by Marie-Claude Boileau | 2 February 2021
Published in Applied Geochemistry 125: 104860. https://doi.org/10.1016/j.apgeochem.2020.104860
How calcium (Ca) uptake by trees in eastern Canadian forests has responded to decades of atmospheric acid deposition and its sharp decrease that started three decades ago is still largely unknown. Here, we tested a novel approach based on the measurements of Ca and strontium (Sr) concentrations and Sr isotope signature (87Sr/86Sr ratio) in sequential extracts of sugar maple tree rings and soils to assess changes in Ca availability and sources through time. The study was conducted at three sites showing a gradient of one order of magnitude in soil mineral weathering fluxes and exchangeable pools of Ca. We found that wood Ca and Sr concentrations increased with Ca and Sr concentrations in the exchangeable fraction (NH4Cl extracts) of the top mineral soil across sites. In addition, wood 87Sr/86Sr ratio was strongly correlated with 87Sr/86Sr ratio of this soil fraction. Both Ca and Sr concentrations in the exchangeable fraction of the wood decreased from pith to bark at all sites, whereas no trend was observed for the wood residual fraction. This was interpreted as a result of radial mobility of Ca in sapwood rather than a decline in the uptake of Ca and Sr by tree roots over time. The 87Sr/86Sr ratio of tree rings slightly increased over time only at the site with the higher soil exchangeable Ca pool, suggesting an increase in the contribution of soil mineral weathering relative to atmospheric deposition. In contrast with our hypothesis, our results show i) no evidence of pronounced changes in the relative contribution of the atmospheric vs. soil mineral weathering Ca components over time at the site with the smallest soil exchangeable Ca pools; and ii) the difficulty of assessing the temporal changes in the availability and the sources of Ca from sequential extractions of the wood due to a dynamic exchange process of Sr (and therefore Ca) between the exchangeable and residual fractions of the wood.
by Marie-Claude Boileau | 2 February 2021
Published in Forest Ecology and Management 482: 118872. https://doi.org/10.1016/j.foreco.2020.118872
The demand for wood products continues to increase globally. Productivity of forest plantations can be greater than that of naturally regenerated forests. Plantation forestry could thus be employed to meet up to 75% of global wood supply by 2050. The resilience of natural forests could jeopardize plantation productivity. If the plantation scenario is not oriented in the same direction as the natural successional trajectories that are driven by resilience, then naturally regenerating tree species could recover to the detriment of planted species. Unproductive plantations will likely generate sustainability issues, as they must provide ecosystem services (e.g., wood fiber production) while being economically viable for forest management to be sustainable. Our general objective of our study was to assess whether resilience of natural forests can jeopardized plantation productivity. We studied successional trajectories in recent, young and old black spruce plantations that are located within the balsam fir ecological region on balsam fir ecological site types. To compare with a plantation scenario that was more susceptible to aiming in the same direction as resilience-driven successional trajectories, we also studied successional trajectories in recent, young and old black spruce plantations that are not only located within the balsam fir ecological region, but on black spruce ecological site types. Successional trajectories on balsam fir ecological site types pointed towards recovery of balsam fir and white birch, to the detriment of black spruce. Successional trajectories on black spruce ecological site types pointed towards the recovery of black spruce. Thus, we showed that resilience of natural forests could jeopardize plantation productivity when the plantation scenario is not oriented in the same direction as resilience-driven successional trajectories. It also can enhance plantation productivity when the regime is oriented in the same direction as resilience-driven successional trajectories. To ensure that plantations are economically viable and promote sustainability, forest managers should thus favor plantation scenarios that point in the same direction as resilience-driven successional trajectories. Finally, we suggest adopting such scenarios, and stress that it would also be necessary to develop regimes that would promote sustainability in the context of alternative successional trajectories that will undoubtedly arise because of global changes.
by André Boily | 11 December 2020
In the Sustainable Forest Management Strategy, the Ministère des Forêts, de la Faune et des Parcs provided for the introduction of a provincial wood production strategy. The first version of that strategy, known as the Québec Draft Wood Production Strategy, aims to maintain the socio-economic benefits provided by the wood processing sector by developing the full potential of Québec’s forests. A further aim is to ensure the viability of the Government’s silvicultural investments, among other things by responding to recommendations made by Québec’s Auditor General following her 2017 audit of the silvicultural work. After producing the Draft of the Québec Wood Production Strategy, the Ministry sought comments and opinions from the main forest sector partners and stakeholders. This Consultation Report presents a compilation of the comments and opinions received during the summer of 2018.
by Claire Morin | 11 December 2020
Innovative, the Québec Timber Production Strategy will help to address the future of timber production in Québec with confidence, especially by creating wealth for the society and contributing to the tackle against climate change.
The Québec Timber Production Strategy is an ambitious initiative designed to produce more timber with the desired characteristics, through profitable investments, while developing the forest’s existing potential to create more wealth.
by Claire Morin | 15 October 2020
Published in The Forestry Chronicle 95(2): 113-123. https://doi.org/10.5558/tfc2019-018
We used the two-step shelterwood cutting to release conifer advance growth and limit the development of trembling aspen (Populus tremuloïdes) suckers in a stratified mixed aspen – conifer stand. This study presents the effects of the final cut, applied 12 years after the establishment cut, on the 5-year response of advance regeneration and aspen sucker development. Suckering was inversely proportional to the intensity of the establishment cut, with 19 000, 14 900 and 6800 stems/ha two years after the final cut, respectively, in the initial removal of 35%, 50% and 65% basal area. By year 5 however, the treatment effect on stem density was no longer significant due to high aspen mortality in the 35% and 50% cuts. At this time, the density of conifer stems taller than 100 cm was comparable to that of aspen stems in the 35% and 50% cuts, while conifers dominated the 65% cut. Standing mortality was higher for hardwood (22–28%) than for conifer (4–9%) advance growth, except in the uncut control (14% and 9%, respectively), while windthrow averaged 4% and 8%, respectively, in the three partial cuts without being related to treatment. Small merchantable conifer stems (diameter at breast height – DBH 9.1–15.0 cm) that were retained were most affected by windthrow, but overall losses were found acceptable considering DBH and height growth of the surviving stems. This study confirms that the two-step shelterwood cutting that secures conifer advance regeneration should be considered to limit hardwood conversion in the boreal mixedwood forest.
