Skip to Main Content
Demographic disequilibrium caused by canopy gap expansion and recruitment failure triggers forest cover lossAuthor(s): Martin Barrette; Louis Bélanger; Louis De Grandpré; Alejandro A. Royo
Source: Forest Ecology and Management
Publication Series: Scientific Journal (JRNL)
Station: Northern Research Station
View PDF (1.0 MB)
DescriptionIn the absence of large-scale stand replacing disturbances, boreal forests can remain in the old-growth stage over time because of a dynamic equilibrium between small-scale mortality and regeneration processes. Although this gap paradigm has been a cornerstone of forest dynamics theory and practice for decades, evidence suggests that it could be disrupted, threatening the integrity and sustainability of continuous forest cover. The objective of this study was to evaluate the gap dynamics in old-growth boreal forests across a large landscape where deer populations currently exist at high abundance. We hypothesized that chronic deer browsing is limiting recruitment, particularly of palatable species, creating a demographic disequilibrium between canopy mortality and recruitment. We analysed understory regeneration density and distribution in relation to canopy gap size and condition on multiple sample areas within a 360 km2 area of old-growth balsam fir (Abies balsamea [L.] Miller) forest on Anticosti Island, Canada. The combined effect of accelerating canopy gap expansion and recruitment failure created a demographic disequilibrium important enough to cause a loss of forest cover. The forest is now at risk of shifting to alternative successional pathways that seem to be dependent upon gaps size. Rather than sustaining historic balsam fir composition, sucession in 57% of gap area was more susceptible to following a pathway leading toward white spruce parklands, while sucession in the other 43% was more susceptible to following a pathway toward white spruce forests. The occurrence of these novel ecosystems represents a threat to biodiversity and ecosystem services that are provided by preindustrial forests. Climate change could exacerbate these threats by allowing deer to go into as yet unoccupied boreal forests that are driven by gap dynamics. Novel management issues will arise in these boreal ecosystems and challenge forest managers. When the traditional approaches of identifying gaps will not work because the forest itself is losing cover, the method we have developed will help forest managers recognize demographic disequilibrium threatening maintenance of forests.
- Check the Northern Research Station web site to request a printed copy of this publication.
- Our on-line publications are scanned and captured using Adobe Acrobat.
- During the capture process some typographical errors may occur.
- Please contact Sharon Hobrla, email@example.com if you notice any errors which make this publication unusable.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationBarrette, Martin; Bélanger, Louis; De Grandpré, Louis; Royo, Alejandro A. 2017. Demographic disequilibrium caused by canopy gap expansion and recruitment failure triggers forest cover loss. Forest Ecology and Management. 401: 117-124. https://doi.org/10.1016/j.foreco.2017.07.012.
KeywordsAlternative successional pathways, Balsam fir, Canopy openness, Climate change, Novel ecosystems, Regeneration process, White spruce
- Summary of green weights and volumes for five tree species in Michigan.
- Proceedings of the ninth Lake States Forest Tree Improvement Conference, August 22-23, 1969.
- Site-index comparisons for tree species in northern Minnesota.
XML: View XML