Skip to main content
Research article - Peer-reviewed, 2018

Conifer Regeneration After Experimental Shelterwood and Seed-Tree Treatments in Boreal Forests: Finding Silvicultural Alternatives

Girona, Miguel Montoro; Lussier, Jean-Martin; Morin, Hubert; Thiffault, Nelson

Abstract

Forest regeneration is a key element in achieving sustainable forest management. Partial harvest methods have been used extensively in temperate broadleaf and mixedwood ecosystems to promote regeneration on poorly stocked sites and to maintain forest composition and productivity. However, their effectiveness in promoting conifer establishment has yet to be demonstrated in unmanaged boreal forests, especially those dominated by black spruce (Picea mariana (Mill.) BSP) where constraints for regeneration differ from those found in more meridional regions. We aimed to evaluate conifer seedling density and dimensions, 10 years after the onset of a gradient of silvicultural treatments varying in harvesting intensities, and to identify the critical factors driving the regeneration process. Study blocks of even-aged black spruce stands in the eastern Canadian boreal forest were submitted to three variants of shelterwood harvesting: a seed-tree harvest, a clear-cut and an untreated control. Shelterwood and seed-tree harvesting were combined with spot scarification to promote regeneration. Shelterwood and seed-tree harvesting produced a density of conifer regeneration sufficient to maintain forest productivity, but they did not promote seedling growth. Black spruce was the predominant species in terms of regeneration density, with proportions 3-5x higher than that for balsam fir (Abies balsamea (L.) Mill.). Ten years after treatment, seed-origin black spruce seedlings were abundant in skidding trails, while layers dominated the residual strips. Balsam fir density was not influenced by treatment nor by tree position relative to skidding trails. Balsam fir and black spruce had different responses to treatment in terms of height and diameter, the former exhibiting a better growth performance and larger diameter in the residual strips. Spot scarification createdmicro-sites that had a significant impact on the regeneration process. Overall, our results support that shelterwood and seed-tree harvesting combined with scarification enable adequate regeneration in black spruce stands, confirming these treatments as viable silvicultural alternatives to clear-cutting when required by sustainable forest management objectives.

Keywords

balsam fir; black spruce; ecosystem-based management; even-aged stands; partial cutting; seedling; shade-tolerant species; sustainable forest management

Published in

Frontiers in Plant Science
2018, volume: 9, article number: 1145
Publisher: FRONTIERS MEDIA SA

Authors' information

Université du Québec à Chicoutimi
Lussier, Jean-Martin
Natural Resources Canada
Morin, Hubert
Université du Québec à Chicoutimi
Thiffault, Nelson
Natural Resources Canada

Associated SLU-program

Forest

Sustainable Development Goals

SDG15 Life on land
SDG12 Ensure sustainable consumption and production patterns

UKÄ Subject classification

Forest Science

Publication Identifiers

DOI: https://doi.org/10.3389/fpls.2018.01145

URI (permanent link to this page)

https://res.slu.se/id/publ/96522