Thèses sur le sujet « Wood accumulation »

Large wood and its accumulations are poorly understood despite being an important feature in the functioning of forested river channels and floodplains. Large wood has previously been removed from rivers in order to reduce flow resistance and increase channel conveyance. However, recently there has been an appreciation of the role of large wood accumulations in creating important aquatic habitat, increasing geomorphic diversity, re-connecting river channels to their floodplains and in the development of multi-channel anastomosed river patterns. This thesis examines the role that large wood plays at a range of scales in a low-order forested stream in the New Forest, Southern England. The study river was subject to restoration measures, involving the addition of large wood to the river channel, as part of an EU LIFE III project. An empirical and Froude-scaled flume approach is taken to determine the role of large wood accumulations upon the reach-scale flow resistance values. Large wood accumulations from a variety of environments are assessed to determine the hydraulic effects of accumulations of different architecture in different environments. Field data from the study catchment is used to show the role of large wood in increasing the frequency and duration of reach-scale, floodplain inundation. Hydrological data shows the impact the restoration has upon both flood peak magnitude and flood peak travel time highlighting the potential benefits of large wood to downstream flood risk. A 2-Dimensional model is produced which simulates the effect of a range of large wood accumulations upon the inundation extent. An approach using spatial diversity metrics, widely used in ecological sciences, is conducted in an attempt to quantify the flow depth and flow velocity diversity, which can influence flow habitat diversity. Results show that large wood can initiate an anastomosing flow pattern which allows increases flow depth diversity by up to 49% and flow velocity diversity by up to 48%

The world's forests sequester roughly a quarter of anthropogenic emissions of carbon dioxide and store it in wood. Assessing this carbon sink includes quantifying annual wood production, establishing baselines, and characterizing both long-term trends and inter-annual variability. Direct measures of forest wood production are often based on measures of individual tree growth along the stem, often taken at a single height: basal height (1.3 meters). This assumes that a measurement of wood production at a single height is representative of wood production along the whole stem. In violation of this assumption, it is known that trees do accumulate wood differentially along the stem, and that this longitudinal variability can change from year to year. Few efforts have been made to describe annual longitudinal variability, and quantify the error in estimated annual whole-stem wood production related to assuming that constant wood production along the stem. In the present study, I present a stem analysis of 30 Populus grandidentata to address this. Dendrochronological techniques are used to develop three chronologies: a traditional tree-ring width chronology from basal height, a novel chronology developed from tree rings grown in the crown of the trees, and a specific volume increment chronology calculated from measured annual volume increment data. A novel taper chronology is also presented. In Chapter 2, comparisons are made between the chronologies to explore differences in inter-annual variability, and the suitability for using tree-ring data from basal height as a proxy for annual wood production. Both basal and crown tree-ring width chronologies were strongly correlated with the volume chronology (r = 0.96 and 0.88, respectively), suggesting that the basal chronology is a superior proxy for stem volume. However, a chronology of taper along the stem indicates that the reliability of either chronology to represent specific volume increment (SVI) changes over time, resulting in different common signals, especially in the last decade of this dataset. If accurately capturing the relative year-to-year changes in stem wood volume is desired, stem dissection and development of an SVI chronology is required. In Chapter 3, two models that use tree-ring data to estimate annual wood production are compared to volume measurements from the stem analysis. The two models are a site-specific allometric model of biomass, and a simplified conic model of volume. Additionally the conic model is decomposed into the three dimensions of growth along which variability exists (around the circumference, along the length of the stem, and height) to identify which dimension introduces the most error when no variability in that dimension is assumed. Relative error (RE) analysis and regression analysis show that stem analysis is superior in cases where few trees are used and accurate measures of wood increment are needed. At the population level, the allometric and conic models show different strengths. Allometric models are more accurate than the conic model (RE = -16% and -18%, respectively) and are better for carbon budgets, whereas the conic model was more precise than the allometric model (R² = 0.94 and 0.86, respectively; interquartile range = 24% and 41%, respectively) and maintains inter-annual variability, which is necessary in cross-validation efforts. Decomposition of the conic model supports previous findings that height is the second most important parameter, following diameter at breast height, in models of woody tissue growth. In Chapter 4, basal, crown and specific volume chronologies are compared to eddy covariance estimates of carbon dioxide flux between the forest and the atmosphere, including net ecosystem exchange, gross primary production and ecosystem respiration. At the University of Michigan Biological Station (UMBS), crown-grown tree-ring widths from P. grandidentata individuals are good recorders of the inter-annual variability of net ecosystem production. Coupled with other environmental information from UMBS, these records implicate defoliating insects as a previously under-appreciated modifier of stand level respiration and gross primary production. These histories of ring widths, volume and taper have unique potential to improve our understanding of how carbon is stored in and flows through forests within the terrestrial biosphere. In the face of global change, forests will experience new stressors, and changes in frequency of known stressors, that reduce the ability of trees to store carbon in woody tissues. A diversity of tree-ring-based chronologies can describe the sensitivity of carbon stores to these stressors, improving predictions of how forests respond to environmental changes.

Waste products from the forest industry are to be spread in forests in Sweden to counteract nutrient depletion due to whole tree harvesting. This may increase the bioavailability of calcium (Ca) and heavy metals, such as cadmium (Cd), copper (Cu) and zinc (Zn) in forest soils. Heavy metals, like Cd, have already been enriched in forest soils in Sweden, due to deposition of air pollutions, and acidification of forest soils has increased the bioavailability of toxic metals for plant uptake. Changes in the bioavailability of metals may be reflected in altered accumulation of Ca and heavy metals in forest trees, changes in tree growth, including wood formation, and altered tree species composition. This thesis aims at examining: A) if inter- or intra- specific differences in sensitivity to Cd occur in the most common tree species of Sweden, and if so, to study if these can be explained by the uptake and distribution of Cd within the plant: B) how elevated levels of Ca, Cd, Cu and Zn affect the accumulation and attachment of metals in bark and wood, and growth of young Norway spruce (Picea abies): C) how waste products from the forest industry, such as wood ash, influence the contents of Ca, Cd, Cu and Zn in wood and bark of young Norway spruce.

Sensitivity to Cd, and its uptake and distribution, in seedlings of Picea abies, Pinus sylvestris and Betula pendula from three regions (southern, central and northern parts) of Sweden, treated with varying concentrations of Cd, were compared. Differences in root sensitivity to Cd both among and within woody species were found and the differences could to some extent be explained by differences in uptake and translocation of Cd. The root sensitivity assays revealed that birch was the least, and spruce the most, sensitive species, both to the external and to tissue levels of Cd. The central ecotype of the species tested tended to be most Cd resistant.

The radial distribution, accumulation and attachment of, and interactions between Ca and heavy metals in stems of two-year-old Norway spruce trees treated with elevated levels of Cd, Cu, Zn and/or Ca, were investigated. Further, the influence of these metals on growth, and on root metal content, was examined. Accumulation of the metals was enhanced in wood, bark and/or roots at elevated levels of the metal in question. Even at low levels of the metals, similar to after application of wood ash, an enhanced accumulation was apparent in wood and/or bark, except for Cd. The increased accumulation of Zn and Cu in the stem did not affect the growth. However, Cu decreased the accumulation of Ca in wood. Higher levels of Cu and Cd reduced the stem diameter and the toxic effect was associated with a reduced Ca content in wood. Copper and Cd also decreased the accumulation of Zn in the stem. On the other hand, elevated levels of Ca increased the stem diameter and reduced the accumulation of Cd, Cu, Zn and Mn in wood and/or bark. When metals interacted with each other the firmly bound fraction of the metal reduced was in almost all cases not affected. As an exception, Cd decreased the firmly bound fraction of Zn in the stem.

The influence of pellets of wood ash (ash) or a mixture of wood ash and green liquor dregs (ash+GLD), in the amount of 3000 kg ha^-1, on the contents of Ca, Cd, Cu and Zn in wood and bark of young Norway spruce in the field was examined. The effect of the treatments on the metal content of bark and wood was larger after 3 years than after 6 years. Treatment with ash+GLD had less effect on the heavy metal content of bark and wood than treatment with ash alone. The ash treatment increased the Cu and Zn content in bark and wood, respectively, after 3 years, and decreased the Ca content of the wood after 6 years. The ash+GLD treatment increased the Ca content of the bark and decreased the Zn content of bark and wood after 3 years. Both treatments reduced, or tended to decrease, the Cd content in wood and bark at both times.

To conclude, small changes in the bioavailability of Ca, Cu, Cd and Zn in forest soils, such as after spreading pellets of wood ash or a mixture of wood ash and green liquor dregs from the forest industry, will be reflected in an altered accumulation of metals in wood and bark of Norway spruce. It will not only be reflected in changed accumulation of those metals in which bioavailability in the soil has been enhanced, but also of other metals, probably partly due to interactions between metals. When metals interact the exchangeable bound fraction of the metal reduced is suggested to be the main fraction affected. The small alterations in accumulation of metals should not affect the growth of Norway spruce, especially since the changes in accumulation of metals are low, and further since these decrease over time. However, as an exception, one positive and maybe persistent effect of the waste products is that these may decrease the accumulation of Cd in Norway spruce, which partly may be explained by competition with Ca for uptake, translocation and binding. A decreased accumulation of Cd in Norway spruce will probably affect the trees positively, since Norway spruce is one of the most sensitive species to Cd of the forest trees in Sweden. Thus, spreading of waste products from the forest industry may be a solution to decrease the accumulation of Cd in Norway spruce. In a longer perspective, this will decrease the risk of Cd altering the tree species composition of the forest ecosystem. An elevated bioavailability of Ca in forest soils will, in addition to Cd, probably also decrease the accumulation of other less competitive heavy metals, like Zn and Mn, in the stem.

Translocation of nitrogen (N) through mycelial cords of wood decay fungi is thought to be the mechanism responsible for the observed increase in absolute N content in woody debris over time. This research evaluates the ability of the mycelial cords of the wood ¹⁵decay fungus Hypholoma fasciculare to translocate and accumulate labeled organic (¹⁵N-glycine, N Douglas-fir litter) and inorganic N (¹⁵NH₄⁺, ¹⁵NO₃⁻) in its wood substrate. Each N form was supplied separately to the growing fronts of mycelial cords established over 67 days from wood blocks (Douglas-fir) in soil microcosms. Three sampling occasions (days 6, 18 and 30 after N addition) were used to identify trends in ¹⁵N transfer and total N accumulation. Wood blocks inoculated with Hypholoma fasciculare assimilated significantly more ¹⁵N than uninoculated blocks for all ¹⁵N treatments on at least one sampling occasion. After 73 days of incubation (day 6 sampling occasion), inoculated wood blocks increased in absolute N content by 211% relative to uninoculated control blocks, but 80% of this accumulated N was lost after 97 days of incubation (day 30 sampling occasion). The small amount of ¹⁵N that was transferred contrasted with the large increase in total N, suggesting that the site of N transfer was largely from the soil underneath wood blocks rather than at the site of ¹⁵N injection. The precipitous decline in absolute N content was attributed to visible indications of mycelial senescence. This research demonstrates that the mycelial cords of Hypoloma fasciculare are capable of translocating ¹⁵N into a wood substrate and can also greatly increase the absolute N content of wood blocks. The results are discussed in the context of fungal ecology as well as woody debris management.

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This study seeks to understand the relationship of the process of capital accumulation in the wood processing industry and its relationship with the production of geographical space. The analysis of such a process takes into account the contradictions inherent in their development process. We seek to understand these contradictions, by pointing the main factors that encouraged the development of modern forestry, based on scientific research, especially in relation to raw material, meeting the industrial needs. It was intended in this work demonstrate the relationship between the various geographical scales as the focal point of socio-spatial training for the consolidation of the timber industry in the state of Parana.
O presente trabalho busca compreender a relação do processo de acumulação de capital no setor de transformação de madeira e sua relação com a produção do espaço geográfico. A análise de tal processo leva em consideração as contradições inerentes ao seu prodesso de desenvolvimento. Buscamos compreender essas contradições apontando os principais fatores que propiciam o desenvolvimento de uma moderna silvicultura, baseada em pesquisas científicas, sobretudo em relação à matéria-prima, atendendo as necessidades industriais. Pretendeu-se no decorrer do trabalho demonstrar a relação entre as diversas escalas geográficas como ponto central da formação sócio-espacial para a consolidação da indústria madeireira no Estado do Paraná.

Biomes classified as Brazilian Atlantic Forest (BAF) and the Chilean Mediterranean forest (CMF) have been affected by anthropic pressure that has caused a considerable decrease of their forest surfasse. However, they are rich in biodiversity and they provide many ecosystem services and were, therefore, classified as \"hotspots\" (forests in risk). Therefore, is essential to study the natural dynamics and the climatic response of the trees of these forests to include conservation projects and strategic measures. To achieve these objectives, the scientific literature reports that tree growth rings are the only ecological indicators with annual resolution that can be efficient and highly accurate to obtain this information. In this context, the research project has as main objective the retrospective analysis of radial growth of forest species in different vegetation communities of BAF and CMF in response to climatic changes. To achieve this goal, four key questions were elaborated: 1) Which variable explains betterthe variability of radial growth at different spatial and temporal scales? 2) What is the growth resilience to recent climate changes? 3) Is there some more vulnerable population to expected climatic changes?. A total of five sites (seven populations) of Cedrela odorata and C. fissilis in BAF from the State of São Paulo in Brazil, and five sites (10 populations) of Nothofagus macrocarpa (FMC) from the central region of Chile were sampled, using a non-destructive method. Four chapters were developed to answer these questions. Chapter I seek to analyze the resilience in radial growth to changes in regional climate variability and droughts, in temporal and spatial scale, on Atlantic forest remnant forests of biogeographic region Serra do Mar. Results show that radial growth in wet sites (winter rains exceed 240 mm) depend on the moisture conditions in dry season, while the higher population is more sensitive to the favorable summer water condition, which would be explained because this population received a lower temperature than the other Cedrela spp. populations studied. Chapter II analyzed how recent climatic variability affected the radial growth in N. macrocarpa populations. It is observed that all the populations are closely linked to the precipitations of May-November (end of autumn/end of spring) and average temperature of October-December (mid-spring/early summer). In Chapter III, we continued exploring the growth responses to climate in the FMC populations in order to find biogeographic differences. In this sense, we evaluated if this significant decrease in tree growth is differentiated between populations and age classes, and determine if the positive effect of CO2 fertilization compensates the precipitation decrease and temperature increase in the last decades in the growth of older, maturer and younger trees . Results show a significant negative trend in all classes from the year 2000, which would be associated to a decrease in precipitation in all populations while temperature was more associated with the northern and southern populations (distribution limit). We did not find a positive effect of rising CO2. Finally, chapter IV integrated the results of the two biomes comparing the projections of aboveground trees biomass under two climatic scenarios of CMIP5 project (light and severe), in order to know which populations are more vulnerable to rising temperature forecasted by year 2100, using ring width data, wood density and allometric equations. This study will provide an overview of adaptation to recent and projected climatic changes of two hotspot neotropical biomes. Although they are different in structure-biodiversity-climate are in risk. Thus, we can understand the vulnerability of threatened forests in South America to global warming that, although they are in protected areas, does not guarantee their persistence.
Os biomas classificados como Mata Atlancia Brasileira (MAB) e da Floresta Mediterrânea Chilena (FMC) têm sido afetados pela pressão antrópica que tem causado uma diminuição considerável de sua superfície florestal. No entanto são ricas em biodiversidade e providenciam muitos serviços ecossistêmicos, pelo que foram classificadas como hotspot (florestas em risco). Portanto, é fundamental estudar a dinâmica natural e a resposta climática das árvores dessas florestas para incluir em projetos de conservação. Para atingir esses objetivos, a literatura científica reporta que os anéis de crescimento das árvores são os únicos indicadores ecológicos com resolução anual que podem ser eficientes e de elevada precisão para obter essas informações. Neste contexto, o projeto de pesquisa tem como objetivo geral a analise retrospectivo de crescimento radial de espécies florestais em diferentes comunidades vegetacionais da MAB e FMC em resposta às mudanças climaticas. Para atingir esse objetivo foram elaboradas quatro perguntas-chave: 1) Que variable explica melhor a variabilidade do crescimento radial a diferentes escalas espaciais e temporais? 2) Qual é a resiliência em crescimento das árvores às mudanças climáticas recentes? 3) Há alguma população mais vulnerável respeito às mudanças climaticas esperadas?. Foram coletadas amostras de lenho, através de método não destrutivo, de cinco sitios (sete populações) de Cedrela odorata e C. fissilis na MAB no estado de São Paulo em Brasil, e cinco sitios (10 populações) de Nothofagus macrocarpa na FMC na região central do Chile, para aplicação de tecnicas dendrocronologicas. Para responder essas questões foram desenvolvidos quatro capitulos. O capitulo I busca analisar a resiliência em crescimento radial às mudanças na variabilidade climática regional e secas, em escala temporal e espacial, em florestas remanentes da região biogeográfica Serra do Mar da Mata Atlântica, usando as especies bioindicadoras Cedrela fissilis and C. odorata. Os resultados mostram que o crescimento radial dos sítios mais úmidos (chuvas no inverno superam os 240 mm) dependem das condições hidricas da estação seca, enquanto que a população mais alta é mais sensível à condição hídrica favorável do verão, qual seria explicado porque essa população recebi uma menor temperatura respeito às outras populações de cedrela estudadas. No capitulo II analisou-se como a variabilidade climática recente estaria afeitando o crescimento radial in N. macrocarpa populations. Observa-se que todas as populações estão estreitamente ligadas às precipitações de Maio-Novembro (fim de outono/fim de primaveira) e temperatura média de Outubro-Dezembro (mediados de primaveira/inicios do verão). Especificamente, há uma tendencia negativa significativa no crescimento radial apartir de 1980 que esta associada a uma variação do clima regional. No capitulo III, continuo-se explorando as respostas do crescimento radial ao clima nas populações da FMC com objetivo de encontrar diferencias biogeográficas. Neste sentido, foi avaliado se essa diminuição significativa de crescimento é diferenciada entre populações e classes de idade, e analisar se o efeito positivo da fertilização de CO2 compensa a diminuição da precipitação e aumento da temperatura nas ultimas decadas no crescimento de árvores velhos, maduros e jovens. Os resultados mostram uma tendencia negativa significativa em todas as clases apartir do ano 2000, qual estaria associada a diminuição da precipitação em todas as populações enquanto a temperatura teve mais associada às populações do sul. Não foi encontrado um efeito positivo do aumento de CO2. Finalmente, o capitulo IV integrou os resultados dos dois biomas comparando as proyeções de biomasa arborea sob dois escenarios climáticos do projeto CMIP5 (leve e severo), com objetivo de conocer quais populações são mais vulneraveis ao aumento da temperature previsto para o ano 2100, usando crescimento radial, densidade de madeira e ecuações alométricas. Os resultados mostram que a população com maior influencia urbana e a mais seca são as mais vulneráveis ao aumento exarcerbado de temperatura nas regiões de MAB and FMC, respectivamente. O presente estudo permitiu-nos apresentar uma visão da adaptação às mudanças climáticas recentes e projetadas de dois biomas hotspot. Embora sejam diferentes em estrutura-biodiversidade-clima estão em risco. Assim, podemos entender a vulnerabilidade de florestas neotropicais ao aquecimento global, embora estejam em áreas protegidas, não garante sua persistência.

This thesis investigates the characteristics and impacts of large wood accumulations within river reaches of different size and style. Four reaches were studied: (i) a wide, braided, headwater reach, characterised by dead wood (Tagliamento River, Italy); (ii) a lower gradient, wide, braided reach, characterised by resprouting wood (Tagliamento River, Italy); (iii) a low gradient, single thread reach with a natural supply of dead wood (Highland Water, UK), and (iv) a low gradient, single thread reach that has been restored by felling trees into the river (River Bure, UK). In each reach, quantities of wood, types of accumulation and their association with sediment retention, landform and propagule bank development were investigated, generating four main findings: 1. There were marked differences in the size and character of large wood accumulations among the four reaches. 2. Retention of fine sediment and organic matter by wood was observed on all four reaches, giving rise to notable spatial heterogeneity in surface sediments. 3. Sediment retention resulted in the development of different landforms among the four reaches. In the two multi-thread reaches, accretion of finer sediment around large wood led to island development. In the naturally-functioning single-thread reach, wood jams spanned the river channel, accumulating sediment and organic matter to produce unvegetated wood jams, and inducing other landforms, notably pools and bars. Such geomorphic heterogeneity was anticipated in the restored reach, but to date this has not significantly occurred. 4. Spatio-temporal variations were observed in propagule abundance and species richness within different wood-related mesohabitats. Higher abundance and species richness were associated with finer, more organic sediments retained within wood accumulations and related mesohabitats. In the restored reach such associations were not statistically significant, further indicating that responses to wood emplacement take longer than the 4 years since restoration. iv Overall, this research has strengthened the evidence concerning the differing nature of wood accumulations in rivers of different size and style, and it has demonstrated the importance of large wood for retaining organic matter and plant propagules, resources essential for riparian vegetation succession and for the success of river restoration efforts.

Accounting for in-woods carbon storage in carbon accounting systems may be insufficient when substantial amounts of sequestered carbon are harvested and converted to long-lived wood products and landfills. The potential for offsetting greenhouse gas (GHG) emissions by storing carbon in managed loblolly pine forests in the southern United States was projected over the next half-century, both in terms of in-woods aboveground carbon pools and harvested products, including wood used for energy production. A region-wide data set from the Forest Inventory Analysis (FIA) program of USDA Forest Service was used to set initial conditions and estimate model parameters for projecting management activities including plantation area, age distributions of thinning, and clearcut harvest on an annual timestep. The stand-level growth and yield model FASTLOB was linked to the FIA data to project growth rates and annual harvest volumes of sawtimber and pulpwood for the projection period, accounting for annual timber harvests and the life cycles of wood products. In addition to baseline management practices, projections were made for scenarios that assumed increasing management intensities including the use of chemical fertilizers and herbicides and genetically-improved growing stock. Present-day carbon storage in well-managed southern pine plantations averaged 30.54 Mgâ ha-1 (± 2.54%) for aboveground carbon. Over a 50-year projection, annual wood production was 62.1 and 45.9 million green metric tons from pulpwood and sawtimber yield, with roughly one-fourth of the green weight being carbon. Baseline projections showed aboveground carbon pools of up to 341 million metric tons being maintained over the next 50 years, with 93% in aboveground live trees and 7% in coarse woody debris (CWD). The carbon storage in wood products increased steadily over the half-century projection and showed no sign of leveling off, while the storage in plantations was found to remain constant or increase slightly over time. An additional 11 million metric tons of harvested carbon was used for energy per year on average, equivalent to 25% of annual forest-products-industry renewable energy use in U.S.A. Intensified forest management practices showed the potential to increase as much as 30% total carbon stored in in-woods and harvested-wood-products pools, with potential increases up to 40% in energy offsets above the baseline scenario. Reducing management intensity greatly increased in-woods carbon storage potential, but eliminated the wood-products carbon sink.
Ph. D.

One of the main routes through which pharmaceuticals may enter the environment consists in the medication of livestock. In fact, in Europe the annual national sales of active substance for veterinary consumption reach hundreds of tons. After medication, up to 90% of the administered medicine dose may be excreted unaltered and, following the use of manure as fertilizer, soils and waters are contaminated. The present work focuses on the effects and eventual accumulation on woody and herbaceous plants of sulfonamides, a group of antimicrobial agents (from now on called antibiotics) frequently detected in agricultural ecosystems, whose persistence poses a serious risk to soil and water living organisms. The thesis consists of 7 chapters, presenting, in the first one, a general introduction on the antibiotic presence in the environment and its consequences on the growth and development of exposed living organisms. Subsequently, from chapter 2 to chapter 6, various experimental trials are presented, some of them carried out under laboratory conditions and others in greenhouse. More specifically, chapter 2 reports the first study performed, which deals with Salix fragilis L. plant response and the accumulation of sulfadimethoxine antibiotic, added in the nutrient solution at doses ranging from 155 to 620 mg l-1. Such a study highlights the potential of this woody species to absorb and accumulate the active molecule at the level of root apparatus. Chapter 3 retraces the experimental design of chapter 2, with the difference that Salix fragilis L. plants were exposed to environmental relevant sulfadimethoxine doses, from 0.01 up 10 mg l-1. The trial had demonstrated that no adverse effects on the growth of willow plants appeared up to 1 mg l-1 of antibiotic. Conversely, increasing levels of the antibiotic caused important alterations of the willow root architecture. Chapters 4 and 5 consider, respectively, the effects and accumulation of a different sulfonamide on Salix fragilis L. and Zea mays L. plants, grown in a soil spiked with 10 and 200 mg kg-1 of sulfadiazine. Moreover, its impact on the composition of root associated soil microbial community and on the activities of selected enzymes was analyzed. The last study, presented in chapter 6, focuses on alterations induced by about 10 mg l-1 of sulfadimethoxine and sulfamethazine on Hordeum vulgare L. root structure and function. This chapter highlights the strong effects of the antibiotics, not only on the root apparatus morphology, but also on the membrane integrity of root cells. To conclude (chapter 7), it is highlighted that Salix fragilis L. seems to better accumulate and withstand the active molecules tested than Zea mays L. and Hordeum vulgare L., while the herbaceous species are more vulnerable to this kind of pollutant exposure and, therefore, not recommended for eventual remediation purposes. Furthermore, chapter 7 notes the adverse consequences on the functional and structural diversity of the soil microbial community.
Una delle vie principali attraverso cui i farmaci possono entrare nell'ambiente consiste nell’ampio uso che se ne fa in zootecnia. Infatti, in Europa questi principi attivi sono venduti nell’ordine di centinaia di tonnellate annue per singola nazione, per il solo utilizzo in ambito veterinario. In seguito alla somministrazione, fino al 90% della dose utilizzata di farmaco può essere escreta inalterata e, in seguito all'utilizzo del letame come ammendante organico, suolo e acque possono risultare contaminate. Il presente studio si concentra sugli effetti e sull’accumulo in piante legnose ed erbacee di sulfamidici, un gruppo di agenti antimicrobici (d'ora in poi chiamati antibiotici) frequentemente rilevati negli ecosistemi agrari, la cui persistenza rappresenta un serio rischio per gli organismi viventi ad essi connessi. La tesi è articolata in 7 capitoli. Nella prima parte (capitolo 1) è descritta la situazione generale relativa alla presenza di antibiotici negli ambienti agrari e al loro impatto sulla crescita e lo sviluppo di organismi viventi ad essi esposti. Successivamente, dal capitolo 2 al capitolo 6, sono presentate varie prove sperimentali, alcune effettuate in laboratorio ed altre in serra. In particolare, il capitolo 2 si occupa della risposta di piante di Salix fragilis L. all’antibiotico sulfadimetossina, aggiunto alla soluzione nutritiva in concentrazioni da 155 a 620 mg l-1, nonché del potenziale accumulo nei tessuti vegetali. Lo studio mostra la tendenza di questa specie legnosa di assorbire e accumulare la molecola attiva a livello di apparato radicale. Il capitolo 3 ripercorre il disegno sperimentale adottato nella prova descritta nel capitolo 2, con la differenza che, in questo caso, le piante di Salix fragilis L. sono state esposte a dosi di sulfadimetossina che approssimano quelle registrate in alcuni ambientali agrari, ovvero da 0.01 a 10 mg l-1. Lo studio ha mostrato che non appaiono effetti negativi sulla crescita delle piante di salice fino alla dose di 1 mg l-1. Tuttavia, aumentando il livello del principio attivo sono state evidenziate delle importanti alterazioni sull’architettura radicale. I capitoli 4 e 5 considerano, rispettivamente, gli effetti e l'accumulo di un altro sulfamidico in piante di Salix fragilis L. e Zea mays L., coltivate in un terreno arricchito con 10 mg e 200 kg-1 di sulfadiazina e il suo impatto sulle comunità microbiche e sulle attività enzimatiche associate al suolo e alla radice delle due specie vegetali. L'ultimo studio, presentato nel capitolo 6, si concentra sugli effetti indotti da circa 10 mg l-1 di sulfadimetossina e sulfametazina sulla struttura e sulla funzionalità di radici di Hordeum vulgare L. I risultati provano che i sulfamidici causano importanti effetti sulla morfologia dell'apparato radicale e sull’integrità delle membrane delle cellule radicali. Concludendo, si è evidenziato (capitolo 7) che il Salix fragilis L. accumula e tollera meglio di Zea mays L. e Hordeum vulgare L. le molecole attive testate, mentre le specie erbacee sembrano essere più vulnerabili a questi inquinanti, di cui ne viene sconsigliato l’eventuale utilizzo nel campo del fitorimedio. Inoltre, in capitolo 7 rimarca le conseguenze negative sulla diversità funzionale e strutturale delle comunità microbiche del suolo.

Soil that is heavily contaminated with polycyclic aromatic hydrocarbons (PAHs) is often found at the sites of former gasworks and wood-impregnation plants. Since PAHs are toxic these sites represent a hazard to human health and the environment, and therefore they need to be treated, preferably by a method that destroys the contaminants, and thus eliminates the problem permanently. However, during biological and chemical degradation of PAHs other toxic compounds may be formed. If these transformation products are sufficiently persistent they could potentially accumulate during remedial processes. In the work underlying this thesis the degradation and transformation of PAHs were studied in three remedial processes: viz. a pilot-scale bioslurry reactor, microcosms with wood-rotting fungi and lab-scale treatments with Fenton's reagent. A group of transformation products referred to as oxygenated-PAHs (oxy-PAHs) was found to be particularly important, as these compounds are toxic and were shown to be relatively persistent in the environment. The oxy- PAHs were, for instance, found at significant concentrations in the gasworks soil used in most of the studies. This soil was highly weathered and had therefore been depleted of the more readily degradable compounds. In addition, experiments in which earthworms were exposed to the gasworks soil showed that the oxy-PAHs were more easily taken up in living organisms than PAHs. To facilitate the studies, new extraction and fractionation methods were developed. For instance, pressurized liquid extraction (PLE) was investigated for its reliability and efficiency to extract PAHs and oxy-PAHs from soil. Furthermore, a selective PLE-method was developed that can simultaneously extract and separate the PAHs and oxy-PAHs into two different fractions. This was accomplished by adding a chromatographic material (silica or Florisil) to the extraction cell. Under certain conditions all three remedial processes resulted in increasing amounts of oxy- PAHs in the soil. For example, 1-acenaphthenone and 4-oxapyrene-5-one accumulated in the bioslurry reactor. Similarly, in the soil inoculated with a white-rot fungus 9-fluorenone, benzo[a]anthracene-7,12-dione, 4-hydroxy-9-fluorenone and 4-oxapyrene-5-one accumulated. Finally, in an ethanol-Fenton treatment the concentration of some PAH-quinones increased in the soil. The results show that it might be necessary to monitor oxy-PAHs as well as PAHs during the remediation of PAH-contaminated sites. Otherwise, the soil may be considered detoxified too early in the process. In the long term it would be desirable to include analyses with sufficient marker compounds to follow the possible production and elimination of the oxy-PAHs. However, until such compounds can be identified it is suggested that contaminated soil should be screened for oxy-PAHs in general. The selective PLE-method presented in this thesis could be a useful tool for this.

This thesis is about the organisation, character and change of labour relations in expanding capitalist wool farming in the Cape between 1860 and 1950. It is an attempt to analyse labour in wool farming within a transnational framework, based on an expansion of capital from core to periphery of the capitalist world-economy. Wool farming in peripheries like the Cape was part of capitalist production through the link to primarily the British textile industry. This relationship enabled wool farmers to invest in their farms in sheep, fences and windmills. They thereby became agents of capital expansion in the world-economy, which was a prerequisite for a capitalist expansion. Although wool production in the Cape was initially an imperial division of labour, that relation changed during the twentieth century as Britain’s leading role as textile producer was challenged by other capitalist core countries. Capitalism as a transnational production system, based on commodity chains from periphery to core, became the most crucial structure for wool farmers in the Cape, who could increase their exports. The thesis also shows that the pre-capitalist generational division of labour among black peasants, through which farmers acquired labour, especially shepherds, was both discarded and intensified. Shepherding was intensified along with fencing during the late nineteenth and early twentieth century due to threat from jackals and lack of sufficient water supplies. Those farmers who invested in technology in the form of jackal-proof fences and windmills managed to change production from herding to rotational grazing in camps, which meant that shepherds were replaced by camp walkers, who controlled fences instead of sheep. Those farmers who did not invest were forced to exploit the pre-capitalist relations more intensively and hire shepherds in order to be able to produce and sell wool to textile manufacturers in capitalist core areas. As the young adult males disappeared from farms to the mines, the role of children and youths as shepherds became increasingly important. By the 1940s almost all the shepherds were children or youths, but they were about to be made redundant, as the number of shepherds decreased during the 1930s and 1940s.

Studies of mating systems and social organisation have been central to understanding of the evolution of social behaviour. The European badger Meles meles is a good species in which to study these processes, as its complex social system provides an opportunity to investigate how both natural and kin selection shape the evolution of mating systems and social structure. In this thesis, I use behavioural and genetic data to describe the mating system and social organisation of a high-density badger population and examine the occurrence of cooperative breeding. I genotyped 915 (85%) badgers trapped in Wytham Woods (1987–2005), 630 of which were cubs, and assigned both parents to 331 cubs with 95% confidence. This revealed a polygynandrous mating system, with up to five mothers and five fathers per social group. Mounting behaviour was also polygynandrous and I show the strongest evidence to date for multiple-paternity litters. I demonstrate, for the first time, that groups consisted of close and distant kin: approximately one third of group members were first-order kin, and overall group members had slightly lower relatedness levels than half-siblings. Within groups, adult and yearling females had higher pairwise relatedness than males, and neighbouring groups contained relatives. These findings result from the high level (42%) of extra-group paternities, 86% of which were assigned to neighbouring males. For the first time I show that females avoided inbreeding by mating with extra-group males; however, incestuous matings did occur. Promiscuous and repeated mountings were observed, which may reduce male–male aggression and infanticide, but may also promote sperm competition, genetic diversity, and / or genetic compatibility. Just under a third of adult males and females were assigned parentage each year and I quantify, for the first time, reproductive skew within badger groups. Correlations between relatedness, group productivity, and reproductive skew were not consistent with the predictions of incomplete-control models; rather, resource availability may play a role. Older and younger badgers displayed reduced annual breeding success, with male success increasing initially with experience. The Restraint, Constraint, and Selection Hypotheses did not explain the age-related breeding pattern in females. Variance in lifetime breeding success (LBS) was greater for males. Males that only bred within or only outside of their groups had half the LBS of males that did both. Females that were assigned maternity probably bred cooperatively and allonursed non-offspring, which has not been demonstrated previously. No benefit was established, however, in terms of litter size, probability of offspring breeding, or offspring lifetime breeding success, with more mothers in a group. In conclusion, badger social groups are fostered through kinship ties. Polygynandry and repeated mounting may have evolved originally to reduce male–male aggression and infanticide by males, through paternity masking. Although plural breeding occurs, group living appears to be costly. Motivation to disperse may be reduced through high-levels of extra-group paternities, which may also reduce inbreeding. Cooperative breeding among mothers may represent a low-cost behaviour with indirect benefits due to high levels of relatedness between female group-members. Badger sociality therefore represents an early stage in the evolution of social behaviour.

Wood accumulation at bridges exerts additional forces to the structures and aggravates local scouring around piers, which may result to bridge failure. Moreover, it may considerably reduce the flow opening causing higher flow levels and inundation of nearby areas. On the other hand, the important ecological role of instream wood in fluvial systems calls for a compromise between preservation of river ecosystems and prevention of instream wood-related hazards. The present PhD research aims to enhance the knowledge on the process of interaction between wood and bridge piers. The two main objectives were first to find the wood accumulation probability (here called “blockage probability”) as a function of the bridge pier geometry (with a focus on non-standard pier shapes typical of historical cities), hydraulic conditions of the approaching flow, and wood transport regime, second to assess the capability of 2D and 3D numerical models in reproducing the interaction between wood and structures (i.e. the bridge pier). The combined experimental and numerical research approach is used. The results showed that blockage probability at the flatter pier shape is three times greater than the triangular shaped piers, in congested wood transport regime and at high Froude number (in this case Fr=0.5). In case of Ogival pier, zero blockage probability was found for both cases of Froude numbers. Potential flow analysis indicated that the lower curvature of the streamlines at the rounded pier favours the log sliding the pier. Despite the capability of the 2D model in reproducing the log transport, the discrepancy between experimental and the 2D numerical results showed the inability of modelling the important secondary flows and the log-pier interactions. Furthermore, the 3D modelling allowed to reproduce the 3D character of the wood-pier interaction process as the logs that move along the vertical upstream face of the pier, the non-elastic collision between logs and between logs and the pier, and the skin friction of logs. Finally, one of the main novelties of the current research is represented by the definition of a new pier hydraulic-shape coefficient () that takes into account the shape of the pier and the 2D velocity flow field upstream of the pier. The thesis was also successful in defining the joint blockage probability at a bridge pier for the prevailing variables used in the study. The concept should find applications both in research and practical situation.

碩士
國立交通大學
電子工程系所
94
This thesis presents the design methodology of a high-performance reconfigurable multiplier-accumulator (MAC) capable of supporting sub-word parallelism (SWP) and additional features such as mixed-mode operation and flexible sub-word combination and mode assignment scheme. In order to perform SWP on the proposed scalar MAC, a new SWP partial product array and a novel speed-optimized SWP partial product reduction tree are proposed. With slight delay and some area overhead, the SWP MAC utilizes essentially the same hardware as the proposed scalar MAC. The whole design is dynamically reconfigurable, fully-synthesizable, reusable, and verifiable. The proposed designs and previous relevant works are implemented and compared. Experimental results demonstrate that the proposed SWP MAC design theoretically and practically improves and outperforms previous works in terms of critical path delay, area cost, and power consumption.

Dissertação de mestrado em Biologia Molecular, Biotecnologia e Bioempreendedorismo em Plantas
Grapevine (Vitis vinifera L.) is one of the world's most widely cultivated fruit species. The source/sink ratio is an important agronomical parameter that influences the sensory properties of the berries and plant productivity. Also, it may alter starch reserves accumulated in the amyloplast of sink tissues, like the woody canes, trunk, and roots, that are necessary to sustain rapid seasonal growth phases typical of the grapevine. Thus, in this study, we took advantage of the ability to precisely control the number of leaves to fruits in grapevine fruiting-cuttings to study the effect of source/sink ratio (2L, two leaves per cluster; 6L, six leaves per cluster, and 12L, twelve leaves per cluster) on the metabolism and accumulation of starch in canes. Cabernet Sauvignon fruiting-cuttings were selected and the work was carried out in collaboration with the Institut des Sciences de la Vigne et du Vin (ISVV) from Bordeaux - France. The total amount of starch was significantly higher in canes from 6L (42.13 ± 1.44 mg g DW-1) and 12L (43.50 ± 2.85 mg g DW-1) than in 2L (22.72 ± 3.10 mg g DW-1) fruiting-cuttings. Moreover, carbon limitation promoted a transcriptional adjustment of genes involved in starch metabolism in grapevine woody tissues. For instance, the expression of VvGPT1 and VvNTT, that code for plastidic glucose-6-phosphate/phosphate and ATP/ADP translocators, respectively, were upregulated in one-year canes from 12L plants. Contrarily, the transcript levels of the gene coding the catalytic subunit VvAGPB1 of the VvAGPase complex were higher in canes from 2L plants than in 6L and 12L, which positively correlated with the biochemical activity of this enzyme measured in tissue protein extracts. Soluble sugars were analyzed in one-year canes, and it was found that sucrose concentration increased significantly from 2L to 6L and 12L plants, and the amount of total phenolics followed the same trend. In agreement, qRT-PCR showed that the expression of VvSusy (Vitis vinifera Sucrose synthase) decreased from 2L plants to 6L and 12L, which correlated with the biochemical activity of insoluble invertase measured in tissue protein extracts. Contrarily, the expression of the sugar transporters VvSUC11 and VvSUC12, together with VvSPS1, which codes an enzyme involved in sucrose synthesis, increased from 2L plants to 6L and 12L. Overall, the results obtained in this work suggested that a mechanism regulating starch accumulation involving sucrose as a signal molecule is occurring in grapevine woody tissues in response to source/sink modulation, and that severe leaf removal may have short- and medium-term negative effects in plant productivity.
A videira (Vitis vinifera L.) é uma das espécies frutícolas mais cultivada a nível mundial. O rácio entre os tecidos produtores e de armazenamento (“source/sink”) é um parâmetro agronómico importante que influencia as características sensoriais do bago, bem como a produtividade da planta. Além disso, o rácio “source/sink” pode alterar a acumulação de amido nos amiloplastos de tecidos de armazenamento, como as varas lenhosas, troncos e raízes, que são necessários para o crescimento sazonal rápido típico da videira. Assim, no presente estudo, utilizámos o modelo de estacas enraizadas de videira que permite controlar com precisão o rácio “source/sink” (2L, duas folhas por cacho; 6L, seis folhas por cacho e 12L, doze folhas por cacho) e estudar o seu efeito no metabolismo e acumulação de amido nas varas. Foram utilizadas videiras da variedade Cabernet Sauvignon e o trabalho decorreu em colaboração como o Institut des Sciences de la Vigne et du Vin (ISVV) de Bordéus – França. Os níveis de amido medidos foram significativamente superiores em varas de plantas 6L (42,13 ± 1,44 mg/g peso seco) e 12L (43,50 ± 2,85 mg/g peso seco) do que de plantas 2L (22,72 ± 3,10 mg/g peso seco). Em paralelo, observou-se que a remoção das folhas promoveu uma reprogramação ao nível transcricional de genes envolvidos no metabolismo do amido nos tecidos lenhosos. Por exemplo, a expressão dos genes VvGPT1 e VvNTT, que codificam os trocadores plastidiais glucose-6-fosfato/fosfato e ATP/ADP, respetivamente, foi estimulada em varas de um ano de plantas 12L. Contrariamente, os níveis de transcrição do gene que codifica a subunidade catalítica VvAGPB1 do complexo VvAGPase foram mais elevados em varas de plantas 2L do que em varas de plantas 6L e 12L, tendo-se verificado uma correlação com a atividade bioquímica da enzima medida em extratos proteicos dos tecidos. Os açúcares solúveis nas varas de um ano foram analisados e os resultados demostraram que a concentração de sacarose aumentou significativamente em varas de plantas 2L para 6L e 12L, e que a quantidade de compostos fenólicos totais seguiu a mesma tendência. Em paralelo, estudos de expressão por qRT-PCR revelaram que os níveis de transcritos do gene VvSusy (Vitis vinifera Sucrose synthase) diminuíram em varas de plantas 2L para 6L e 12L, tendo-se identificado uma correlação com a atividade bioquímica da invertase insolúvel medida em extratos proteicos. Contrariamente, a expressão dos transportadores de açúcar VvSUC11 e VvSUC12, bem como a expressão do gene VvSPS1, que codifica uma enzima envolvida na síntese de sacarose, aumentou em varas de plantas 2L para 6L e 12L. No seu conjunto, os resultados sugeriram que a sinalização pelos níveis de sacarose está envolvida na regulação da acumulação do amido nos tecidos lenhosos da videira em resposta a modificações nas relações “source/sink” e que a desfolha severa pode ter efeitos negativos a curto e a médio prazo na produtividade da planta e na qualidade do fruto.