Nina Ryzhkova, Hugo Asselin, Adam A. Ali, Alexander Kryshen, Yves Bergeron, Daniela Robles, Sara Pineda-Zapata, Igor Drobyshev. PDO Dynamics Shape the Fire Regime of Boreal Subarctic Landscapes in the Northwest Territories, Canada 2025. Journal of Geophysical Research: Biogeosciences e2024JG008178
DOI : 10.1029/2024JG008178
Abstract Spatially explicit reconstructions of fire activity in northwestern boreal Canada are rare, despite their importance for modeling current and future disturbance regimes and forest dynamics. We provide a dendrochronological reconstruction of historical fire activity along Highway 3 in the Northwest Territories (NWT), Canada, within the boreal subarctic zone. We dated 129 fires that occurred between 1202 and 2015 CE, using samples from 479 fire-scarred living and dead jack pine trees (Pinus banksiana Lamb.). Three distinct periods can be distinguished in terms of historical fire cycle (FC) and fire occurrence. Initially (1340?1440 CE), fire activity was low (FC = 572 years; 1 fire/decade), before increasing notably between 1460 and 1840 (FC = 171 years; 4.45 fires/decade), and even more in recent times (1860?2015 CE; FC = 95 years; 7.63 fires/decade). Climate has been an important factor controlling changes in fire frequency and FC in the NWT since the 1300s. The 1440s and 1850s correspond with periods of increased fire activity synchronized with shifts from negative to positive Pacific Decadal Oscillation (PDO) phases. Since the mid-1800s, human activities may have contributed to the increase in fire activity, but climate remained the leading factor. During the 20th century, years with increased area burned corresponded to periods with drier-than-average conditions associated with positive PDO, suggesting fire activity in the study region is still influenced by climate. Spatial teleconnection patterns among PDO, drought, and large fire years (LFYs) in the NWT reveal persistent relationships between ocean-atmosphere circulation patterns and fire activity. PDO dynamics hold strong potential for predicting regional fire hazards across northwestern North America.
Marianne Vogel, Sébastien Joannin, Mebarek Lamara, Hugo Asselin, Adam A. Ali, Sabrina Leclercq, Cécile Latapy, Frank Richard, Yves Bergeron. Multi-proxy analysis of early Holocene vegetation dynamics on the islands of proglacial Lake Ojibway (northeastern America) 2024. Journal of Quaternary Science Online first
DOI : https://doi.org/10.1002/jqs.3682
ABSTRACT Following deglaciation, lowland sites in eastern Canada that were covered by proglacial Lake Ojibway recorded direct afforestation with boreal mixedwood taxa, without an initial tundra phase, contrary to sites that were never covered by this lake. Because former islands of proglacial Lake Ojibway were colonized by vegetation before lake drainage around 8200?cal a bp, we hypothesized that these paleo-islands went through a non-arboreal phase which eventually transitioned to boreal mixedwoods, hence providing a source of propagules for rapid and later colonization of the lowlands. We carried out a multi-proxy analysis combining pollen, macro-remains, sedimentary ancient DNA and charcoal to document vegetation composition and dynamics on two paleo-islands. Both study sites recorded progressive vegetation establishment starting with a tundra-like phase with only herbs and shrubs, followed by open forests dominated by either larch or pine, culminating with the establishment of the boreal mixedwoods about 300 years before the final drainage of proglacial Lake Ojibway. Fire regimes seem to have partially driven vegetation dynamics and diversity on the paleo-islands. Paleo-islands were sources of propagules, which helps explain how the former Lake Ojibway lowlands were directly colonized by boreal mixedwoods, without an initial tundra phase.
Martin P. Girardin, Dorian Gaboriau, Adam A. Ali, Konrad Gajewski, Michelle Brière, Yves Bergeron, Jordan Paillard, Justin Waito, Jacques Tardif. Boreal forest cover was reduced in the mid-Holocene with warming and recurring wildfires 2024. Commun Earth Environ 176
DOI : 10.1038/s43247-024-01340-8
The hemi-boreal zone, marking North America’s southern boreal forest boundary, has evolved post-glaciation, hosting diverse ecosystems including mixed forests with savannas, grasslands, and wetlands. While human, climate, and fire interactions shape vegetation dynamics therein, specific influences remain unclear. Here we unveil 12,000 years of hemi-boreal zone dynamics, exploring wildfire, vegetation, climate, and human population size interactions at such long time scales. Postglacial biomass burning exhibited episodes of persistent elevated activity, and a pivotal shift around 7000 years ago saw the boreal forest transition to an oak-pine barren ecosystem for about 2000 years before reverting. This mid-Holocene shift occurred during a period of more frequent burning and a sudden uptick in mean annual temperatures. Population size of Indigenous peoples mirrored wildfire fluctuations, decreasing with more frequent burning. Anticipated increases of fire activity with climate change are expected to echo transformations observed 7000 years ago, reducing boreal forest extent, and impacting land use.
Marianne Vogel, Adam A. Ali, Sébastien Joannin, Yves Bergeron, Hugo Asselin. Postglacial vegetation migration facilitated by outposts on proglacial lake islands in eastern North America 2024. Quaternary Science Advances 100164
DOI : 10.1016/j.qsa.2024.100164
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.
Augustin Feussom, Laurent Millet, Damien Rius, Adam A. Ali, Yves Bergeron, Pierre Grondin, Sylvie Gauthier, Olivier Blarquez. An 8500-year history of climate-fire-vegetation interactions in the eastern maritime black spruce–moss bioclimatic domain, Québec, Canada 2023. Ecoscience 1
DOI : 10.1080/11956860.2023.2292354
The eastern, maritime portion of the black spruce – moss bioclimatic domain in Québec (Canada) is characterized by large wildfires with low occurrence. However, it is still poorly understood how climate–fire interactions influenced long-term vegetation dynamics in the boreal forest of eastern Québec. The long-term historical climate–fire–vegetation interactions in this region were investigated using a multiproxy (chironomids, charcoal, and pollen) paleoecological analysis of an 8500-year sediment core. Chironomid-inferred August air temperatures suggest that the warm Holocene Thermal Maximum (HTM; between ca. 7000–4000 cal yr BP) shifted to the cooler Neoglacial period (4000 cal yr BP to present), consistent with other temperature reconstructions across Québec. The shift to spruce-moss forest dominance around 4800 cal yr BP occurred nearly a thousand years before the climatic shift to the Neoglacial period and rather coincided with a shift from frequent low-severity small fires to infrequent but large and severe fire events. Our results suggest that long-term changes in the summer temperature are probably not the main factor controlling fire and vegetation dynamics in eastern Québec. It seems that, throughout the postglacial period, summer temperatures never fell below a threshold that could have induced a significant vegetation response.
La partie orientale et maritime du domaine bioclimatique de la pessière à mousse au Québec (Canada), est caractérisée par des grands incendies à très faible occurrence. Cependant, l’effet des interactions climat-feu sur la dynamique à long terme de la végétation dans la forêt boréale de l’est du Québec est peu connu. A l’aide d’une analyse paléoécologique multiproxies (chironomes, charbon de bois, pollen) d’une carotte sédimentaire de 8500 ans, nous avons documenté les interactions à long terme entre le climat, le feu et la végétation à l’est du Québec. Les températures de l’air du mois d’août reconstituées par les chironomes suggèrent que la période chaude de l’Optimum climatique Holocène (7000-4000 ans avant aujourd’hui (AA)) a cédé place à la période froide du Néoglaciaire (4000 ans AA à l’actuel) en cohérence avec les reconstitutions climatiques réalisées ailleurs au Québec. L’établissement de la pessière à mousses il y a environ 4800 ans s’est produit près d’un millier d’années avant la transition vers le Néoglaciaire et a plutôt coïncidé avec le changement de petits incendies peu sévères fréquents, à de grands incendies sévères peu fréquents. D’après nos résultats, les changements de températures estivales ne semblent pas jouer un rôle prépondérant dans la dynamique de la végétation et des feux dans l’est du Québec. Il semble que, tout au long de la période postglaciaire, les températures estivales n’aient jamais diminué sous un seuil qui aurait induit une réponse significative de la végétation.
Tuomas Aakala, Cécile C. Remy, Dominique Arseneault, Hubert Morin, Martin-Philippe Girardin, Fabio Gennaretti, Lionel Navarro, Niina Kuosmanen, Adam A. Ali, Étienne Boucher, Normunds Stivrins, Heikki Seppä, Yves Bergeron, Miguel Montoro Girona. Millennial-Scale Disturbance History of the Boreal Zone 2023. In: Girona, M.M., Morin, H., Gauthier, S., Bergeron, Y. (eds) Boreal Forests in the Face of Climate Change. Advances in Global Change Research, vol 74. Springer, Cham. 53
DOI : 10.1007/978-3-031-15988-6_2
Long-term disturbance histories, reconstructed using diverse paleoecological tools, provide high-quality information about pre-observational periods. These data offer a portrait of past environmental variability for understanding the long-term patterns in climate and disturbance regimes and the forest ecosystem response to these changes. Paleoenvironmental records also provide a longer-term context against which current anthropogenic-related environmental changes can be evaluated. Records of the long-term interactions between disturbances, vegetation, and climate help guide forest management practices that aim to mirror “natural” disturbance regimes. In this chapter, we outline how paleoecologists obtain these long-term data sets and extract paleoenvironmental information from a range of sources. We demonstrate how the reconstruction of key disturbances in the boreal forest, such as fire and insect outbreaks, provides critical long-term views of disturbance-climate-vegetation interactions. Recent developments of novel proxies are highlighted to illustrate advances in reconstructing millennial-scale disturbance-related dynamics and how this new information benefits the sustainable management of boreal forests in a rapidly changing climate.
Marion Lacand, Hugo Asselin, Gwenaël Magne, Tuomas Aakala, Cécile C. Remy, Heikki Seppä, Adam A. Ali. Multimillennial fire history of northern Finland along a latitude/elevation gradient. 2023. Quaternary Research 108171
DOI : 10.1016/j.quascirev.2023.108171
In boreal environments, wildfires are expected to decrease in frequency and/or size with latitude/elevation, mainly in response to climate, as well as fuel availability and type. Furthermore, fire frequency and biomass burned are supposed to have been higher during warm and dry periods of the Holocene (last ∼ 11,000 years). We tested these assumptions in northern Finland by using charcoal analysis to reconstruct Holocene regional fire regimes from eight lake sediment sequences sampled within four different environments in terms of elevation, latitude and vegetation type: (1) low latitude/mid elevation coniferous forests (Pinus sylvestris and Picea abies); (2) mid latitude/low elevation pine forests (Pinus sylvestris); (3) mid
Marianne Vogel, Hugo Asselin, Sébastien Joannin, Yves Bergeron, Sabrina Leclercq, Cécile Latapy, Adam A. Ali. Early afforestation on islands of proglacial Lake Ojibway as evidence of post-glacial migration outposts. 2023. Holocene 975-985
DOI : 10.1177/09596836231169988
At the end of the last glacial period in the northern hemisphere, meltwater from receding ice sheets accumulated into large proglacial lakes, potentially limiting postglacial afforestation. We explored whether former islands of proglacial Lake Ojibway (Canada) (hilltops in the current landscape) could have acted as migration outposts and thus accelerated the postglacial migration. We extracted sediments from two small lakes located on “paleo-islands” and used XRF to detect changes in soil erosion and vegetation biomass. We also used plant macro-remains and wood charcoal to determine if (and which) tree species colonized the sites and to detect local fire events. Organic sediment accumulation started around 9657 and 9947 cal. yr BP at Lakes Perché and Despériers, respectively, before the level of Lake Ojibway started to decrease and liberate parts of the studied landscape ca 9400 cal. yr BP. Lithogenic elements (Ti, K, Sr, Fe, Zr, and Rb) decreased between the beginning of organic sediment accumulation and 8800–8700 cal. yr BP, indicating reduced soil erosion, possibly due to soil stabilization by vegetation. Then, the S/Ti ratio, a proxy of organic matter increased around 8800 and 8400 cal. yr BP. The earliest tree macro-remains (Larix laricina and Pinus spp.) were found between 9850 and 9500 cal. yr BP. Local fires were detected around 9820 and 8362 cal. yr BP. Early afforestation occurred on the islands of Lake Ojibway, 200 and 450 years before its level started to decrease, confirming that some islands acted as migratory outposts accelerating postglacial migration.
Dorian Gaboriau, Emeline Chaste, Martin-Philippe Girardin, Hugo Asselin, Adam A. Ali, Yves Bergeron, Christelle Hely-Alleaume. Interactions within the climate-vegetation-fire nexus may transform 21st century boreal forests in northwestern Canada. 2023. iScience 26:106807
DOI : 10.1016/j.isci.2023.106807
Dry and warm conditions have exacerbated the occurrence of large and severe wildfires over the past decade in Canada’s Northwest Territories (NT). While temperatures are expected to increase during the 21st century, we lack understanding of how the climate-vegetation-fire nexus might respond. We used a dynamic global vegetation model to project annual burn rates, as well as tree species composition and biomass in the NT during the 21st century using the IPCC’s climate scenarios. Burn rates will decrease in most of the NT by the mid-21st century, concomitant with biomass loss of fire-prone evergreen needleleaf tree species, and biomass increase of broadleaf tree species. The southeastern NT is projected to experience enhanced fire activity by the late 21st century according to scenario RCP4.5, supported by a higher production of flammable evergreen needleleaf biomass. The results underlie the potential for major impacts of climate change on the NT’s terrestrial ecosystems.
Cécile C. Remy, Gwenaël Magne, Normunds Stivrins, Tuomas Aakala, Hugo Asselin, Heikki Seppä, Tomi Luoto, Nauris Jasiunas, Adam A. Ali. Climatic and vegetational controls of Holocene wildfire regimes in the boreal forest of northern Fennoscandia. 2023. Journal of Ecology 111(4):845-860
DOI : 10.1111/1365-2745.14065
Abstract Climate change is expected to increase wildfire activity in boreal ecosystems, thus threatening the carbon stocks of these forests, which are currently the largest terrestrial carbon sink in the world. Describing the ecological processes involved in fire regimes in terms of frequency, size, type (surface vs. crown) and severity (biomass burned) would allow better anticipation of the impact of climate change on these forests. In Fennoscandia, this objective is currently difficult to achieve due to the lack of knowledge of long-term (centuries to millennia) relationships between climate, fire and vegetation. We investigated the causes and consequences of changes in fire regimes during the Holocene (last ~11,000 years) on vegetation trajectories in the boreal forest of northern Finland. We reconstructed fire histories from sedimentary charcoal at three sites, as well as vegetation dynamics from pollen, moisture changes from Sphagnum spore abundance at two sites, and complemented these analyses with published regional chironomid-inferred July temperature reconstructions. Low-frequency, large fires were recorded during the warm and dry mid-Holocene period (8500–4500 cal. year BP), whereas high-frequency, small fires were more characteristic of the cool and wet Neoglacial period (4500 cal. year BP onward). A higher proportion of charcoal particles with a woody aspect—characterizing crown fires—was recorded at one of the two sites at times of significant climatic and vegetational changes, when the abundance of Picea abies was higher. Synthesis. Our results show both a direct and an indirect effect of climate on fire regimes in northern Fennoscandia. Warm and dry periods are conducive to large surface fires, whereas cool and moist periods are associated with small fires, either crown or surface. Climate-induced shifts in forest composition also affect fire regimes. Climatic instability can alter vegetation composition and structure and lead to fuel accumulation favouring stand-replacing crown fires. Considering the ongoing climate warming and the projected increase in extreme climatic events, Fennoscandian forests could experience a return to a regime of large surface fires, but stand-replacing crown fires will likely remain a key ecosystem process in areas affected by climatic and/or vegetational instability.
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Marion Blache, Dorian Gaboriau, Hugo Asselin, Sébastien Joannin, Jean-Sepet Mathis, Martin-Philippe Girardin, Pierre J.H. Richard, Yves Bergeron, Adam A. Ali. Holocene rise and fall of pine in Quebec's northern temperate forest was controlled by fire 26e colloque de la Chaire AFD. Hôtel Forestel, Val-d'Or, Québec. (2024-11-20)
Dorian Gaboriau, Marianne Vogel, Jordan Paillard, Hugo Asselin, Adam A. Ali, Yves Bergeron. Histoire à long terme de la dynamique de la végétation et des incendies aux plus hautes altitudes du nord-ouest du Québec, Canada 17e colloque annuel du CEF, Université du Québec en Outaouais (2024-05-02)
Adam A. Ali Les incendies dans les écosystèmes boréaux : causes et conséquences Axe écologie UQAM (2024-02-21)
Marianne Vogel, Adam A. Ali, Sébastien Joannin, Yves Bergeron, Hugo Asselin. Facilitation de la migration postglaciaire végétale par les avant-postes insulaires d’un lac proglaciaire en Amérique du Nord-Est. 3e rencontre annuelle du Laboratoire International de Recherche sur les Forêts Froides. Station touristique Duchesnay, Québec. (2023-10-03)
Marion Lacand, Hugo Asselin, Damien Rius, Marianne Vogel, Adam A. Ali. Les feux peuvent-ils induire des épisodes d'érosion dans les bassins versants du nord de la Finlande ? 3e rencontre annuelle du Laboratoire International de Recherche sur les Forêts Froides. Station touristique Duchesnay, Québec. (2023-10-03)
Marianne Vogel, Sébastien Joannin, Adam A. Ali, Yves Bergeron, Edith Leclerc, Cécile Latapy, Hugo Asselin. Les premières étapes de la végétation d’anciennes îles du lac Ojibway (Abitibi, Québec) au début de l’Holocène 16e colloque annuel du CEF, Université de Montréal (2023-05-08)
Marianne Vogel, Adam A. Ali, Hugo Asselin, Sabrina Leclercq, Cécile Latapy, Sébastien Joannin, Yves Bergeron. Histoire des paléo-îles du lac proglaciaire Ojibway
(Abitibi, Québec)
premières étapes de la végétation 24e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2022-11-22)
Adam A. Ali Les feux dans les écosystèmes boréaux : causes et conséquences Midi-foresterie (2021-10-26)
Marianne Vogel, Hugo Asselin, Adam A. Ali, Yves Bergeron, Sébastien Joannin. L'histoire des paléo-îles du lac proglaciaire Ojibway (Abitibi) 21e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2019-11-30)
Bi-Tchoko Vincent Evrard Kouadio, Yves Bergeron, Olivier Blarquez, Christelle Hely-Alleaume, Adam A. Ali. Affiche 9
Des outils pour caractériser les différents types de pessières afin de reconstruire et de comprendre leur dynamique à long terme au Canada. 20e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Lorrainville, Québec. (2018-11-30)
Samira Ouarmim, Hugo Asselin, Adam A. Ali, Christelle Hely-Alleaume, Yves Bergeron. 8000 ans d'histoire et très peu de feux en forêt boréale mixte 14e colloque de la Chaire AFD. Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, Québec. (2012-11-29)
Adam A. Ali Feux et dynamiques post-glaciaires de Abies balsamea dans la forêt boréale coniférienne (Nord du Québec) : analyses à haute résolution de charbons de bois et de macrorestes végétaux. Feux et dynamiques post-glaciaires de Abies balsam (2006-02-28)
Faustine Machut, Dorian Gaboriau, Yves Bergeron, Adam A. Ali, Carsten Meyer-Jacob. Effets à long terme des feux de forêt sur la qualité de l'eau dans les lacs de la Forêt d’Enseignement et de Recherche du Lac Duparquet (FERLD), Abitibi-Témiscamingue, Québec, Canada. 26e colloque de la Chaire AFD. Hôtel Forestel, Val-d'Or, Québec.