Abstract

Spruce budworm (Choristoneura fumiferana) is the main defoliator of conifer trees in North American boreal forests, affecting extensive areas and causing marked losses of timber supplies. In 2017, spruce budworm affected more than 7 million ha of Eastern Canadian forest. Defoliation was particularly severe for black spruce (Picea mariana (Mill.) B.S.P.), one of the most important commercial trees in Canada. During the last decades, intensive forest exploitation practices have created vast stands of young balsam fir (Abies balsamea (L.) Mill.) and black spruce. Most research focused on the impacts of spruce budworm has been on mature stands; its effects on regeneration, however, have been neglected. This study evaluates the impacts of spruce budworm on the defoliation of conifer seedlings (black spruce and balsam fir) in clearcuts. We measured the cumulative and annual defoliation of seedlings within six clearcut black spruce stands in Quebec (Canada) that had experienced severe levels of defoliation due to spruce budworm. For all sampled seedlings, we recorded tree species, height class, and distance to the residual forest. Seedling height and species strongly influenced defoliation level. Small seedlings were less affected by spruce budworm activity. As well, cumulative defoliation for balsam fir was double that of black spruce (21% and 9%, respectively). Distance to residual stands had no significant effect on seedling defoliation. As insect outbreaks in boreal forests are expected to become more severe and frequent in the near future, our results are important for adapting forest management strategies to insect outbreaks in a context of climate change.

Keywords

black spruce; balsam fir; clearcut; edge effect; forest damages; forest dynamics; global change; natural disturbances; sustainable forest management; seedlings

Published in

Forests
2019, Volume: 10, number: 10, article number: 850
Publisher: MDPI

SLU Authors

• Montoro Girona, Miguel

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • Université du Québec à Chicoutimi

Associated SLU-program

SLU Plant Protection Network


Sustainable Development Goals

SDG15 Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss
SDG13 Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.3390/f10100850

Permanent link to this page (URI)

https://res.slu.se/id/publ/103050