Fire history was reconstructed for an area of 15 000 km2 located in the transition zone between the mixed and coniferous forests in Quebec's southern boreal forest. We used aerial photographs, archives, and dendroecological data (315 sites) to reconstruct a stand initiation map for the area. The cumulative distribution of burnt area in relation to time since fire suggests that the fire frequency has decreased drastically since the end of the Little Ice Age (about 1850) in the entire region. However, a large part of the area was burned between 1910 and 1920 during intensive colonization and when the climate was very conducive to fire. For the period 1920–1945, large fires have mainly been concentrated in the more populated southern area, while few fires have been observed in the virgin coniferous forest in the north. Despite slight differences between the south and the north, fire cycles or the average number of years since fire are not significantly different. Since 1945, there have been far more fires in the south, but the mean fire size was smaller than in the north. These results suggest that the transition between the mixed and coniferous forests observed in the southern boreal forest cannot be explained by a difference in fire frequency, at least during the last 300 years. As climatic factors and species potential distribution did not vary significantly from south to north, we suggest that the transition from mixedwood to coniferous forests is mainly controlled by fire size and severity. Smaller and less severe fires would favor species associated with the mixedwood forests as many need survivors to reinvade burnt areas. The abundance of deciduous species in mixedwood forests, together with the presence of more lakes that can act as firebreaks, may contribute to decreases in fire size and severity. The transition between the two vegetation zones could be related to the initial setting following the vegetation invasion of the area during the Holocene. In this context, the limit of vegetation zones in systems controlled by disturbance regimes such as fires may not have reached a balance with current climatic conditions. Historical legacies and strong positive feedback between disturbance regimes and composition may filter and delay the responses to changes in climate.
Given that fire is the most important disturbance of the boreal forest, climatically induced changes in fire frequency (i.e., area burnt per year) can have important consequences on the resulting forest mosaic age-class distribution and composition. Using archives and dendroecological data we reconstructed the fire frequency in four large sectors along a transect from eastern Ontario to central Quebec. Results showed a dramatic decrease in fire frequency that began in the mid-19th century and has been accentuated during the 20th century. Although all areas showed a similar temporal decrease in area burned, we observed a gradual increase in fire frequency from the west to Abitibi east, followed by a slight decrease in central Quebec. The global warming that has been occurring since the end of the Little Ice Age (~1850) may have created a climate less prone to large forest fires in the eastern boreal forest of North America. This interpretation is corroborated by predictions of a decrease in forest fires for that region of the boreal forest in the future. A longer fire cycle (i.e., the time needed to burn an area equivalent to the study area) has important consequences for sustainable forest management of the boreal forest of eastern Canada. When considering the important proportion of overmature and old-growth stands in the landscape resulting from the elongation of the fire cycles, it becomes difficult to justify clear-cutting practices over all the entire area as well as short rotations as a means to emulate natural disturbances. Alternative practices involving the uses of variable proportion of clear, partial, and selective cutting are discussed.
Cordy Tymstra3, Rob ~c~l~i n e~, Brad ~a w k e s~, Herman stegehuis6, Sherra ~u i n t i l i o~, Sylvie ~a u t h i e r~ and Karl peck9Sustainable forest management in many of Canada's forest ecosystems requires simultaneously miniizing the socioeconomic impacts of fire and maximizing its ecological benefits. A pragmatic approach to addressing these seemingly conflicting objectives is fire-smart forest management. This involves planning and conducting forest management and fire management activities in a fully integrated manner at both the stand and landscape levels. This paper describes the concept of fire-smart forest management, discusses its need and benefits, and explores challenges to effective implementation.Key words: forest fire management, fire-smart forest management, landscape fire assessment, sustainable forest management La pratique du d6veloppement durable clans plusieurs des kosystiimes forestiers du Canada doit minimiser des les impacts socio4conomiques des incendies de for& tout en maximisant leur effets bknkfiques sur le plan kcologique. Afin de rkaliser de concert ces deux objectifs qui semblent contradictoires, une approche pragmatique pourrait &re la solution: l'amknagement forestier intelli-feu (c.-8-d. fire-smart). Cette approche vise la planiflcation et la realisation des activitks d'amknagement forestier et de gestion des incendies de fa~on inGgr6e, tant au niveau des paysages qu'au niveau des peuplements. Cet article pr6sente le concept d'amtnagement forestier intelli-feu, sa nkcessit6 et ses avantages, ainsi que les dkfis qui se posent face 2 sa rnise en pratique.Mots-clb : am6nagement forestier durable, amknagement forestier intelli-feu, kvaluation des incendies au niveau du paysage, gestion des incendies de forst
Within the context of studying the ecological impacts of wildland fires in the boreal forest, a spatial analysis of a major wildfire was conducted. The fire covered nearly 500 km 2 in the north-western part of Quebec’s boreal forest in the summer of 1995. The spatial distribution of different fire impacts on the forest canopy was obtained using timber damage assessment maps. Fire impacts varied throughout the burned area, ranging from areas where trees had completely burned crowns (43%) to remaining patches of trees with green foliage (3%). The effects of local stand and site factors on crown fire, as assessed by the fire impacts, were evaluated using geographic information systems. Despite the large extent and high intensity of the wildfire created by extreme fire weather conditions, stepwise logistic regression and analysis by log–linear models indicated that variations in surface material, stand composition, and estimated stand age played a role in the presence or absence of crowning at the stand level. However, it appears that height and density of stand, as well as topography, did not have a significant influence. Our study presents the variability of fire impacts and its implications, and it provides a better understanding of the relationships between landscape components and fire crowning. Résumé.Dans le cadre de l’étude de la dynamique de la for&ecircumflex;t boréale, une analyse d’un grand incendie a été réalisée. À la fin de l’été 1995, cet incendie a couvert un territoire de près de 500 km 2 dans la partie nord-ouest de la for&ecircumflex;t boréale québécoise. La distribution spatiale des impacts du feu sur la voute forestière a été obtenue à partir de cartes d’évaluation des dommages aux for&ecircumflex;ts causés par le feu. Dans la zone br&ucircumflex;lée, la gamme des impacts de l’incendie varie d’étendues où les arbres présentent des cimes complètement br&ucircumflex;lées (43%) à des secteurs où le feuillage des arbres est demeuré vert (3%). L’effet de facteurs biotiques et abiotiques sur l’occurrence d’un feu de cime a été établi à l’aide d’un système d’information géographique. Une régression logistique pas à pas et une analyse de modèles log-linéaires ont révélé que certaines modalités des dépôts de surface, de la composition et de l’âge du peuplement ont joué un rôle important dans l’occurrence d’un feu de cime au niveau du peuplement. Par contre, il semble que la hauteur et la densité du peuplement, ainsi que la topographie, n’aient pas eu d’effets significatifs. Notre étude met en lumière la variabilité et l’importance des impacts d’un incendie, tout en permettant de mieux comprendre la relation entre les composantes du territoire et le comportement des incendies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.