This study aimed at developing allometric equations for the estimation of aboveground biomass of black willow and eastern cottonwood and determine biomass production by these species under several planting spacing and harvest frequency combinations. Logarithmic model with dbh and tree height was the best fitting model for individual tree aboveground biomass estimation of both species. At area level, logarithmic models with stand age, dominant height, and planting density produced the best results. Mixed-effects modeling showed statistically significant effects of harvest frequency for eastern cottonwood but not for black willow. Overall, we conclude that, biomass production of black willow and eastern cottonwood would play a critical role in the fulfillment of the wood energy demands and biomass yields can be enhanced by considering management factors during plantation. These findings will be useful to forest owners in Lower Mississippi Alluvial Valley for estimating biomass without destructive sampling and have optimal biomass production.

The thesis analyzes the conditions for biogas in the Swedish transport sector. Biogas can contribute to the achievement of Sweden’s ambitious targets of decreased emissions of greenhouse gases and an increased share of renewables in the transport sector, a sector that encompasses the major challenges in the phase-out of fossil fuels. Biogas development has stagnated during recent years and there are several factors that have contributed to this. The use of biogas in transport has developed in niches strongly affected by policy instruments and in this thesis, the progress is understood as a policy-driven systemic transition. Biogas has (started to) become established at the regime level and has begun to replace fossil fuels. The major obstacles for continued biogas development are found to be the stagnated vehicle gas demand, the low predictability of Swedish policy instruments, and electric car development. Moreover, the current prolonged period of low oil prices has also contributed to a lack of top-down pressure. A large share of the cheap and easily accessible feedstock for conventional biogas production is already utilized and an increased use of vehicle gas could enable a commercial introduction of forest-derived methane. However, the technologies to produce forest-derived methane are still not commercial, although there are industrial actors with technological know-how. Future biogas development depends on how the policy framework develops. Policy makers should consider the dynamics of biogas as a young sociotechnical system where different system fronts develop at a varying pace. Currently the demand side is lagging behind. However, it is necessary to maintain predictable policy support throughout the entire biogas value chain, since the system fronts that lag can vary over time. The low predictability of Swedish policy instruments indicates that policy makers should exercise care in their design to create a more robust policy framework moving forward. / <p>QC 20170508</p>

Afin de répondre à la diversification des objectifs de la filière laitière (ex. efficacité alimentaire, santé et longévité des animaux, etc.), et ceci dans un contexte de forte volatilité des prix du lait et des intrants, la quantification des réponses multiples aux changements de régimes alimentaires représente un intérêt afin d’aider les producteurs laitiers à optimiser la ration des animaux. Le principal objectif de ce travail a consisté à développer et évaluer un modèle de prédiction des réponses de l’ingestion, de la quantité et composition du lait aux changements de régimes alimentaires chez la vache laitière. Une méta-analyse a ainsi été appliquée sur une grande base de données de la littérature afin de quantifier la réponse de l’ingestion aux régimes, et les réponses laitières (quantité totale, sécrétion des composants du lait et composition du lait) aux changements d’énergie nette (UFL) et protéines métabolisables (PDI) de la ration. Un élément clé dans le développement de ces équations de réponses était qu’elles soient applicables à travers différent potentiel laitier. Ceci a pu être atteint en exprimant les apports PDI et UFL par rapport à une situation nutritionnel pivot, qui correspond à une efficacité d’utilisation des PDI de 67% et une efficacité d’utilisation des UFL par lait de 100% (équivalente à un bilan énergétique nul). Construite à partir des efficacités PDI et UFL, une approche a été proposée pour estimer les apports PDI et UFL à la situation pivot, à partir desquels les équations de réponses peuvent s’appliquer. Evalué sur deux jeux de données indépendants, cette approche a permis de prédire les réponses de production laitière, productions de matières grasses, lactose et protéines du lait aux changements d’apports PDI et UFL avec une bonne précision pour des rations considérablement différentes, et à travers différents stades de lactation. Dans un autre modèle, les effets du stade physiologique (stade de lactation, stade de gestation, croissance) sur les performances animal, i.e. production laitière, productions de matières grasses, lactose et protéines du lait, changement de composition corporelle et ingestion, ont été quantifiés à travers des animaux de potentiel laitier différent. Il a été constaté que la structure du modèle était adéquate pour simuler les performances de différentes races laitières (Holstein, Rouge Danoise et Jersiaise). Afin de prédire les conséquences d’un changement alimentaire sur le long terme, les équations de réponses, centrées sur la situation nutritionnel pivot, ont été intégrées au sein du modèle dynamique. Cette intégration a pu se faire en appliquant le concept du pivot au modèle dynamique afin d’obtenir des courbes pivot, à partir desquelles les lois de réponses s’appliquent. Le modèle construit est le premier à intégrer les deux grands types de régulation biologique (homéostase et l’homéorhèse) chez la vaches laitière permettant de prédire les performances animales à partir d’une définition précise du potentiel laitier. / In order to better cope with the increasing diversity of objective in dairy production (e.g. feed efficiency, animal health, animal longevity, etc.) in a context of high volatility of feed and milk prices, quantification of animal’s multiple responses to dietary changes is of particular interest to help dairy farmers in optimizing the diet. The main aim of the present study was to develop and evaluate a model to predict the responses in dry-matter intake, milk yield, milk component yields and contents to changes in dietary composition in dairy cows. A meta-analysis of the literature was conducted to quantify dry-matter intake response to changes in diet composition, and milk responses (yield, milk component yields and milk composition) to changes in dietary net energy (NEL) and metabolizable protein (MP) in dairy cows. A key point in the development of these response equations was that they could be apply on animals of varying production potential. This was achieved by expressing MP and NEL supply relative to a pivot nutritional status, defined as the supply of MP and NEL resulting to MP efficiency of 0.67 and NEL efficiency of 1. Based on MP and NEL efficiency, an approach was proposed to estimate the pivot MP and NEL supplies, around which the response equations can be applied. Evaluated with two independent datasets, this approach predicted milk yield and milk component yields responses to change in MP and NEL supply with a good accuracy for diets that are substantially different, and across all stages of lactation. In another model, the effect of physiological status (lactation stage, gestation, growth) on animal performance, i.e. milk yield, milk component yields, body composition change and dry-matter intake, were quantified across a range of animal potential. It was found that the model structure was adequate to simulate performance of different dairy breeds (Holstein, Danish Red and Jersey). To predict the long-term consequences of a dietary change, response equations, centred on the pivot nutritional status, were integrated into the dynamic model. This integration has been possible by applying the pivot concept into the dynamic model. This way, lactation pivot curves were calculated, from which response equations are applied. The model built is the first to integrate the two major biological regulations (homeostasis and homeorhesis) in dairy cows that predicts animal performance using a precise definition of milk potential.

Acid mine drainage (AMD) is a worldwide environmental problem associated with the mining wastes, generated from active and inactive mining sites from mineral processing activities. AMD is defined as the drainage that occurs as a result of oxidation of sulphide minerals/wastes/tailings when exposed to air and water in the presence of chemolithotrophs namely the Acidithiobacillus sp. AMD is characterised by low pH and increased acidity due to elevated heavy metals and sulphate concentration. The acid production potential was carried out for sulphide minerals such as pyrite and chalcopyrite and copper tailings sample in the absence and presence of bacteria namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Acidity was generated in all the cases due to the oxidation of the mineral samples. The oxidation was found to occur at a higher rate in the presence of the bacteria compared to the control samples. Bioremediation experiments were conducted on acid mine water collected from the Ingaldahl Mines, Chitradurga, Karnataka, India, using organic and inorganic substrates. In the experiments with rice husk, complete removal of metal ions from the acid mine water was achieved with an attendant increase in the pH of the acid mine water from 2.3 to 5.5. About 21% of sulphate could be removed using Dsm. nigrificans from acid mine water pretreated with rice husk at pH 5.5 and this was further increased to 40% by the supplementation of organic components. The rice husk filtrate was found to serve as a good growth medium for Dsm. nigrificans. About 96 % of Fe, 75 % of Zn, 92 % of Cu and 41 % of sulphate removal was achieved from the acid mine water of pH 2.4 with a concomitant increase in the pH value by two units after interaction with the tree bark. About 56 % and 71 % of sulphate reduction could be achieved at initial pH values of 4.1 and 5.5 respectively of the acid mine water pretreated with E. tereticornis (Sm) bark, after inoculation with Dsm. nigrificans. The complete removal of Fe2+ and Fe3+, 80% of Zn, 83% of Cu and 62% of sulphate could be removed from acid mine water using fly ash as the substrate with an increase in pH of acid mine water from 2.3 to 7. About 68% of sulphate reduction at pH 6.8 could be achieved in acid mine water pretreated with fly ash in the presence of Dsm. nigrificans. With red mud as the substrate, complete removal of all the metal ions namely Fe2+, Fe3+, Zn, and Cu from acid mine water was achieved with a concomitant increase in the pH from 2.3 to 8. The sulphate reduction was increased to about 51% at pH 7.2 when the acid mine water pretreated with red mud was inoculated with Dsm. nigrificans. The adsorption experiments carried out on the acid mine water using either organic or inorganic substrates indicated that the free energy of adsorption was negative for all the chosen metal ions attesting to favorable interaction. The adsorption isotherms of the metal ions for rice husk exhibited Langmuirian behaviour, while those for the other substrates adhered to both Langmuir and Freundlich relationships. The adsorption process was found to be endothermic in nature for rice husk, fly ash and red mud. On the contrary, the adsorption onto tree bark showed exothermic behaviour. The adsorption kinetics of the metal ions onto the various substrates adhered to the first order Lagergren equation. The metal uptake processes by the organic and inorganic substrates chosen for this study involve ionic, chemical and physical forces of adsorption. The different types of functional groups present on the surface of the substrates such as carboxyl, hydroxyl and carbonyl, as revealed by FTIR spectroscopic studies, partake in metal binding. The metal ions will also be adsorbed by complexing with the negatively charged reaction sites on the substrate surfaces. Furthermore, the complex solution chemistry of the metals as a function of pH has also to be taken into consideration. The mechanism of sulphate reduction by Dsm. nigrificans in the presence of organic carbon can be illustrated as: 2CH2O + SO42- + 2H+  2CO2 + 2H2O + H2S M2 + H2S  MS  + 2H+ where, CH2O represents the organic matter and M represents the metal ion.