Modélisation de stratégies d'aménagement durable dans un contexte de paludification : une analyse par coûts-bénéfices afin de maintenir un maximum de forêt fermée

Authors: Schab, Alexis
Advisor: Desrochers, AndréGauthier, SylvieRaulier, Frédéric
Abstract: Successive disturbances such as successive fires can hinder the natural regeneration of forest stands in the boreal forest. Futhermore, in managed forests, logging is a disturbance that has the potential to affect the regenerative capacity of forests. The combined effect of natural disturbance and management is therefore expected to have an impact on the opening of forests coverand to hinder the ability to achieve sustainable forest management notably by reducing the amount of productive forest stands. In addition, in the boreal environment, the accumulation of organic matter (paludification) causes constraints in growth of harvested stands and can affect forest productivity. These events are only partially integrated into the computations of annual allowable cuts. It is therefore important to evaluate the impacts of not considering the potential opening of stands by disturbances and the loss of productivity caused by paludification on a managed forest landscape. In addition, it isuseful to develop management and evaluate strategies able to promote the restoration of stands through growth and adequate regeneration while being economically viable. To do this, the computation of annual allowable cut is done in a model that integrates the fire regime, the paludification process, forest harvesting and regeneration failure to measure the robustness of different management strategies. Three management strategies focused on reforestation are developed and tested, one that corresponds to the current strategy (REF scenario), one based on the accessibility of the areas to be treated (ACC scenario) and the last one, which consists to return all the burned and paludified areas to production via planting (TOT scenario). The results are analyzed with different indicators of success (volume harvested, proportion of closed, open and paludified areas, reforestation costs, productivity index) and expressed as medians to ensure a reasonable level of protection. After 150 years, territory’s productivity decreases for scenarios REF and ACC (-7.6 % and -2.5 %) and increases for TOT scenario (+ 0.9 %). Harvesting paludified area without specific modalities concerning regeneration failure and stand opening may result in a sharp rise in open stands (+ 8% of the territory in 50 years) compromising the objectives of sustainable development. The strategy of reforesting accessible areas appears to be the most likely to achieve sustainable forest management targets by taking into account operational feasibility.The results suggest that despite the computation of annual allowable cuts every 5 years, the harvesting history of the study area has led to the arrival of a critical period in the management of paludified stands. Finally, I showed that using the absolute maximum potential volume (VMPA) as a productivity index made it possible to anticipate easily problems much earlier than with the usual indices of possibility calculations
Document Type: Mémoire de maîtrise
Issue Date: 2020
Open Access Date: 14 February 2020
Grantor: Université Laval
Collection:Thèses et mémoires

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