1. 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.
2. 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.
3. 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.
4. 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.
5. 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.

Climate change and natural resource extraction are transforming boreal forest landscapes, with effects on Indigenous people’s relationship with the land. Collaborative management could enhance the consideration of Indigenous perspectives and limit negative outcomes of environmental change, but it remains the exception rather than the norm. We addressed barriers to involvement of Indigenous people in land management by developing a method to enhance communication and trust, while favouring bottom-up decision-making. We partnered with the Abitibiwinni and Ouje-Bougoumou First Nations (boreal Quebec, Canada) (i) to develop indicators of Indigenous landscape state, (ii) to create a typology of Indigenous hunting grounds, and (iii) to suggest guidelines for sustainable land management in Indigenous contexts. Through participatory mapping and semidirected interviews with 23 local experts, we identified factors influencing Indigenous landscape value. Using open-access data, we developed indicators to measure landscape state according to those values. We identified four types of hunting grounds with k-means clustering, based upon biophysical factors and disturbance history. Our results suggest that land management should aim to reduce differences between hunting ground states and consider the risk of rapid shifts from one state to another.

The well-being of Indigenous people relies on a deep and complex relationship with the land. The consequences of environmental changes on landscape value need to be addressed from an Indigenous perspective. To this end, the ecosystem services framework is a good starting point as it is comprehensive, bridges a number of disciplines and is acknowledged by decision-makers. However, ecosystem services face contextual limitations when used for landscape valuation in Indigenous contexts. In collaboration with two First Nations in boreal Quebec (Canada), we revisited the ecosystem services framework so that it better corresponds to Indigenous values and perspectives. We elicited value related to six landscape practices (moose and goose hunting, trapping, fishing, education and ressourcement) using semi-structured interviews and participatory mapping. Participants had to locate on a map and discuss places of high and low value for each landscape practice and for future generations. Four dimensions of landscape value emerged from thematic analysis: abundance, quality, access and experience. Landscapes contribute to the well-being of Indigenous people by sustaining livelihood, culture and identity. We developed a landscape valuation framework that is consistent with Indigenous people's relationship with the land. The framework can guide landscape management towards sustainable Indigenous landscapes.

Over the past two decades, partial harvesting has been increasingly used in boreal forests as an alternative to clearcutting to promote irregular stand structures and maintain a balance between biodiversity preservation and continued timber production. However, relatively little is still known about the silvicultural potential of partial harvesting in Canada’s boreal forest, especially in areas prone to organic matter accumulation (paludification), and most prior research has focused on biodiversity responses. In this study, we assess the effects of partial harvesting on stand development (recruitment, growth, and mortality) ten years after harvesting in previously unmanaged black spruce stands and quantify its effectiveness in reducing the impacts on ecosystem structures. Our analyses revealed that pre-harvest stand structure and site characteristics, especially initial basal area, sapling density, tree diameter, and organic layer thickness (OLT) were major factors involved in stand development ten years following these partial harvesting treatments. Depending on pre-harvest structure and site characteristics, partial harvesting can result in either an increase in post-harvest tree recruitment and growth or a loss of stand volume because of standing tree mortality. To increase the chances of partial harvesting success in ensuring an increase in decennial stand yield after harvest in black spruce forest stands, sites prone to paludification (i.e., where OLT >17 cm) should be left unharvested. This study illustrates the importance of taking into account pre-existing structure and site characteristics in the selection of management strategies to maximize the potential of partial harvesting to achieve sustainable forest management in black spruce stands.

Climate change and natural resource exploitation can affect Indigenous people’s well-being by reducing access to ecosystem services, in turn impeding transmission of traditional knowledge and causing mental health problems. We used a questionnaire based on the Environmental Distress Scale (EDS) and the Connor–Davidson Resilience Scale (CD-RISC-10) to examine the impacts of environmental changes on 251 members of four Indigenous communities in the eastern Canadian boreal forest. We also considered the potential mitigating effects of sociodemographic characteristics (i.e., age, gender, parenthood, and time spent on the land) and protective factors (i.e., health, quality of life, resilience, life on the land, life in the community, and support from family and friends). Using linear regression, model selection, and multi-model inference, we show that the felt impacts of environmental changes increased with age but were lower for participants with higher quality of life. The effect of resilience was opposite to expectations: more resilient participants felt more impacts. This could be because less resilient individuals ceased to go on the land when environmental changes exceeded a given threshold; thus, only the most resilient participants could testify to the impacts of acute changes. Further research will be needed to test this hypothesis.

Local people and scientists both hold ecological knowledge, respectively stemming from prolonged day-to-day contact with the environment and from systematic inquiry based on the scientific method. As the complementarity between scientific ecological knowledge (SEK) and local ecological knowledge (LEK) is increasingly acknowledged, LEK is starting to be involved in all branches of ecology, including ecological modeling. However, the integration of both knowledge types into ecological models raises methodological challenges, among which (1) consistency between the degree of LEK involvement and modeling objectives, (2) combination of concepts and methods from natural and social sciences, (3) reliability of the data collection process, and (4) model accuracy. We analyzed how 23 published studies dealt with those issues. We observed LEK reaches its full potential when involved at all steps of the research process. The validity of a modeling exercise is enhanced by an interdisciplinary approach and is jeopardized when LEK elicitation lacks rigor. Bayesian networks and fuzzy rule-based models are well suited to include LEK.

Severe crown fires are determining disturbances for the composition and structure of boreal forests in North America. Fire cycle (FC) associations with continental climate gradients are well known, but smaller scale controls remain poorly documented. Using a time since fire map (time scale of 300 years), the study aims to assess the relative contributions of local and regional controls on FC and to describe the relationship between FC heterogeneity and vegetation patterns. The study area, located in boreal eastern North America, was partitioned into watersheds according to five scales going from local (3 km2) to landscape (2800 km2) scales. Using survival analysis, we observed that dry surficial deposits and hydrography density better predict FC when measured at the local scale, while terrain complexity and slope position perform better when measured at the middle and landscape scales. The most parsimonious model was selected according to the Akaike information criterion to predict FC throughout the study area. We detected two FC zones, one short (159 years) and one long (303 years), with specific age structures and tree compositions. We argue that the local heterogeneity of the fire regime contributes to ecosystem diversity and must be considered in ecosystem management.

La dynamique de la forêt boréale est étroitement liée à ses régimes de perturbations, principalement les feux de forêts. Ils y initient un processus de succession secondaire et limitent les assemblages de végétation à des espèces qui y sont adaptées. L'aménagement forestier, qui s'est ajouté aux feux comme agent de perturbation, altère aussi les paysages forestiers et soulève des enjeux quant à la durabilité de la ressource et au maintien de la diversité. Une approche écosystèmique de l'aménagement propose de réduire l'écart entre les paysages naturels et aménagés afin d'assurer à la fois un apport ligneux durable et le maintien d'écosystèmes sains et résilients. Cette approche nécessite des connaissances scientifiques sur le fonctionnement et la variabilité naturelle de la forêt. Dans cette optique, le projet de maîtrise présenté dans ce mémoire avait pour objectif d'étudier le régime historique des feux et la dynamique forestière de la pessière à mousses au nord du Lac St-Jean. Le paysage étudié revêt un intérêt particulier du fait qu'il se situe à la frontière entre des zones contrastées par leurs fréquences de feu; élevée à l'ouest et modérée à l'est. La stratégie adoptée repose sur la reconstitution d'une carte du temps depuis feu à partir de données d'archives, de photos aériennes anciennes et d'analyses dendrochronologiques. Cette carte a ensuite été échantillonnée afin d'y quantifier la fréquence historique des feux et de reconstituer une chronoséquence qui relate les changements de la végétation en fonction du temps écoulé depuis le dernier feu. Le premier chapitre a pour objectif de décrire l'historique des feux des 300 dernières années afin d'en déduire la proportion et la distribution des vieilles forêts. La carte du temps depuis feu soumise à une analyse de survie (régression de Cox) a permis de calculer un cycle de feu de 247 ans pour la période 1734-2009. La majorité de l'aire brûlée était attribuable à des feux de plus de 10 000 ha, avec une taille moyenne de 10 113 ha. Une modélisation de la distribution des classes d'âge dans le paysage à partir du cycle de feu indique qu'au cours des 275 dernières années, les vieilles forêts ont occupé en moyenne 55% du paysage et formaient des mass ifs de centaines de km2. Des stratégies et cibles d'aménagement écosystémique sont proposées à la lumière de ces nouvelles connaissances. Le second chapitre, plus ancré dans l'écologie fondamentale, porte sur le régime des feux et la dynamique de la végétation. L'objectif était de distinguer l'importance relative des facteurs environnementaux, successionnels et relatifs au régime des feux pour la composition et la structure du couvert forestier. La variabilité du risque de feu en fonction des facteurs environnementaux a été étudiée par des analyses de survie. Celles-ci ont permis de calculer un cycle de feu historique de 299 ans pour les tills mésiques et hydriques et pour les dépôts organiques (65% du paysage). Un cycle de feu historique de 115 ans est plutôt associé aux dépôts secs et aux tills xériques (35% du paysage). En parallèle, la composition du couvert forestier a été décrite d'après l'abondance relative des espèces dans la canopée puis superposée à la carte des feux afin de reconstituer une chronoséquence. L'épinette noire est dominante sur l'ensemble du territoire à tous les stades de la succession. Le pin gris est présent en début de succession (70-100 ans après feu) sur les sols de texture grossière. L'abondance relative du sapin baumier est croissante avec le temps depuis feu mais est limitée par l'épaisseur de la couche organique et les pentes faibles. Nos résultats indiquent que la configuration spatiale particulière des dépôts secs et bien drainés dans les vallées des rivières permet une variabilité de la fréquence des feux à l'intérieur du paysage. Cette complexité se traduit en une diversité d'assemblages de végétation, certains typiques des fréquences de feux modérées, d'autres des fréquences de feux élevées. Les résultats issus de cette recherche ont permis d'accroître la compréhension du régime des feux, de la dynamique, de la végétation et de l'écologie du paysage de la forêt boréale. Les nouvelles connaissances pourront servir d'assise scientifique à l'implantation de l'aménagement écosystémique au nord du Lac St-Jean.

Boreal forest management in Eastern Canada has caused depletion and fragmentation of oldgrowth ecosystems, with growing impacts on the associated biodiversity. To mitigate impacts of management while maintaining timber supplies, ecosystem management aims to narrow the gap between natural and managed landscapes. Our study describes the fire history and associated natural old-growth forest proportions and distribution of a 5000 km2 area located in the black spruce-feather moss forest of central Quebec. We reconstructed a stand-origin map using archival data, aerial photos and dendrochronology. According to survival analysis (Cox hazard model), the mean fire cycle length was 247 years for the 1734–2009 period. Age-class distribution modelling showed that old-growth forests were present on an average of 55% of the landscape over the last 275 years. The mean fire size was 10 113 ha, while most of the burned area was attributable to fires larger than 10 000 ha, leading to old-growth agglomerations of hundreds of square kilometres. In regards to our findings, we propose ecosystem management targets and strategies to preserve forest diversity and resilience.