Forest fires are an important disturbance in the boreal forest. They are influenced by climate, weather, topography, vegetation, surface deposits, and human activities. In return, forest fires affect ...the climate through emission of gases and aerosols, and changes in surface albedo, soil processes, and vegetation dynamics. The net effect of these factors is not yet well established but seems to have caused a negative feedback on climate during the 20th century. However, an increase in boreal forest fires is predicted by the end of the 21st century, possibly changing the effect of fires on climate change to a positive feedback that would exacerbate global warming. This review presents (1) an overview of fire regimes and vegetation succession in boreal forests; (2) the effects on climate of combustion emissions and post-fire changes in ecosystem functioning; (3) the effects of fire regime variations on climate, especially on carbon stock and surface albedo; (4) an integrative approach of fire effects on climate dynamics; and (5) the implications of increased fire activity on global warming by calculating the radiative forcing of several factors by 2100 in the boreal region, before discussing the results and exposing the limits of the data at hand. Generally, losses of carbon from forest fires in the boreal region will increase in the future and their effect on the carbon stock (0.37 W/m2/decade) will be greater than the effect of fire on surface albedo (−0.09 W/m2/decade). The net effect of aerosol emissions from boreal fires will likely cause a positive feedback on global warming. This review emphasizes the importance of feedbacks between fires and climate in the boreal forest. It presents limitations and uncertainties to be addressed in future studies, particularly with regards to the effect of CO2fertilization on forest productivity, which could offset or mitigate the effect of fire.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
There is a pressing need for a better understanding of changing forest fire regimes worldwide, especially to separate the relative effects of potential drivers that control burned areas. Here we ...present a meta-analysis of the impacts of climate fluctuation and Euro-Canadian settlement on burned areas from 1850 to 1990 in a large zone (>100 000 km2) in northern temperate and boreal forests of eastern Canada. Using Cox regression models, we tested for potential statistical relationships between historical burned areas in 12 large landscapes (reconstructed with dendrochronological data) with climate reconstructions, changes in the Euro-Canadian population, and active suppression (all reconstructed at the decadal scale). Our results revealed a dominant impact of climate fluctuations on forest burned areas, with the driest decades showing fire hazards between 5 to 15 times higher than the average decades. Comparatively, the Euro-Canadian settlement had a much weaker effect, having increased burned areas significantly only during less fire-prone climate conditions. During periods of fire-prone climate, burned areas were maximum independent of fluctuations in Euro-Canadian populations. Moreover, the development of active fire suppression did not appear to reduce burned areas. These results suggest that a potential increase in climate moisture deficit and drought may trigger unprecedented burned areas and extreme fire events no matter the effects of anthropogenic ignition or suppression.
Major environmental changes affect the health and capacity of ecosystems to sustain Indigenous people's well‐being in boreal landscapes. Collaboration between Indigenous communities and researchers ...could help assessing and mitigating the consequences of environmental changes.
We used Driver Pressure State Impact (DPSI) conceptual models to compare the perspectives of Indigenous and scientific communities on environmental changes in boreal landscapes of Quebec, Canada.
The Indigenous DPSI model emerged from interviews with local land‐use experts from two Indigenous communities. The scientific model was informed by the publication topics of expert researchers.
We compared the Indigenous and scientific models and exposed convergences and divergences between perspectives. Forestry was identified as a major driver of change in both models. Most issues related to mining, hydro‐power and forest road development were specific to the Indigenous model. Climate change and wildfires were of greater interest in the scientific model.
Convergences between the perspectives of Indigenous and scientific communities are conducive to collaborative research. Divergences could be addressed through reciprocal knowledge transfer activities, which would lead to research that better aligns with the concerns and needs of Indigenous communities.
Read the free Plain Language Summary for this article on the Journal blog.
Résumé
Des changements environnementaux majeurs affectent la santé des écosystèmes et leur capacité à soutenir le bien‐être des peuples autochtones dans les paysages boréaux. La collaboration entre les communautés autochtones et les chercheurs contribue à mieux évaluer et atténuer les conséquences de ces changements.
Nous avons comparé les perspectives de communautés autochtones et de la communauté scientifique sur les changements environnementaux dans les paysages boréaux du Québec, Canada en faisant appel à des modèles conceptuels de type Driver Pressure State Impact (DPSI).
Le modèle conceptuel autochtone a été dégagé d'entrevues avec des experts locaux de l'utilisation du territoire provenant de deux communautés. Le modèle scientifique a été développé à partir des domaines d'expertise des chercheuses et chercheurs qui travaillent sur les paysages boréaux de la région.
Nous avons comparé les modèles autochtone et scientifique afin d'en exposer les convergences et les divergences. La foresterie a été identifiée comme un moteur majeur de changement dans les deux modèles. La plupart des enjeux liés à l'exploitation minière, à l'hydroélectricité et au développement des chemins forestiers étaient spécifiques au modèle autochtone. Les changements climatiques et les incendies forestiers étaient plus présents dans le modèle scientifique.
Les convergences entre les perspectives des communautés autochtones et scientifique sont propices à la recherche collaborative. Les divergences pourraient être abordées grâce à des activités de transfert réciproque des connaissances, ce qui mènerait à des recherches mieux alignées sur les préoccupations et les besoins des communautés autochtones.
Read the free Plain Language Summary for this article on the Journal blog.
Monitoring of fur-bearing species populations is relatively rare due to their low densities. In addition to catch data, trappers' experience provides information on the ecology and status of the ...harvested species. Fisher (Pekania pennanti) and American marten (Martes americana) are mustelids that are sensitive to forest management and therefore considered to be ecological indicators of forest health. Fisher populations have increased in eastern North America since the early 2000s and this could have resulted in a northeastern extension of the species' range and increased overlap with marten's range. Moreover, habitats of both species are subject to natural and anthropogenic disturbances. The objective of this study was to document the knowledge held by local trappers in the northern area of sympatry between fisher and marten to identify factors that could explain variation in populations of the two species and interactions between them.
Forty-one semi-directed interviews with Indigenous and non-Indigenous trappers in the Abitibi-Témiscamingue region of western Quebec (Canada), at the northern limit of the overlapping ranges of the two mustelid species.
Trappers highlighted the lack of exclusivity of marten and fisher to coniferous forests, although marten is more closely associated with them than is fisher. Fisher apparently also takes advantage of open environments, including agroforestry systems. Moreover, climate change increases the frequency of freeze-thaw events that cause the formation of an ice crust on the snow surface, which favors fisher movements.
The fisher was identified as a competitor and even a predator of the marten. Furthermore, the fisher is less affected than the marten by forest management, and it also seems to benefit from climate change to a greater extent.
Eastern white pine (Pinus strobus L.) is a cultural keystone tree species in the forests of eastern North America, providing numerous ecosystem services to Indigenous people. White pine abundance in ...the landscape has considerably decreased over the last few centuries due to overharvesting, suppression of surface fires, extensive management, and plantation failure. The Kitcisakik Algonquin community of western Quebec is calling for restoration and sustainable management of white pine on its ancestral territory, to ensure provision of associated ecosystem services. We present five white pine restoration and management scenarios taking into account community needs and ecological types: (1) natural regeneration of scattered white pines to produce individuals of different sizes and ages used as medicinal plants; (2) protection of supercanopy white pines used as landmarks and for providing habitat for flagship wildlife species, and younger individuals left as regeneration and future canopy trees; (3) the uniform shelterwood system to create white pine-dominated stands that provide habitat for flagship wildlife species and support cultural activities; (4) under-canopy plantations to yield mature white pine stands for timber production; (5) mixed plantations to produce forests with aesthetic qualities that provide wildlife habitat and protect biodiversity.
Conservation initiatives led by Indigenous peoples are a relatively recent phenomenon gaining momentum around the world. Initiatives to establish Indigenous protected areas are also taking root in ...Canada. We studied the Akumunan Biodiversity Reserve (ABR) in the province of Quebec to assess (1) the approach followed by the Essipit Innu First Nation (EIFN) Band Council to implement the ABR; (2) the EIFN’s vision that led to the creation of the ABR; and (3) the role the EIFN would like to play in the governance of the ABR. Six focus groups conducted with 22 community members have shown that the process which led to the creation of the ABR was fraught with challenges. The EIFN’s vision for the ABR is holistic — “everything” must be protected to respect the memory of the Elders and ensure natural resource sustainability. To ensure the respect of this vision, the community wants to play a leading role in governing the ABR. The EIFN faced many challenges, notably administrative hurdles, opposition due to cultural and value differences, lack of long-term funding, and disregard for the relationship that Indigenous people have with the land. Respecting EIFN’s vision also demands that traditional activities on the land be allowed to continue in protected areas, in order to guarantee that the identity, culture, health, and well-being of current and future generations will be maintained. The community management model developed by the EIFN Band Council provides useful insights on the process leading to the acknowledgement of the Indigenous Protected and Conserved Area status. Moreover, it could be a source of inspiration for other Indigenous conservation projects.
•Essipit Innu First Nation (EIFN) initiated the Akumunan Biodiversity Reserve (ABR).•EIFN opted to avoid conflict and work within the existing regulatory framework.•Permanent protection status for ABR took 20 years due to administrative hurdles.•EIFN's holistic vision simultaneously protects biological and cultural diversity.•EIFN still has a limited role in ABR governance and wants full power delegation.
La relation privilégiée des peuples autochtones avec le territoire, coeur de leur identité, est mal comprise et compromise par les nouvelles formes d’occupation du territoire depuis le contact avec ...les Eurocanadiens. Le rôle et la place des femmes autochtones dans la gouvernance du territoire et la gestion des ressources naturelles sont méconnus, voire occultés. L’analyse thématique de 32 entrevues avec des femmes des trois communautés atikamekw a montré : 1) que les femmes atikamekw ont un fort lien d’attachement au territoire ; 2) qu’elles ont dû s’adapter rapidement aux bouleversements de leur mode de vie ; 3) qu’elles tiennent à perpétuer la transmission des savoirs atikamekw ; et 4) qu’elles ont un rôle à jouer dans la prise de décision locale et territoriale et qu’elles valorisent leur leadership politique. Des solutions sont proposées afin d’atténuer le sentiment d’insécurité territoriale et culturelle des femmes atikamekw et de mettre en valeur leurs savoirs en lien avec le territoire et sa gestion, et ce, afin de « retrouver l’équilibre » essentiel à la transmission de l’identité et de la culture atikamekw.
Le Programme de sécurité du revenu des chasseurs et piégeurs cris (PSR) a été instauré afin de soutenir le mode de vie traditionnel. Toutefois, plusieurs femmes iiyiyuu-iinuu sont insatisfaites de la ...gestion du programme, affirmant qu’il ne tient pas suffisamment compte de leurs réalités. Ce projet visait à documenter l’utilisation du territoire par les femmes iiyiyuu-iinuu, leurs perceptions du PSR et leurs suggestions pour l’améliorer. Les femmes iiyiyuu-iinuu jouent un rôle essentiel dans le mode de vie traditionnel et les activités qu’elles pratiquent sur le territoire sont loin d’être accessoires. Elles sont notamment actives dans la transmission des savoirs et de la culture, piliers de l’identité. Elles ont soulevé plusieurs critiques, notamment au sujet des critères d’admissibilité, des règles de gestion et du niveau des prestations. Elles souhaitent que des améliorations soient apportées au programme pour que leur rôle sur le territoire soit reconnu à sa juste valeur.
Postglacial vegetation colonization that followed ice retreat and proglacial lakes drainage in north-eastern America occurred rapidly, more rapidly than expected based on the modern dispersal ...capacities of boreal mixedwood trees. Paleo-islands from proglacial Lake Ojibway in Québec (Canada) were afforested early, before the final drainage of the lake. We hypothesized that these paleo-islands could have acted as outposts of migration and thus, could explain the rapid afforestation of lowlands observed. To determine if postglacial colonization occurred as a south-north front from the southern margin of Lake Ojibway or if islands acted as migration outposts, we estimated the date of first arrival of the main taxa of the current boreal mixedwood forest. We studied southern sites never covered by proglacial Lake Ojibway, sites that were islands within Lake Ojibway, and northern lowland sites that were liberated after the final drainage of proglacial Lake Ojibway. Taxa arrival was estimated as a sharp rise of the pollen percentage or as the occurrence of macro-remains within the sediments of small lakes dated with radiocarbon. Then we compared migration scenarios where colonization occurred gradually from south to north from the southern margin of proglacial Lake Ojibway and where paleo-islands of Lake Ojibway were first colonized through long-distance dispersal, thus becoming sources of seeds readily available to colonize lowland sites after the final drainage of Lake Ojibway. Finally, we compared the migration rates from the scenarios with the current mean dispersal capacities of the studied taxa. The migration rates estimated without taking the paleo-islands into account are too slow to explain the rapid afforestation observed following the final drainage of proglacial Lake Ojibway. Only the migration rates estimated from the scenarios with paleo-islands were comparable to the current mean dispersal capacity of the boreal mixedwood taxa. Thus, paleo-islands acted as stepping stones during postglacial migration, which explains why the lowlands were rapidly colonized. Larger paleo-islands and those located closer to the southern margin of the proglacial Lake were colonized first, in line with the theory of island biogeography.
•Paleo-islands early afforestation solves the rapid postglacial migration observed.•Paleo-islands acted as stepping stones during postglacial migration.•Paleo-islands colonization patterns follow the Theory of Island Biogeography.•Larger and closer islands from the proglacial Lake Ojibway were colonized first.
Climate changes are expected to progressively increase extreme wildfire frequency in forests. Finding past analogs for periods of extreme biomass burning would provide valuable insights regarding ...what the effects of warming might be for tree species distribution, ecosystem integrity, atmospheric greenhouse gas balance, and human safety. Here, we used a network of 42 lake-sediment charcoal records across a ∼2000 km transect in eastern boreal North America to infer widespread periods of wildfire activity in association with past climate conditions. The reconstructed fluctuations in biomass burning are broadly consistent with variations in ethane concentration in Greenland polar ice cores. Biomass burning fluctuations also significantly co-varied with Greenland temperatures estimated from ice cores, at least for the past 6000 years. Our retrospective analysis of past fire activity allowed us to identify two fire periods centered around 4800 and 1100 BP, coinciding with large-scale warming in northern latitudes and having respectively affected an estimated ∼71% and ∼57% of the study area. These two periods co-occurred with widespread decreases in mean fire-return intervals. The two periods are likely the best analogs for what could be anticipated in terms of impacts of fire on ecosystem services provided by these forests in coming decades.
PDF
