The land-atmospheric exchanges of carbon dioxide (CO2) and methane (CH4) are major drivers of global warming and climatic changes. The greenhouse gas (GHG) fluxes indicate the dynamics and potential storage of carbon in terrestrial and wetland ecosystems. Appropriate modeling and prediction tools can provide a quantitative understanding and valuable insights into the ecosystem carbon dynamics, while aiding the development of engineering and management strategies to limit emissions of GHGs and enhance carbon sequestration. This dissertation focuses on the development of data-analytics tools and engineering models by employing a range of empirical and semi-mechanistic approaches to robustly predict ecosystem GHG fluxes at variable scales. Scaling-based empirical models were developed by using an extended stochastic harmonic analysis algorithm to achieve spatiotemporally robust predictions of the diurnal cycles of net ecosystem exchange (NEE). A single set of model parameters representing different days/sites successfully estimated the diurnal NEE cycles for various ecosystems. A systematic data-analytics framework was then developed to determine the mechanistic, relative linkages of various climatic and environmental drivers with the GHG fluxes. The analytics, involving big data for diverse ecosystems of the AmeriFLUX network, revealed robust latent patterns: a strong control of radiation-energy variables, a moderate control of temperature-hydrology variables, and a relatively weak control of aerodynamic variables on the terrestrial CO2 fluxes. The data-analytics framework was then employed to determine the relative controls of different climatic, biogeochemical and ecological drivers on CO2 and CH4 fluxes from coastal wetlands. The knowledge was leveraged to develop nonlinear, predictive models of GHG fluxes using a small set of environmental variables. The models were presented in an Excel spreadsheet as an ecological engineering tool to estimate and predict the net ecosystem carbon balance of the wetland ecosystems. The research also investigated the emergent biogeochemical-ecological similitude and scaling laws of wetland GHG fluxes by employing dimensional analysis from fluid mechanics. Two environmental regimes were found to govern the wetland GHG fluxes. The discovered similitude and scaling laws can guide the development of data-based mechanistic models to robustly predict wetland GHG fluxes under a changing climate and environment.

Les besoins en terre végétale pour l’aménagement d’espaces verts urbains induisent un prélèvement de sols agricoles ou naturels. D’autre part, des volumes considérables d’horizons profonds excavés lors de la construction de bâtiments sont mis en décharge en périphérie des villes, avec un impact sur l’environnement. Le recyclage de ces déchets inertes pour la construction de sols des espaces verts apparaît comme une solution prometteuse. Il est toutefois nécessaire de s’assurer que ces Technosols construits peuvent accueillir une diversité végétale et animale pour délivrer des services écosystémiques, comme propose de le faire ce travail de thèse. La composition des mélanges de matériaux (horizons profonds, compost de déchets verts, béton concassé) a été manipulée dans une expérimentation de 4000 m² en collaboration avec l’entreprise ECT et le CD 93. Un suivi de quatre ans a montré que le compost utilisé était responsable de la mort de certains arbres, mais qu’associé au béton, il augmentait fortement leur vitesse de croissance et de colonisation par la macrofaune. En usage prairial, l’ajout de compost a augmenté la production de biomasse et modifié l’assemblage de la communauté végétale, en favorisant les espèces compétitives, mais pas de la macrofaune. Dans une expérience en mésocosmes visant à étudier le lien entre diversité végétale et productivité, une complémentarité entre espèces a été observée pour une des trois communautés, à un niveau de fertilité intermédiaire. Il est donc possible d’améliorer la productivité primaire de nouveaux écosystèmes en manipulant la composition des mélanges de matériaux tout en évitant la dominance de certaines espèces, afin de conserver des communautés diversifiées / Topsoil requirements for the development of urban green spaces induce a harvest of agricultural or natural soils. On the other hand, huge volumes of deep horizons excavated during the construction of buildings are dumped on the outskirts of cities, with an impact on the environment. The recycling of these inert wastes for the construction of soils for green spaces appears as a promising solution. However, it is necessary to ensure that these constructed Technosols are suitable for plant and animal diversity, and can deliver ecosystem services, as proposed by this thesis. The composition of the material mixes (deep horizons, urban green waste compost, crushed concrete) was manipulated in a 4000 m² experiment in collaboration with the company ECT and CD 93. A four-year monitoring showed that the compost used was responsible for the death of some trees, but associated with concrete, it greatly increased their growth rate and macrofaunal colonization. In the meadow land use, the addition of compost increased biomass production and altered the assemblage of the plant community, favoring competitive species, but no effect on macrofauna assemblage was observed. In a mesocosm experiment aiming at studying the link between plant diversity and productivity, complementarity between species was observed for one of the three communities, at an intermediate level of fertility. It is therefore possible to improve the primary productivity of new ecosystems by manipulating the composition of the mixtures of materials while avoiding the dominance of certain species, in order to preserve diversified communities

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River-floodplain connectivity is defined as the water mediated transfer of materials and energy between a river or stream and its adjacent floodplain. It is generally accepted that restoring and/or enhancing river-floodplain connectivity can reduce the downstream flux of reactive solutes such as nitrogen (N) and phosphorus (P) and thus improve downstream water quality. However, there is little scientific literature to guide ecological engineering efforts which optimize river-floodplain connectivity for solute retention. Therefore, the aim of my dissertation research was to examine feedbacks between inundation hydrology and floodplain biogeochemistry, with an emphasis on analyzing variation experienced along the river continuum and the cumulative effects of river-floodplain connectivity at the basin scale. This was completed through four independent investigations. Field sites ranged from the Atchafalaya River Basin, the largest river-floodplain system in the continental US, to the floodplain of a recently restored headwater stream in Appalachia. We also developed a method to examine river-floodplain connectivity across large- river networks and applied that methodology to US stream network. Largely, our results highlight the role floodwater residence time distributions play in floodplain biogeochemistry. In headwater streams, residence times restrict redox dependent processes (e.g. denitrification) and downstream flushing of reactive solutes is the dominant process. However, in large-river floodplains, redox dependent processes can become solute limited because of prolonged residence times and hydrologic isolation. In these floodplains, the dominant process is often autochthonous solute accumulation. Further, results from our modeling study suggest large-river floodplains have a greater impact on downstream water quality than floodplains associated with smaller streams, even when considering cumulative effects across the entire river network. / Ph. D.

Dans le but d'évaluer la possibilité de mise en place une ingénierie écologique des processus microbiens de la digestion anaérobie dans les bioprocédés, différents leviers environnementaux ont été appliqués à des digesteurs de cellulose. Le premier levier étudié, de nature physico-chimique, était la température. Le deuxième faisait appel à une adaptation préalable d'une biomasse complexe par incubation avec des molécules simples avant mise en présence de cellulose. Le dernier consistait en la co-inoculation de diverses biomasses exogènes avec une boue anaérobie. Les conséquences des perturbations apportées par ces leviers sur les dynamiques métaboliques et écologiques de bioréacteurs anaérobies dégradant de la cellulose ont été évaluées. Différents indicateurs physico-chimiques ont été utilisés pour caractériser la dégradation de la cellulose (production de molécules intermédiaires, production de gaz, etc.). Les outils de la biologie moléculaire ont permis de caractériser les dynamiques microbiennes à l'échelle des communautés (par fingerprinting ARISA) ou des individus (par pyroséquençage de l'ADNr 16S). L'utilisation d'isotopes stables (cellulose marquée 13C), a permis de réaliser un traçage précis des flux de matières (intermédiaires de dégradation de la cellulose enrichis en 13C) et des microorganismes impliqués dans la chaîne de dégradation de la cellulose (groupes microbiens fonctionnels identifiés par la technique de « stable isotope probing »). Les expériences de changements de température ont montrél'influence importante de ce paramètre sur les communautés microbiennes, en particulier les archées. Elles ont mis en évidence le caractère asymétrique de l'effet de la température sur les communautés microbiennes et les conséquences irréversibles du passage par les conditions thermophiles. Ces propriétés ouvrent des perspectives intéressantes pour exploiter les chocs de température afin de modifier les propriétés de la biomasse. L'expérience de fonctionnalisation de la biomasse à l'aide de quatre molécules simples (acide propionique, acide butyrique, glucose et cellobiose) montre qu'un modelage des populations microbiennes par préadaptation est possible. Une fois en contact avec la cellulose, les biomasses fonctionnalisées génèrent des schémas de dégradation et des structures de communautés qui se répartissent de manière inattendue en deux catégories seulement. Ce résultat suggère qu'il est possible d'orienter les états d'équilibre d'une communauté microbienne complexe par préadaptation fonctionnelle. Enfin, des expériences de co-inoculation ont mis en avant la difficulté d'exploiter directement les propriétés enzymatiques de flores cellulolytiques performantes mais également les possibilités de modifier les équilibres de diversité au sein de la biomasse du bioprocédé. Ces expériences suggèrent qu'un paramètre tel que la diversité de la communauté d'un bioprocédé pourrait être manipulé par bioaugmentation. Ce travail démontre que nous disposons d'ores et déjà d'un certain nombre d'outils pour élaborer une ingénierie écologique des bioprocédés à travers une nouvelle démarche de gestion qui se place à l'échelle de l'écosystème microbien et des services associés. / In order to evaluate the possibility of establishing an ecological engineering of microbial processes of anaerobic digestion in bioprocesses, different environmental levers were applied to cellulose digesters. The first lever studied was temperature. The second involved preadaptation of a complex biomass by incubation with simple molecules, before addition of cellulose. The third lever consisted in co-inoculating various exogenous biomasses with anaerobic sludge. The consequences of these levers on metabolic and ecological dynamics of cellulose-degrading anaerobic bioreactors were evaluated. Different physicochemical indicators were used to characterize cellulose degradation (intermediate production, gas production, etc.). Molecular biology tools enabled the characterization of microbial dynamics at the community level (ARISA fingerprinting) or individual level (16S rDNA pyrosequencing ). The use of stable isotopes (13C-labeled cellulose) enabled the accurate tracing of both material flows (13C enriched cellulose intermediates) and microorganisms involved in the cellulose degradation chain (functional microbial groups were identified by "stable isotope probing" technique). Temperature changes showed the significant influence of this parameter on microbial communities, especially Archaea. The asymmetric nature of temperature effect on microbial communities, and the irreversible consequences of incubation in thermophilic conditions were highlighted. These properties open interesting perspectives for the use of temperature shocks to modify biomass properties. A biomass functionalization experiment was performed with simple molecules (propionic acid, butyric acid, glucose and cellobiose). It showed that shaping microbial communities through substrate adaptation was possible. Once in contact with the cellulose, functionalized biomasses generated patterns and structures of degradation communities who unexpectedly formed two categories only. This result suggests that it is possible to direct the equilibrium states of a complex microbial community by functional preadaptation. Finally, co-inoculation experiments highlighted the difficulty of directly exploiting the enzymatic properties of efficient cellulolytic flora. But, they also highlighted the possibility of changing biomass diversity balance in bioprocesses. Thus these experiments suggest that a parameter such as community diversity can be manipulated by bioaugmentation in bioprocesses. This work demonstrates that several tools are available to develop an ecological engineering of bioprocesses, through a new management approach at the microbial ecosystem (and related services) level.

Human production needs are met through the use of modern technology that is increasingly recognised as a threat to the planetary ecosystem and social sub-system. In light of this recognition, there is evidence that a planned transition towards more sustainable technological infrastructure is occurring across various production sectors. This change is often associated with re-orientating technology based on the concept of sustainable development and national-level strategies such as <i>ecological modernisation</i>, which prescribes phasing-out environmentally malignant conventional technology for cleaner post-industrial solutions. There is evidence, however, that a transition towards cleaner technological options is occurring at the local level. In southern Ontario, Canada ecological technology (<i>ecotechnology</i>) has been adopted in small-scale agricultural and educational facilities for the management of manure and domestic sewage. Ecotechnology is designed to meet human production requirements and to restore the environment through combining natural systems and engineered components to achieve cleaner production. Two types of ecotechnologies were investigated during this research: <i>constructed treatment wetlands</i> for the management of manure and <i>greenhouse-based biological technologies</i> for the management of domestic sewage. These options are novel and can be expected to encounter barriers resulting from a <i>selection environment</i> favouring pre-existing technological options that have previously become established. The overall objective of the research was <i>to identify key factors both driving and constraining the adoption and implementation of the ecotechnology</i> across four case studies. This objective was accomplished through employing a qualitative, collective case study approach. The case studies revealed the motivation behind the adoption of the ecotechnology arose from the environmental values of users and formed the basis for rejecting the conventional options because they were not viewed as capable of improving the environment. However, the ecotechnology also exceeded user's aesthetic and operational level expectations. Barriers to the implementation of ecotechnology were also identified. The investigation revealed the existence of a <i>perspective-gap</i> between the ecological engineering science and traditional engineering science, which constrained implementation of the ecotechnology. Skepticism was found to arise due to the unique performance parameters and <i>soft</i> operational characteristics of ecotechnology, which contrast the <i>hard</i> technological fixes that are familiar to traditional engineering science. This perspective-gap may account for the institutional inertia, which became clear after the 1996 provincial budget reductions decreased the level of support for research and environmental technology development programs in Ontario. These reductions also devolved authority for small-scale wastewater treatment to the municipal level where lack of technical expertise and reliance on standardised regulations has constrained the development of alternatives. Constructive technology assessment suggests that the development of technology must be guided in cooperative <i>social learning</i> processes capable of reflecting the needs and values of stakeholders in order to achieve beneficial social and technological change. Evidence from the case studies revealed that a significant amount of capacity was developed when stakeholders collaborated and legitimated the <i>social experiments</i> where the ecotechnology was applied. These experiments demonstrate the significance of creating settings where users, technology proponents and provincial and local approval agents can collaborate. Through collaboration, social learning can be facilitated during the development of alternative technological solutions that may be congruent with ecological modernisation and the re-orientation of technology towards options that are ecologically-oriented.

Human production needs are met through the use of modern technology that is increasingly recognised as a threat to the planetary ecosystem and social sub-system. In light of this recognition, there is evidence that a planned transition towards more sustainable technological infrastructure is occurring across various production sectors. This change is often associated with re-orientating technology based on the concept of sustainable development and national-level strategies such as <i>ecological modernisation</i>, which prescribes phasing-out environmentally malignant conventional technology for cleaner post-industrial solutions. There is evidence, however, that a transition towards cleaner technological options is occurring at the local level. In southern Ontario, Canada ecological technology (<i>ecotechnology</i>) has been adopted in small-scale agricultural and educational facilities for the management of manure and domestic sewage. Ecotechnology is designed to meet human production requirements and to restore the environment through combining natural systems and engineered components to achieve cleaner production. Two types of ecotechnologies were investigated during this research: <i>constructed treatment wetlands</i> for the management of manure and <i>greenhouse-based biological technologies</i> for the management of domestic sewage. These options are novel and can be expected to encounter barriers resulting from a <i>selection environment</i> favouring pre-existing technological options that have previously become established. The overall objective of the research was <i>to identify key factors both driving and constraining the adoption and implementation of the ecotechnology</i> across four case studies. This objective was accomplished through employing a qualitative, collective case study approach. The case studies revealed the motivation behind the adoption of the ecotechnology arose from the environmental values of users and formed the basis for rejecting the conventional options because they were not viewed as capable of improving the environment. However, the ecotechnology also exceeded user's aesthetic and operational level expectations. Barriers to the implementation of ecotechnology were also identified. The investigation revealed the existence of a <i>perspective-gap</i> between the ecological engineering science and traditional engineering science, which constrained implementation of the ecotechnology. Skepticism was found to arise due to the unique performance parameters and <i>soft</i> operational characteristics of ecotechnology, which contrast the <i>hard</i> technological fixes that are familiar to traditional engineering science. This perspective-gap may account for the institutional inertia, which became clear after the 1996 provincial budget reductions decreased the level of support for research and environmental technology development programs in Ontario. These reductions also devolved authority for small-scale wastewater treatment to the municipal level where lack of technical expertise and reliance on standardised regulations has constrained the development of alternatives. Constructive technology assessment suggests that the development of technology must be guided in cooperative <i>social learning</i> processes capable of reflecting the needs and values of stakeholders in order to achieve beneficial social and technological change. Evidence from the case studies revealed that a significant amount of capacity was developed when stakeholders collaborated and legitimated the <i>social experiments</i> where the ecotechnology was applied. These experiments demonstrate the significance of creating settings where users, technology proponents and provincial and local approval agents can collaborate. Through collaboration, social learning can be facilitated during the development of alternative technological solutions that may be congruent with ecological modernisation and the re-orientation of technology towards options that are ecologically-oriented.

The care of planet Earth is the responsibility of all that inhabit it. Our environment sustains us, and choices we make can compromise the Earth's capacity to sustain life.This project explores how landscape architecture can be a tool that can aid in the process of sustaining certain systems of the Earth, while providing form and function for humans at the same time. Coupled with environmental education programming, the site design becomes the framework in which the programming is based.To sustain life, the Earth must give of its resources. It is well understood that the resources on the planet are limited. Altering systems of life support on the planet must embrace a holistic view in that all systems must be maintained, yet at the same time allow us to derive our means from them.Environmental education is a magical arena that allows for nurturing of human developmental needs by providing outlets for their social, emotional, physical, and cognitive growth. At the same time environmental education provides answers to questions that children and adults have about the environment. Landscape Design in the arena of environmental education can provide a direct link to issues of sustaining life support systems and how people learn about maintaining those systems wisely. / Department of Landscape Architecture

Sustainable development is a ubiquitously used concept referring to a vision of society centred on the principles of global responsibility, integration, inter- and intra-generational equity, precaution, participation and a long-term time horizon. It is a contested concept that regroups various sub-discourses which embody its constructive ambiguity. For sustainable development to become a decision-guiding strategy in pubic decision-making, adequate decision-supporting processes are required. This thesis reflects on the theory and on the practice of ‘sustainability assessment’ in various contexts by combining discourse analysis with a case-study approach. <p>The thesis builds on three case studies, undertaken in different –institutional, geographical, thematic and research- contexts. The three cases (situated respectively in the realm of sub-national policies; development co-operation and energy policy) allow for different approaches to sustainability assessment to be applied and analyzed. The relative novelty of sustainability assessment created room for experimental participatory approaches and provided opportunities for policy-relevant learning. Understanding how sustainability assessment contributes to a shared interpretation of sustainability, to an enhanced structuring of information and to influencing policy decisions is key to develop and apply the approach in the future. Research findings indicate that: sustainability assessment should act as a forum giving sense to the interpretational challenge of sustainability, within the boundaries set by essential sustainability principles. Participatory approaches are key in performing sustainability assessment, for both intrinsic and pragmatic reasons. Stakeholder knowledge should be combined with scientific information in real-life ‘science for sustainability’ experiments. There is no blueprint approach for developing and applying sustainability assessment. The discursive-institutional interplay determines how sustainability assessment is conceptualized and applied. Windows of opportunity for introducing and applying sustainability assessment may arise unexpectedly due to discursive and institutional convergences facilitated by the interpretational width of the sustainability concept, and these should be taken up. Sustainability assessment should be designed as a de-polarizing process, bringing the co-production of knowledge and decisions into practice. <p>The capacity of sustainable development to grasp the complexity of current societal challenges by providing a decision-guiding framework can be operationalized by sustainability assessment, which entails an increased awareness of the overlap between different areas of public policy. If sustainability assessment is to actually support decision-makers, scientifically and participatory designed beacons are needed. This is a challenge where scientists act as analysts and facilitators to help translate the intrinsically dynamic meaning of sustainability into actions. This thesis wishes to contribute to this endeavour. <p><p><p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Ce sujet de recherche vise mieux comprendre les processus de bio remédiation qui participent à la réduction des charges en polluants dans les écosystèmes aquatiques du type zones humides, en tant que question d'actualité en ingénierie écologique. L'efficacité des processus de phytoremédiation a été largement démontrée par des applications individuelles sur le sol et les sédiments. Cette thèse a pour objectif de démontrer la participation d'une population d'invertébrés dans l'efficacité de la réduction de polluants des sédiments aquatiques en combinant le processus de bioturbation avec la phytoremédiation. Les hypotheses de recherche ont été testée expérimentalement en conditions de laboratoire à l'aide d'une série de microcosmes reproduisant chacun une portion d'interface eau/ sédiments similaire aux conditions en zones humides. Dans nos expériences, la bioturbation est réalisée par une population d'oligochètes Tubificidae bien connue comme un ingénieur écologique. La phytoremédiation associée est effectuée par une plante aquatique Typha latifolia connue pour sa capacité à extraire les polluants organiques et inorganiques des sédiments par l'accumulation dans leur biomasse. L'influence de cette biodiversité sur les flux et bilan de masse de polluants modèles, a été démontré à l'aide de 2 expériences de laboratoire mettant en oeuvre des séries de microcosmes contaminées avec du Cadmium en tant que métal trace avec une concentration initiale de 20 µg.L-1, dans l'eau surnageante, et de l'atrazine marquée avec une concentration de 5 µg.g-1 de sédiment frais en tant que micropolluant organique persistant et herbicide. Les résultats de ces expériences démontrent que le bio-transport créé par la population de tubificidae ainsi que la bioremédiation sont toujours actifs en présence de contamination ce qui confirme le potentiel de dévelopement de ces organismes en ingénierie écologique. La bioadvection du sédiment et des contaminants par les tubificidae est quantifiée grâce à l'utilisation de luminophores (traceurs particulaires). [...] / The development of efficient bioremediation techniques to reduce pollutant loads in aquatic ecosystems is a challenging research question for ecological engineering. The accuracy of phytoremediation processes has been primarily demonstrated by individual applications on soils or water sediments. The present Ph.D. aims to demonstrate the interest of additional bioturbation combined to phytoremediation processes for the improvement bioremediation efficiency of aquatic sediments. This strategy benefits are tested experimentally in controlled laboratory conditions with a serie of microcosms reproducing each a portion of water/sediment interface such as in wetland areas. In our experiments, bioturbation was carried out by a conveyor-belt invertebrate population, the tubificidae oligochaetes Tubifex tubifex, well known as an active ecological engineer. The phytoremediation was conducted by the riparian plant Typha latifolia known for its ability to remove organic and inorganic pollutants from sediments by accumulation into its biomass. The experiments were managed to demonstrate the effects of this biological influence (plant and inveterbrate) on the mass balances and fluxes of one metal and one pesticide as models of pollutants. Cadmium as a heavy, inorganic and conservative metal pollutant was introduced as a pulse input in the overlying water of the contaminated microcosms, with a cadmium concentration of 20 µg.L-1 in at the initial time of the experiment that lasted one month. In a second experiment, atrazine was mixed in the whole sediment column at the initial time in order to reach a concentration of 5 µg.g-1 of fresh sediment as a source of organic micropollutant and herbicide in the microcosms. The pesticide was radiolabeled with 14C. Fluxes from water to sediment, and from sediment to plants were assessed in experimental conditions with several treatments (+/- plants, +/- bioturbation, +/- pollutants) allowing to demonstrate the effects of the biological influence. Our results indicated that the tubificids and the related bioremediation influences are still efficient under cadmium and atrazine contaminations in aquatic systems. Biotransport due to tubificids changed the distribution of cadmium across the sediment column and enhanced the pumping of cadmium from the water to surface sediment and then to the anoxic underlying sediment surrounding the plant roots. [...]