ont connu plusieurs traitements sylvicoles allant de la coupe à blanc au scarifiage, suivi de plantation et entretien au moyen d'herbicides. Nous comprenons en partie les effets que ces traitements pourraient entraîner sur les espèces fauniques, suite à des modifications de la structure et de la composition des peuplements. Les amphibiens du milieu forestier, de façon générale, et la martre d' Amérique (Martes americana) constituent des espèces pour lesquelles des études ont été entreprises depuis longtemps sur les effets de l'aménagement forestier. Nous avons étudié les effets à long terme au niveau du peuplement et de l' écosystème de l'intensité des travaux sylvicoles sur ces espèces en comparant l'abondance relative de certains amphibiens et de l'habitat utilisé par la martre dans des peuplements âgés de 32 à 50 ans. Le crapaud d' Amérique (Bufo americanus) a semblé ne pas être affecté par les changements à long terme de la structure et de la composition de l'habitat suite aux travaux sylvicoles. Nous avons observé une abondance relative plus faible chez la grenouille des bois dans les peuplements traités de 20 à 30 ans par rapport aux autres peuplements incluant les vieilles forêts non exploitées. Cependant, l'abondance dans les peuplements de plus de 32 ans n' était pas différente de celle des peu...

Effects of natural resource development on the terrestrial biodiversity of Canadian boreal forests

“…Populations of toads in managed stands appeared to be sustainable while those of wood frogs were low, suggesting a long-term negative effect. On the other hand, Thompson et al (2008) found no differences in capture rates of American toads or wood frogs in regenerating stands at least 32-50 years following harvest in north-eastern Ontario boreal forests, compared with capture rates in old unmanaged stands, suggesting no long-term effects of forest management on either species. An explanation of the disparate results of these two studies could be that the western Ontario boreal receives about half the precipitation that falls in the eastern Ontario boreal.…”

“…Managed landscapes with minimal old forests generally supported fewer marten than landscapes with a large proportion of old-forest patches (e.g., Thompson and Harestad 1994;Thompson 1994;Potvin et al 2000;Godbout and Ouellet 2008;Thompson et al 2008). In Newfoundland, however, marten inhabited a landscape with less than 35% mature or older forests (Hearn et al 2010).…”

Commoditization and the Origins of American Silviculture

“…Many forest-dwelling species are dependent on the presence of snags, downed logs, and/or both fine and coarse woody debris (Janowiak & Webster, 2010;Jones, Hanberry, & Demarais, 2009;Tremblay, Ibarzabal, & Savard, 2010;Vanderwel, Malcolm, Caspersen, & Newman, 2010). Other species are dependent on the availability of particular tree species or the presence of a minimum number of trees of a certain diameter (e.g., Thompson et al, 2008). Many forest species rely on the existence of mast-producing trees and shrubs.…”

Long-term effects of timber harvesting on coarse woody debris dynamics and marten habitat

“…For example, Porter et al (2005) documented a marten population successfully inhabiting a young deciduous forest where they preferentially used habitat structures characteristic of older forests. Other studies reporting marten use of younger stands suggest that downed logs, standing snags, and a high conifer content (Chapin et al 1997;Payer and Harrison 2003;Thompson et al 2008) are the key to the effective use of younger stands. However, there is no evidence that large marten populations can be sustained over the long term in intensively managed forests (Thompson et al 2008).…”

“…Other studies reporting marten use of younger stands suggest that downed logs, standing snags, and a high conifer content (Chapin et al 1997;Payer and Harrison 2003;Thompson et al 2008) are the key to the effective use of younger stands. However, there is no evidence that large marten populations can be sustained over the long term in intensively managed forests (Thompson et al 2008). The characteristics and amount of CWD characteristics that contribute to quality marten habitat, also benefit many other species and functions (Bunnell and Houde 2010;Sullivan and Sullivan 2020).…”