Canadian Forest Service Publications
Missing forest cover gains in boreal forests explained. 2018. Guindon, L.; Bernier, P.Y.; Gauthier, S.; Stinson, G.; Villemaire, P.; Beaudoin, A. Ecosphere 9: e02094.
Issued by: Laurentian Forestry Centre
Catalog ID: 39021
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A recent global study reported a net difference between areas of forest cover loss and of forest cover gain of about 3.6% of total forest area across the boreal biome, and of 5.6% for Canada, over a 12-yr period. Net losses of this magnitude should be of concern given the importance of this biome in global biogeochemical cycles linked to climate change. Our analysis for Canada fails to support these results and suggests that post-harvest recovery of tree cover is generally strong, while post-fire recovery of tree cover is weaker but nevertheless prevalent. We find that current large area remote sensing methodologies can fail to properly recognize post-disturbance recovery from non-forest to forest status in low-productivity boreal forests when using short time series. With climate change and human impacts intensifying around the world, it is urgently important to be able to reliably distinguish temporary forest cover loss followed by naturally slow recovery from forest decline requiring policy action. The analysis was in large part based on the new Canada Landsat Disturbance product in which fires and harvest since 1984 are mapped at 30-m resolution (https://doi.org/10.23687/add1346b-f632-4eb9-a83d-a662b38655ad).
Plain Language Summary
In this study, the researchers observed a generalized and rapid regrowth of the boreal forest cover after cutting, as well as a generalized, albeit slower regrowth in burned areas. These results do not align with those of a recent global study, according to which Canada sustained a net forest cover loss of approximately 5.6% in its boreal forest and 3.6% in its circumboreal forest over a 12 year-period. The researchers also demonstrated that these alleged significant net losses were in fact the result of methodological issues related to the difficulty of detecting forest cover regrowth in the boreal forest over a short period.
Current large-scale remote detection methodologies cannot always accurately distinguish whether or not regrowth has occurred in the aftermath a forest cover disturbance. This fault is all the more obvious when the analysis is based on images taken over a short period. As the impact of climate change and human activity intensifies worldwide, it becomes urgent to be able to make these distinctions with greater reliability.