Hennebelle2020

Référence

Hennebelle, A. (2020) Joindre le passé et le présent par les études paléoécologiques dans un contexte d’aménagement écosystémique de la forêt boréale du Québec. Thèse de doctorat, Université de Montréal. (URL )

Résumé

In the boreal forests, current objectives in terms of protection and management of ecosystemsare facing uncertainties due to climate change. Indeed, ongoing and future climate change haveand will have noticeable consequences on boreal ecosystems composition, structure and dynamic(Figure I.1). Ecosystem dynamic is also influenced by natural disturbances such as fire, insectoutbreaks and windthrows for which regimes (occurrence, surface, severity...) will be modified byclimate change. Moreover, direct and indirect impacts of human activities will keep on increasingand interfering with ecosystems functioning. Thus, knowing how the resistance and resilience ofecosystems will be affected is challenging. By the same token, protecting ecosystems integrityand sustaining the usages we have of them raise concerns. Many efforts have been put in placeas an answer to these questions such as in Québec with the establishment of an ecosystem basedmanagement of forest which aims at reducing the gap between natural and managed forests. Nevertheless,one should not neglect that ecosystems are dynamic entities with resistance and resiliencecapacities (adaptation) in response to environmental constraints (climate, disturbances...). Theseinteractions are occurring since the retreat of the glacier that was covering Québec during thelast Ice Age. Quickly, ecosystems differentiated and followed their own path until reaching theircurrent state. In order to protect the ecosystems we need to understand their current state andtheir long-term dynamic thus asking the question of the methods available to access ecologicalhistory of the ecosystems.Methods can be applied following spatial and temporal scales often considered as antagonistics(Figure I.2). Indeed, temporal scale is often replaced by spatial scale such as for extensive inventories.On the contrary, the description of long-term ecosystem dynamic can be done at theexpense of spatial scale such as in paleoecology. The longer the temporal scale is, the less the dataare abundant and the more reconstructions rely on indirect indicators of (e.g: fire, vegetation, ...)which presence and abundance must be described via proxies as pollen or charcoal (Figure I.2).The objective of this thesis is to reconcile the two scales, temporal scale and spatialscale, in paleoecological studies and contemporary ecological studies with the Quebec westernspruce-feathermoss subdomain (PMO) as study area. First, the current ecosystem diversity and itspluri-millennial history have been studied and support the establishment of low scale ecosystemicmanagement targets. The Holocene reconstructions of vegetation and fire from the first chapterhighlighted the challenges of multi-proxy analyses. These difficulties are mostly due to the lack13of knowledge concerning the influence of taphonomic processes in the recording of bio-proxies ina sedimentary archive. The two other chapters composing this thesis helped to understand thelinks existing between the ecosystems and the bio-proxy signals they generate in order to developmethodological tools to facilitate their interpretation. Overall, these tools will allow us to betterunderstand long-term dynamics of boreal forest ecosystems in the PMO.

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@PHDTHESIS { Hennebelle2020,
    TITLE = { Joindre le passé et le présent par les études paléoécologiques dans un contexte d’aménagement écosystémique de la forêt boréale du Québec },
    AUTHOR = { Hennebelle, A. },
    SCHOOL = { Université de Montréal },
    YEAR = { 2020 },
    NOTE = { CEFTMS, Blarquez, O. and Grondin, P. },
    ABSTRACT = { In the boreal forests, current objectives in terms of protection and management of ecosystemsare facing uncertainties due to climate change. Indeed, ongoing and future climate change haveand will have noticeable consequences on boreal ecosystems composition, structure and dynamic(Figure I.1). Ecosystem dynamic is also influenced by natural disturbances such as fire, insectoutbreaks and windthrows for which regimes (occurrence, surface, severity...) will be modified byclimate change. Moreover, direct and indirect impacts of human activities will keep on increasingand interfering with ecosystems functioning. Thus, knowing how the resistance and resilience ofecosystems will be affected is challenging. By the same token, protecting ecosystems integrityand sustaining the usages we have of them raise concerns. Many efforts have been put in placeas an answer to these questions such as in Québec with the establishment of an ecosystem basedmanagement of forest which aims at reducing the gap between natural and managed forests. Nevertheless,one should not neglect that ecosystems are dynamic entities with resistance and resiliencecapacities (adaptation) in response to environmental constraints (climate, disturbances...). Theseinteractions are occurring since the retreat of the glacier that was covering Québec during thelast Ice Age. Quickly, ecosystems differentiated and followed their own path until reaching theircurrent state. In order to protect the ecosystems we need to understand their current state andtheir long-term dynamic thus asking the question of the methods available to access ecologicalhistory of the ecosystems.Methods can be applied following spatial and temporal scales often considered as antagonistics(Figure I.2). Indeed, temporal scale is often replaced by spatial scale such as for extensive inventories.On the contrary, the description of long-term ecosystem dynamic can be done at theexpense of spatial scale such as in paleoecology. The longer the temporal scale is, the less the dataare abundant and the more reconstructions rely on indirect indicators of (e.g: fire, vegetation, ...)which presence and abundance must be described via proxies as pollen or charcoal (Figure I.2).The objective of this thesis is to reconcile the two scales, temporal scale and spatialscale, in paleoecological studies and contemporary ecological studies with the Quebec westernspruce-feathermoss subdomain (PMO) as study area. First, the current ecosystem diversity and itspluri-millennial history have been studied and support the establishment of low scale ecosystemicmanagement targets. The Holocene reconstructions of vegetation and fire from the first chapterhighlighted the challenges of multi-proxy analyses. These difficulties are mostly due to the lack13of knowledge concerning the influence of taphonomic processes in the recording of bio-proxies ina sedimentary archive. The two other chapters composing this thesis helped to understand thelinks existing between the ecosystems and the bio-proxy signals they generate in order to developmethodological tools to facilitate their interpretation. Overall, these tools will allow us to betterunderstand long-term dynamics of boreal forest ecosystems in the PMO. },
    URL = { https://papyrus.bib.umontreal.ca/xmlui/handle/1866/25245 },
    TIMESTAMP = { 2021-09-09 },
}

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