Soils contain a large amount of carbon (C) that is a critical regulator of the global C budget. Already small changes in the processes governing soil C cycling have the potential to release considerable amounts of CO2, a greenhouse gas (GHG), adding additional radiative forcing to the atmosphere and hence to changing climate. Increased temperatures will probably create a feedback, causing soils to release more GHGs. Furthermore changes in soil C balance impact soil fertility and soil quality, potentially degrading soils and reducing soils function as important resource. Consequently the assessment of soil C dynamics under present, recent past and future environmental conditions is not only of scientific interest and requires an integrated consideration of main factors and processes governing soil C dynamics. To perform this assessment an eco-hydrological modelling tool was used and extended by a process-based description of coupled soil carbon and nitrogen turnover. The extended model aims at delivering sound information on soil C storage changes beside changes in water quality, quantity and vegetation growth under global change impacts in meso- to macro-scale river basins, exemplary demonstrated for a Central European river basin (the Elbe). As a result this study: ▪ Provides information on joint effects of land-use (land cover and land management) and climate changes on croplands soil C balance in the Elbe river basin (Central Europe) presently and in the future. ▪ Evaluates which processes, and at what level of process detail, have to be considered to perform an integrated simulation of soil C dynamics at the meso- to macro-scale and demonstrates the model’s capability to simulate these processes compared to observations. ▪ Proposes a process description relating soil C pools and turnover properties to readily measurable quantities. This reduces the number of model parameters, enhances the comparability of model results to observations, and delivers same performance simulating long-term soil C dynamics as other models. ▪ Presents an extensive assessment of the parameter and input data uncertainty and their importance both temporally and spatially on modelling soil C dynamics. For the basin scale assessments it is estimated that croplands in the Elbe basin currently act as a net source of carbon (net annual C flux of 11 g C m-2 yr-1, 1.57 106 tons CO2 yr-1 entire croplands on average). Although this highly depends on the amount of harvest by-products remaining on the field. Future anticipated climate change and observed climate change in the basin already accelerates soil C loss and increases source strengths (additional 3.2 g C m-2 yr-1, 0.48 106 tons CO2 yr-1 entire croplands). But anticipated changes of agro-economic conditions, translating to altered crop share distributions, display stronger effects on soil C storage than climate change. Depending on future use of land expected to fall out of agricultural use in the future (~ 30 % of croplands area as “surplus” land), the basin either considerably looses soil C and the net annual C flux to the atmosphere increases (surplus used as black fallow) or the basin converts to a net sink of C (sequestering 0.44 106 tons CO2 yr-1 under extensified use as ley-arable) or reacts with decrease in source strength when using bioenergy crops. Bioenergy crops additionally offer a considerable potential for fossil fuel substitution (~37 PJ, 1015 J per year), whereas the basin wide use of harvest by-products for energy generation has to be seen critically although offering an annual energy potential of approximately 125 PJ. Harvest by-products play a central role in soil C reproduction and a percentage between 50 and 80 % should remain on the fields in order to maintain soil quality and fertility. The established modelling tool allows quantifying climate, land use and major land management impacts on soil C balance. New is that the SOM turnover description is embedded in an eco-hydrological river basin model, allowing an integrated consideration of water quantity, water quality, vegetation growth, agricultural productivity and soil carbon changes under different environmental conditions. The methodology and assessment presented here demonstrates the potential for integrated assessment of soil C dynamics alongside with other ecosystem services under global change impacts and provides information on the potentials of soils for climate change mitigation (soil C sequestration) and on their soil fertility status. / Böden speichern große Mengen Kohlenstoff (C) und beeinflussen wesentlich den globalen C Haushalt. Schon geringe Änderungen der Steuergrößen des Bodenkohlenstoffs können dazu führen, dass beträchtliche Mengen CO2, ein Treibhausgas, in die Atmosphäre gelangen und zur globalen Erwärmung und dem Klimawandel beitragen. Der globale Temperaturanstieg verursacht dabei höchstwahrscheinlich eine Rückwirkung auf den Bodenkohlenstoffhaushalt mit einem einhergehenden erhöhten CO2 Fluss der Böden in die Atmosphäre. Weiterhin wirken sich Änderungen im Bodenkohlenstoffhaushalt auf die Bodenfruchtbarkeit und Bodenqualität aus, wobei eine Minderung der Bodenkohlenstoffvorräte wichtige Funtionen des Bodens beeinträchtigt und folglich den Boden als wichtige Ressource nachhaltig beinflusst. Demzufolge ist die Quantifizierung der Bodenkohlenstoffdynamik unter heutigen und zukünftigen Bedingungen von hohem Interesse und erfordert eine integrierte Betrachtung der wesentlichen Faktoren und Prozesse. Zur Quantifizierung wurde ein ökohydrologisches Flusseinzugsgebietsmodell erweitert. Ziel des erweiterten Modells ist es fundierte Informationen zu Veränderungen des Bodenkohlenstoffhaushaltes, neben Veränderungen der Wasserqualität, der Wasserverfügbarkeit und des Vegetationswachstums unter Globalem Wandel in meso- bis makroskaligen Flusseinzugsgebieten bereitzustellen. Dies wird am Beispiel eines zentraleuropäischen Flusseinzugsgebietes (der Elbe) demonstriert. Zusammenfassend ergibt diese Arbeit: ▪ eine Quantifizierung der heutigen und zukünftigen Auswirkungen des Klimawandels sowie von Änderungen der Landnutzung (Bodenbedeckung und Bodenbearbeitung) auf den Bodenkohlenstoffhaushalt agrarisch genutzter Räume im Einzugsgebiet der Elbe. ▪ eine Beurteilung welche Prozesse, und zu welchem Prozessdetail, zur integrierten Simulation der Bodenkohlenstoffdynamik in der meso- bis makroskala zu berücksichtigen sind. Weiterhin wird die Eignung der Modellerweiterung zur Simulation dieser Prozesse unter der Zuhilfenahme von Messwerten dargelegt. ▪ darauf begründet wird eine Prozessbeschreibung vorgeschlagen die die Eigenschaften der Bodenkohlenstoffspeicher und deren Umsetzungsrate mit in der betrachteten Skala zur Verfügung stehenden Messdaten und Geoinformationen verbindet. Die vorgeschlagene Prozessbeschreibung kann als robust hinsichtlich der Parametrisierung angesehen werden, da sie mit vergleichsweise wenigen Modelparametern eine ähnliche Güte wie andere Bodenkohlenstoffmodelle ergibt. ▪ eine umfassende Betrachtung der Modell- und Eingangsdatenunsicherheiten von Modellergebnissen in ihrer räumlichen und zeitlichen Ausprägung. Das in dieser Arbeit vorgestellte Modellsystem erlaubt eine Quantifizierung der Auswirkungen des Klima- und Landnutzungswandels auf den Bodenkohlenstoffhaushalt. Neu dabei ist, dass neben Auswirkungen auf den Bodenkohlenstoffhaushalt auch Auswirkungen auf Wasserverfügbarkeit, Wasserqualität, Vegetationswachstum und landwirtschaftlicher Produktivität erfasst werden können. Die im Rahmen dieser Arbeit dargelegten Ergebnisse erlauben eine integrierte Betrachtung der Auswirkungen des Globalen Wandels auf wichtige Ökosystemfunktionen in meso- bis makro-skaligen Flusseinzugsgebieten. Weiterhin können hier gewonnene Informationen zur Potentialabschätzung der Böden zur Linderung des Klimawandels (durch C Festlegung) und zum Erhalt ihrer Fruchtbarkeit genutzt werden.

<p>At present, carbon sequestration in terrestrial ecosystems slows the growth rate of atmospheric CO₂ concentrations, and thereby reduces the impact of anthropogenic fossil fuel emissions on the climate system. Changes in climate and land use affect terrestrial biosphere structure and functioning at present, and will likely impact on the terrestrial carbon balance during the coming decades - potentially providing a positive feedback to the climate system due to soil carbon releases under a warmer climate. Quantifying changes, and the associated uncertainties, in regional terrestrial carbon budgets resulting from these effects is relevant for the scientific understanding of the Earth system and for long-term climate mitigation strategies.</p> <p>A model describing the relevant processes that govern the terrestrial carbon cycle is a necessary tool to project regional carbon budgets into the future. This study (1) provides an extensive evaluation of the parameter-based uncertainty in model results of a leading terrestrial biosphere model, the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM), against a range of observations and under climate change, thereby complementing existing studies on other aspects of model uncertainty; (2) evaluates different hypotheses to explain the age-related decline in forest growth, both from theoretical and experimental evidence, and introduces the most promising hypothesis into the model; (3) demonstrates how forest statistics can be successfully integrated with process-based modelling to provide long-term constraints on regional-scale forest carbon budget estimates for a European forest case-study; and (4) elucidates the combined effects of land-use and climate changes on the present-day and future terrestrial carbon balance over Europe for four illustrative scenarios - implemented by four general circulation models - using a comprehensive description of different land-use types within the framework of LPJ-DGVM.</p> <p>This study presents a way to assess and reduce uncertainty in process-based terrestrial carbon estimates on a regional scale. The results of this study demonstrate that simulated present-day land-atmosphere carbon fluxes are relatively well constrained, despite considerable uncertainty in modelled net primary production. Process-based terrestrial modelling and forest statistics are successfully combined to improve model-based estimates of vegetation carbon stocks and their change over time. Application of the advanced model for 77 European provinces shows that model-based estimates of biomass development with stand age compare favourably with forest inventory-based estimates for different tree species. Driven by historic changes in climate, atmospheric CO₂ concentration, forest area and wood demand between 1948 and 2000, the model predicts European-scale, present-day age structure of forests, ratio of biomass removals to increment, and vegetation carbon sequestration rates that are consistent with inventory-based estimates. Alternative scenarios of climate and land-use change in the 21^st century suggest carbon sequestration in the European terrestrial biosphere during the coming decades will likely be on magnitudes relevant to climate mitigation strategies. However, the uptake rates are small in comparison to the European emissions from fossil fuel combustion, and will likely decline towards the end of the century. Uncertainty in climate change projections is a key driver for uncertainty in simulated land-atmosphere carbon fluxes and needs to be accounted for in mitigation studies of the terrestrial biosphere.</p> / <p>Kohlenstoffspeicherung in terrestrischen Ökosystemen reduziert derzeit die Wirkung anthropogener CO₂-Emissionen auf das Klimasystem, indem sie die Wachstumsrate der atmosphärischer CO₂-Konzentration verlangsamt. Die heutige terrestrische Kohlenstoffbilanz wird wesentlich von Klima- und Landnutzungsänderungen beeinflusst. Diese Einflussfaktoren werden sich auch in den kommenden Dekaden auf die terrestrische Biosphäre auswirken, und dabei möglicherweise zu einer positiven Rückkopplung zwischen Biosphäre und Klimasystem aufgrund von starken Bodenkohlenstoffverlusten in einem wärmeren Klima führen. Quantitative Abschätzungen der Wirkung dieser Einflussfaktoren - sowie der mit ihnen verbundenen Unsicherheit - auf die terrestrische Kohlenstoffbilanz sind daher sowohl für das Verständnis des Erdsystems, als auch für eine langfristig angelegte Klimaschutzpolitik relevant.</p> <p>Um regionale Kohlenstoffbilanzen in die Zukunft zu projizieren, sind Modelle erforderlich, die die wesentlichen Prozesse des terrestrischen Kohlenstoffkreislaufes beschreiben. Die vorliegende Arbeit (1) analysiert die parameterbasierte Unsicherheit in Modellergebnissen eines der führenden globalen terrestrischen Ökosystemmodelle (LPJ-DGVM) im Vergleich mit unterschiedlichen ökosystemaren Messgrößen, sowie unter Klimawandelprojektionen, und erweitert damit bereits vorliegende Studien zu anderen Aspekten der Modelunsicherheit; (2) diskutiert unter theoretischen und experimentellen Aspekten verschiedene Hypothesen über die altersbedingte Abnahme des Waldwachstums, und implementiert die vielversprechenste Hypothese in das Model; (3) zeigt für eine europäische Fallstudie, wie Waldbestandsstatistiken erfolgreich für eine verbesserte Abschätzung von regionalen Kohlenstoffbilanzen in Wäldern durch prozessbasierten Modelle angewandt werden können; (4) untersucht die Auswirkung möglicher zukünftiger Klima- und Landnutzungsänderungen auf die europäische Kohlenstoffbilanz anhand von vier verschiedenen illustrativen Szenarien, jeweils unter Berücksichtigung von Klimawandelprojektionen vier verschiedener Klimamodelle. Eine erweiterte Version von LPJ-DGVM findet hierfür Anwendung, die eine umfassende Beschreibung der Hauptlandnutzungstypen beinhaltet. </p> <p>Die vorliegende Arbeit stellt einen Ansatz vor, um Unsicherheiten in der prozessbasierten Abschätzung von terrestrischen Kohlenstoffbilanzen auf regionaler Skala zu untersuchen und zu reduzieren. Die Ergebnisse dieser Arbeit zeigen, dass der Nettokohlenstoffaustausch zwischen terrestrischer Biosphäre und Atmosphäre unter heutigen klimatischen Bedingungen relativ sicher abgeschätzt werden kann, obwohl erhebliche Unsicherheit über die modelbasierte terrestrische Nettoprimärproduktion existiert. Prozessbasierte Modellierung und Waldbestandsstatistiken wurden erfolgreich kombiniert, um verbesserte Abschätzungen von regionalen Kohlenstoffvorräten und ihrer Änderung mit der Zeit zu ermöglichen. Die Anwendung des angepassten Modells in 77 europäischen Regionen zeigt, dass modellbasierte Abschätzungen des Biomasseaufwuchses in Wäldern weitgehend mit inventarbasierten Abschätzungen für verschiede Baumarten übereinstimmen. Unter Berücksichtigung von historischen Änderungen in Klima, atmosphärischem CO₂-Gehalt, Waldfläche und Holzernte (1948-2000) reproduziert das Model auf europäischer Ebene die heutigen, auf Bestandsstatistiken beruhenden, Abschätzungen von Waldaltersstruktur, das Verhältnis von Zuwachs und Entnahme von Biomasse, sowie die Speicherungsraten im Kohlenstoffspeicher der Vegetation. Alternative Szenarien von zukünftigen Landnutzungs- und Klimaänderungen legen nahe, dass die Kohlenstoffaufnahme der europäischen terrestrischen Biosphäre von relevanter Größenordnung für Klimaschutzstrategien sind. Die Speicherungsraten sind jedoch klein im Vergleich zu den absoluten europäischen CO₂-Emissionen, und nehmen zudem sehr wahrscheinlich gegen Ende des 21. Jahrhunderts ab. Unsicherheiten in Klimaprojektionen sind eine Hauptursache für die Unsicherheiten in den modellbasierten Abschätzungen des zukünftigen Nettokohlenstoffaustausches und müssen daher in Klimaschutzanalysen der terrestrischen Biosphäre berücksichtigt werden.</p>

Title from second page of PDF document. Includes bibliographical references.

Submitted by Caroline Periotto (carol@ufscar.br) on 2016-10-03T12:28:31Z No. of bitstreams: 1 DissGGS.pdf: 4226904 bytes, checksum: 7820ca73512d90a4017fd20d94821cd9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-10T18:49:56Z (GMT) No. of bitstreams: 1 DissGGS.pdf: 4226904 bytes, checksum: 7820ca73512d90a4017fd20d94821cd9 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-10T18:50:07Z (GMT) No. of bitstreams: 1 DissGGS.pdf: 4226904 bytes, checksum: 7820ca73512d90a4017fd20d94821cd9 (MD5) / Made available in DSpace on 2016-10-10T18:50:18Z (GMT). No. of bitstreams: 1 DissGGS.pdf: 4226904 bytes, checksum: 7820ca73512d90a4017fd20d94821cd9 (MD5) Previous issue date: 2015-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / The use of Escherichia coli cultures to obtain heterologous proteins poses as a successful application of biotechnology for the production of drugs and enzymes. However, the stress caused by the synthesis of the recombinant protein as well as by the culture conditions may trigger physiological responses on the cell and also cause changes in the cell morphology, impacting on the rheology of the culture broth. This study aimed to evaluate changes in cell morphology, on the rheology of the broth and the effect of different temperatures and inducers in the cellular responses during recombinant protein production by E. coli in batch cultures. Five medium cell density cultures were conducted with two clones of rE. coli, using defined medium containing glycerol as main carbon source and different inducers (IPTG and lactose), at two different temperatures (37°C and 27°C). All experiments were performed in 5 L bench bioreactor, equipped with a monitoring and control system. Samples were collected throughout the experiments and rheological parameters were measured using a concentric cylinder rheometer. The morphological characteristics of the microorganism were also examined by optical microscopy associated with image analysis. The concentrations of cellular suspension (optical density and dry cell weight) as well as of sugars and metabolites (HPLC), the plasmid retention (subculture on plates with and without antibiotic), the concentration of viable cells (colony forming units), the production of recombinant protein (densitometry), the concentration of soluble proteins (Bradford protein assay) and the presence of polysaccharide in the broth (phenol–sulfuric method) were also monitored. It was found that broths, initially behaving as Newtonian fluids, undergo a change in rheological behavior during the growth phase, exhibiting a Bingham fluid behavior. During the induction phase, the consistency index and the initial shear stress seemed to follow the changes in cell concentration or the stress caused by the protein synthesis, respectively. In addition, the intensity of the variation of both rheological parameters seemed to be dependent upon the used inducer. The morphology analysis showed that rheological properties could not be explained by changes in cell length. The correlation between the cell concentration (measured by dry-weight method) and the optical density when lactose was employed as inducer, due to galactose accumulation within the cells as a result of the inability of the bacteria to metabolize this carbon source. The presence of a small amount of PspA and genetic material in the culture broth was probably due to permeabilization and lysis of a small part of the population. Carbon recovery analysis was performed for all cultures, leading to values close do 100 % before induction, in all studied cases. After induction, a sharp decrease on the recovery was observed. However, by including the carbon present in the polysaccharide quantified in the cultivation broth, it was possible to recover all supplied carbon as biomass, CO2 and polysaccharide. Finally, the highest production of protein was obtained at 37°C when induced by IPTG, reaching 125 mgPspA/gMS. The results contribute to a deeper understanding of the heterologous proteins production by rE. coli and allow the definition of intensification strategies for protein production. / O uso de cultivos de Escherichia coli para obtenção de proteínas heterólogas tem se mostrado uma área de aplicação bem sucedida da biotecnologia para a produção de fármacos e enzimas. Contudo, o estresse provocado pela síntese da proteína recombinante e pelas condições de cultivo pode desencadear respostas fisiológicas na célula, assim como provocar mudanças na morfologia celular e na reologia do caldo de cultivo. O presente trabalho teve como objetivo principal avaliar as mudanças na morfologia celular, na reologia dos caldos e o efeito de diferentes temperaturas e indutores sobre as respostas celulares durante o processo de produção de proteínas recombinantes por rE. coli em cultivos em batelada. Foram acompanhados cinco cultivos de média densidade celular de dois clones de rE. coli, conduzidos em meio definido contendo glicerol como principal fonte de carbono e como indutores IPTG e lactose em duas temperaturas (37°C e 27°C). Todos os cultivos foram realizados em biorreator de bancada de 5 L dotado de sistema de monitoramento e controle. Durante esses cultivos, amostras foram coletadas e os parâmetros reológicos foram avaliados por meio de um reômetro de cilindros concêntricos. As características morfológicas do microrganismo foram também acompanhadas com auxílio de microscopia ótica associada a programa de análise de imagens digitalizadas. Foram ainda monitoradas a concentração celular da suspensão (por medida de densidade ótica e massa seca), a concentração de açúcares e ácidos orgânicos (por HPLC), a retenção plasmidial (repicagem em placas com e sem antibiótico), a concentração de células cultiváveis (por contagem de unidades formadoras de colônia), a produção de proteína recombinante (por densitometria), a concentração de proteína solúvel (pelo método de Bradford) e a presença de polissacarídeo no caldo (pelo método fenol sulfúrico). Verificou-se que os caldos, inicialmente newtonianos, passam por uma mudança de comportamento reológico durante a fase de crescimento, passando a se comportar como um fluido Binghamiano. Durante a fase de indução, o índice de consistência e a tensão de cisalhamento inicial tiveram respostas ligadas à concentração celular e ao estresse causado pela síntese de proteína, respectivamente, e a intensidade desta resposta dependeu do indutor usado. A análise do comprimento celular não permitiu associar as mudanças reológicas com mudanças significativas na morfologia da população durante o cultivo. Verificou-se alteração na correlação entre a concentração celular (medida pelo método da massa seca) e a densidade ótica quando lactose foi empregada como indutor, em função do acúmulo de galactose no interior das células devido à incapacidade da bactéria em metabolizar essa fonte de carbono resultante da hidrólise da lactose. Foi possível observar a presença uma pequena quantidade de PspA e de material genético no caldo de cultivo, provavelmente devido a permeabilização e lise de pequena parte da população. Contabilizou-se a recuperação do carbono para todos os experimentos, obtendo-se valores próximos de 100 % antes da indução em todos os casos. Após a indução foi verificada uma acentuada queda nessa recuperação. Porém, incluindo o carbono presente no polissacarídeo quantificado no caldo de cultivo, foi possível recuperar todo o carbono fornecido na forma de biomassa, CO2 e polissacarídeo. Por fim, a maior produção de proteína foi obtida a 37°C e induzida por IPTG, alcançando 125 mgPspA/gMS, em cultivo caracterizado pela curta duração da fase de indução (apenas 4 horas). Os resultados contribuem para ampliar a compreensão do processo de produção de proteínas heterólogas por rE. coli e permitem definir estratégias de intensificação da produção de proteína.

A produtividade dos plantios de eucalipto no Brasil apresentou ganhos significativos nas últimas décadas devido a avanços em melhoramento genético e silvicultura. Contudo, a produção de madeira representa apenas uma fração da produtividade primária bruta (GPP). Avaliar fluxos e partição de carbono (C) entre os diferentes componentes da floresta, e estudar o uso e a eficiência de uso dos recursos disponíveis é essencial para compreender os mecanismos que controlam a produtividade de plantios intensivamente manejados. O estudo quantificou os fluxos e partição de C e a eficiência de uso da luz para a produção de lenho (LUE) em 12 parcelas em um gradiente natural de produtividade, durante o sétimo ano de um plantio comercial de Eucalyptus grandis. Nessas mesmas parcelas, na escala da árvore, foram avaliadas a dominância do crescimento, produção de lenho e LUE, identificando a representatividade de árvores dominantes e suprimidas na produtividade do povoamento. O estudo do balanço de C e a aplicação da teoria da ecologia da produção em diferentes escalas objetivaram ampliar o conhecimento sobre os processos que governam a produtividade florestal. A heterogeneidade espacial dos atributos do solo e a topografia da área experimental influenciaram fortemente os fluxos componentes da GPP e sua partição, gerando um gradiente de produtividade. A produtividade de lenho variou de 554 gC m-2 ano-1 na parcela com menor GPP a 923 gC m-2 ano-1 na parcela com maior GPP. O fluxo de C para o solo variou de 497 gC m-2 ano-1 a 1235 gC m-2 ano-1 sem relação significativa com GPP. A partição do GPP para produção de lenho aumentou de 0,19 a 0,23, com tendência de aumento com o GPP (R2=0,30, p=0,07). A LUE aumentou em 66% (de 0,25 gC MJ-1 para 0,42 gC MJ-1) com a GPP, como resultado da elevação do fluxo e partição de C para produção de lenho. Ao longo do gradiente de produtividade, parcelas com alta eficiência quântica do dossel também mostraram alta LUE. A dominância do crescimento entre árvores teve forte impacto sobre a produtividade do povoamento. As 20% maiores árvores apresentaram em média 38% da biomassa de lenho e representaram 47% da produção de lenho. Características das folhas sugeriram que a maior produtividade de árvores dominantes, em relação às suprimidas, pode resultar de diferenças no controle estomático e não na capacidade fotossintética. A ecologia da produção na escala da árvore mostrou que os indivíduos dominantes produziram mais madeira por terem absorvido mais radiação e pela maior eficiência do uso da luz, comparativamente às árvores suprimidas. Em média, uma árvore suprimida cresceu 1,2 kg ano-1 de lenho, absorveu 2,9 GJ ano-1 de radiação e teve uma LUE de 0,4 g MJ-1. Já uma dominante cresceu 37 kg ano-1, absorveu 38 GJ ano-1 com mais que o dobro da eficiência (1,01 g MJ-1). Estudos sobre o balanço de carbono e ecologia da produção em diferentes escalas são essenciais para aperfeiçoar o conhecimento sobre os processos que controlam a produtividade de madeira e a fixação de carbono, e aprimorar os modelos ecofisiológicos. / The productivity of the eucalypt plantations in Brazil showed significant increase over the last decades, due to improvement in breeding and silviculture. However, wood production represents only a fraction of the gross primary production (GPP). Assessing carbon (C) fluxes and partitioning among forest components, and evaluate use and use efficiency of the available resources is essential to understand mechanisms driving productivity of intensively managed plantations. The study quantified fluxes and partitioning of C and light use efficiency for stem production (LUE) in 12 plots across a natural gradient of productivity during the seventh year of a commercial Eucalyptus grandis. Within these plots, at tree level, were evaluated growth dominance, stem production and LUE, identifying representativeness of dominant and suppressed trees to stand productivity. The study of C budget and the application of the production ecology theory at different levels aimed increase the knowledge about the processes driving forest productivity. The spatial heterogeneity of soil attributes and topography across the experimental site strongly influenced the component fluxes of GPP and partitioning, generating a gradient of productivity. Stem production ranged from 554 gC m-2 year-1 at the lowest GPP plot to 923 gC m-2 year-1 at the highest GPP plot. Total below ground carbon flux (TBCF) ranged from 497 g C m-2 year-1 to 1235 g C m-2 year-1, with no relationship to ANPP or GPP. Stem NPP:GPP partitioning ratio increased from 0.19 to 0.23 showing a trend of increase with GPP (R2=0.30, p=0.07). LUE increased by 66% (from 0.25 gC MJ-1 to 0.42 gC MJ-1) with GPP, as a result of the increased C partitioned and flux to stem NPP. Across the gradient of productivity, plots with the highest canopy quantum efficiency also showed the highest LUE. Growth dominance between trees showed a strong impact on stand productivity. The 20% larger trees accounted for 38% of stem biomass and represented 47% stem production. Leaf characteristics suggested that dominant trees were more productive, in relation to suppressed, may result in differences on stomatal control and not on photosynthetic capacity. The production ecology at tree level showed that dominant trees produced more wood by absorbing more radiation and due to higher light use efficiency, comparing to suppressed trees. On average, a suppressed tree grew 1,2 kg year-1 of stem, absorbed 2,9 GJ year-1 of radiation with a LUE of 0.4 g MJ-1. Although, a dominant grew 37 kg year-1 of stem, absorbed 38 GJ year-1 of radiation with the double of efficiency (1.01 g MJ-1). Studies regarding carbon balance and production ecology at different levels are essential to improve the knowledge on processes controlling wood production and carbon uptake, and develop ecophysiological models.

No description available.

Dans l’éventualité où l’important réservoir de carbone que représentent les tourbières venait à être déstabilisé, les impacts sur le climat planétaire pourraient être majeurs. Pourtant, les facteurs influençant les taux d’accumulation de carbone à l’échelle décennale et centennale dans les tourbières n’ont pas clairement été déterminés et les dynamiques passées et contemporaines en matière d’accumulation de carbone ont rarement été comparées pour le même site d’étude. Ce projet visait à (1) reconstruire à l’échelle fine (cm) les taux d’accumulation de carbone pour la tourbière Degerö Stormyr (Suède), (2) identifier les principaux facteurs influençant ces taux d’accumulation et (3) comparer les taux reconstruits aux flux de carbone contemporains mesurés sur le site. Deux approches méthodologiques complémentaires ont été employées : les reconstructions paléoécologiques et la modélisation. Les principales conclusions de ce mémoire sont les suivantes : (1) les taux apparents d’accumulation de carbone sont principalement liés aux conditions hydroclimatiques dans l’acrotelme, mais sont influencés par la composition végétale de la tourbe dans le catotelme. (2) Les taux réels d’accumulation de carbone pour la période récente (≈ 130 dernières années) sont semblables au bilan écosystémique net de carbone mesuré sur le site. (3) La comparaison entre les dynamiques récentes et à plus long terme suggère que Degerö Stormyr a séquestré davantage de carbone au cours des dernières décennies. Les résultats de ce mémoire soulignent l’importance d’étudier les facteurs influençant les taux d’accumulation de carbone pour différentes échelles temporelles et suggèrent que l’accent doit être mis sur l’accumulation de carbone à l’échelle décennale et centennale. / In the event that the important carbon reservoir sequestered in peatlands were to be destabilized, the impacts on global climate could be major. However, the factors influencing carbon accumulation rates at decadal and centennial scale in peatlands have not yet been clearly identified and past and contemporary carbon accumulation dynamics of the same study site have rarely been compared. This project aimed to (1) reconstruct fine scale (cm) carbon accumulation rates for the Degerö Stormyr peatland (Sweden), (2) identify the key factors influencing accumulation rates and (3) compare the reconstructed rates to modern carbon fluxes measured at the site. Two complementary methodological approaches were used: paleoecological reconstructions and modelling. The main conclusions of this thesis are that: (1) Apparent rates of carbon accumulation are mainly related to hydroclimatic conditions in the acrotelm, but are influenced by the vegetation composition of the peat in the catotelm. (2) True rates of carbon accumulation for the recent period (≈ last 130 years) are similar to the net ecosystem carbon balance measured on site. (3) The comparison between recent and long-term carbon accumulation dynamics suggests that Degerö Stormyr has sequestered more carbon over the past decades. The results of this thesis highlight the importance of studying factors influencing carbon accumulation rates at different time scales and suggest that emphasis should be placed on decadal and centennial scales.

Made available in DSpace on 2017-07-25T19:29:41Z (GMT). No. of bitstreams: 1 josiane.pdf: 937524 bytes, checksum: fac9597a15355333fedce082a07f433d (MD5) Previous issue date: 2006-05-17 / The objective of this study was to quantify the changes of the total carbon (C) and total nitrogen (N) stock, and the variation of the C pool’s in monthly soil samples, and the C balance and C sequestration rates provoked by the soil tillage systems. The soil samples were accomplished in a long term experiment implanted in 1988, in the experimental station of Fundação ABC located in Ponta Grossa city, Center-South area of the Paraná State. The soil tillage systems were comprised: a) Conventional Tillage (CT); b) Minimum Tillage (MT); c) No-tillage with chisel plow (NTCP) each three years; and d) No-tillage – Continuous (NTC). Soil samples for each treatments were obtained by digging 3 profiles of 20-cm x 50-cm (surface area) x 50-cm deep for each replicate, and collected from three depths (0,0- to 2.5- cm, 2.5- to 5-cm, 5- to 10-cm). In the samples collected in October of 2003, May of 2004 and November of 2004, the total organic carbon (TOC) and the total nitrogen in all of the depths was measured. The particle size fractionation was accomplished, separating the soil in fractions in the size of 2000 - 210 Wm, 210 - 53 Wm and <53 Wm. In all these fractions TOC was determined. The treatments had significant effects on TOC and TN contents and pools. The total C and N stock in NTC was superior to the other systems demonstrating larger maintenance of C in the soil. The larger concentration of C was observed in the 210 to 53 Wm particle size fraction in the NTC. In the 2000 - 210 Wm fraction of the 0,0-2,5 cm layer were observed larger changes in the C stock due to the management systems in the samples at all long year. The greatest change was accomplished to CT. In NTP, the stock of C was larger in all soil samples, indicating that the maintenance of the cultural residues in the associated surface protection of the aggregates allows larger accumulation of C. Although the C stock in the particle size fraction <53 Wm not to present significant differences among the management systems, and was observed the C migration of the coarse fractions (210-53 and 2000-210 Wm) to the recalcitrant particle size fraction, indicating a continuous C flow. The C balance model adjusted for the local conditions revealed that the oxidation rate acted by K2 is inferior to the simulations accomplished by other authors, demonstrating the importance of the local conditions. With this model, the minimum amount of crop residues to maintain NTC system in steady-state was 8,05 Mg ha-1 year-1 while in the PC treatment it won't be possible to reach the balance with the amount of crop residues placed in this long term experiment, being a deficient system. / RESUMO Este estudo teve por objetivo quantificar as alterações provocadas pela adoção de sistemas de manejo do solo sobre o estoque total de carbono (C) e nitrogênio (N), a variação do estoque do C nas épocas de coleta, o balanço de C e as taxas de seqüestro de C. As coletas do solo foram realizadas em um experimento de longa duração, implantado em 1988, na estação experimental da Fundação ABC em Ponta Grossa, Meso Região Centro-Oriental do Estado do Paraná. Os sistemas de manejo do solo foram avaliados: a) Preparo convencional (PC), Preparo mínimo (PM), plantio direto escarificado (PDE) e plantio direto permanente (PDP). As amostras foram coletadas em 12 épocas com intervalos mensais e nas profundidades de 0,0-2,5; 2,5-5,0 e 5,0-10 cm de profundidade. As amostras deformadas foram coletadas em mini-trincheiras nas camadas de 0,0-2,5 e 2,5-5,0 cm e na camada de 5,0- 10,0 cm com o auxílio do trado. Nas amostras coletadas em outubro de 2003, maio de 2004 e novembro de 2004 foi determinado o carbono orgânico total (COT) e o nitrogênio total (NT) em todas as profundidades amostradas. Nas amostras coletadas mensalmente foi realizado o fracionamento granulométrico da matéria orgânica, separando o solo em frações no tamanho 2000 – 210 Wm, 210 – 53 Wm e < 53 Wm. Em todas estas frações foi determinado o COT. O estoque total de C e N no PDP foi superior aos demais sistemas de manejo demonstrando maior manutenção do C no solo. O estoque de C nas frações granulométricas apresentaram diferenças significativas entre as camadas amostradas, observando-se maior concentração de C na fração 210 a 53 Wm do PDP. Na fração 2000 – 210 Wm da camada de 0,0-2,5 cm observaram-se maior alteração no estoque de C devido aos sistemas de manejo durante as épocas de coleta, sendo a maior amplitude de variação atribuída ao PC. No PDP, o estoque de C foi maior em todas as épocas de coleta indicando que a manutenção dos resíduos culturais na superfície associada à proteção dos agregados permite maior acúmulo de C. Embora o estoque de C na fração < 53 Wm não apresentar diferenças significativas entre os sistemas de manejo, observou-se uma migração do C das frações mais grosseiras (210-53 e 2000-210 Wm) para esta fração mais recalcitrante, indicando um fluxo contínuo de C. O modelo de balanço de C proposto por Henin e Dupuis (1945) e ajustado para as condições locais revelou que a taxa de oxidação representada pelo K2 é inferior às simulações realizadas por outros autores, demonstrando a importância das condições locais. Com este modelo, a quantidade mínima de resíduos culturais para manter sistema PDP em equilíbrio foi de 8,05 Mg ha-1 ano-1 enquanto no PC não será possível atingir o equilíbrio com a quantidade de resíduos culturais aportada, sendo um sistema deficitário.

Made available in DSpace on 2017-07-25T19:29:43Z (GMT). No. of bitstreams: 1 Ademir Oliveira Ferreira.pdf: 1294842 bytes, checksum: 8d7036f6aefa0cf3c549b0c63029e109 (MD5) Previous issue date: 2009-07-13 / Decrease in soil organic carbon (SOC) content of the surface layer into deeper layers indicates the occurrence of the stratification in the profile due to continuous C addition of crop residues enriching the soil surface layer. The objective of this study was: in Chapter 3 the relationship of stratification (RE) of C of the soil organic matter (SOM) pools can be an indicator of C sequestration in no-tillage soils? In the chapter 4 the tensile strength of aggregates is affected by the C content of Pedosequence of Latosol with medium and clay texture? in Chapter 5 which is the C balance and the amount of crop residue needed to maintain a stable C balance in a Latosol with a medium and clay texture? The experimental design was a completely randomized 2x2x2 factorial with 12 treatments. Treatments consisted of: a) an Oxisol (Red Latosol) with medium and clayey texture, b) two soil sampling periods (T1 and T2) with one year interval between them, and c) two soil sampling depths (0-5 and 5-20 cm). The soil attributes assessed were: the separation of water stable aggregates classes (19-8, 8-4, 4-2, 2-1, 1-0,5 and 05-0,25 mm), particulate organic carbon (POC), total particulate nitrogen (TPN) in the aggregate classes. Also was determined total organic carbon (TOC) and total nitrogen (NT) in the whole sample and in the aggregates sizes classes and tensile strength of aggregates. The relationship of stratification was calculated by dividing the TOC and TN values of 0-5 cm layer by the values of the same attributes of 5-20 cm layer. The C sequestration rate and the stratification ratio changes were calculated by the difference between the T2 values minus T1. The tensile strength was measured in soil aggregates and assessed in 1920 aggregates for each sampling time. Also TOC and NT content were measured in aggregates. The aggregates greater than 8 mm represented more than 70 of the total mass in both the clay and in sandy soil. The relationship of stratification ratio (0-5:5-20 cm) of SOC, TN, POC and TPN soil indicated the improvement of the surface layer. A significant linear relationship between the SR and C sequestration rate in both textural classes showed an increase in C sequestration and was more evident in LV with medium texture. The increase in TOC content resulted in decreased tensile strength (TS) of the aggregates and was more evident in the 0-5 cm layer. The TS showed inverse relationship with the soil density and was higher in the LV medium texture. The rate of sequestration of C was 0.86 for the LV with medium texture and 0.76 Mg ha-1 for the clay texture and to maintain the stable balance of C is required an input of 8.6 Mg ha-1 of crop residues. The results presented confirm the hypothesis of SR to be a sensitive indicator for the rate of carbon sequestration in no-tillage soil. Key-words: Carbon stock, Carbon balance, Carbon sequestration, Soil management systems, particulate organic carbon, particulate nitrogen. / A redução no conteúdo de carbono (C) da camada superficial em direção as camadas mais profundas do solo indica a formação da estratificação no perfil devido à adição contínua de C pelos resíduos orgânicos resultando no enriquecendo a camada superficial do solo. O objetivo deste trabalho foi avaliar os seguintes assuntos: a) a relação de estratificação (RE) de C dos compartimentos da matéria orgânica do solo (MOS) pode ser um indicador do seqüestro de C no sistema plantio direto. b) a resistência tênsil dos gregados pode ser afetada pelo conteúdo de C em Pedossequencia de Latossolo com textura média e argilosa. c) o balanço de C e a quantidade de resíduos culturais necessária para manter o equilíbrio estável de C em um Latossolo com textura média e argilosa. O delineamento experimental foi um fatorial 2x2x2 inteiramente casualizado com 12 tratamentos. Os tratamentos constituíram-se de: a) um Latossolo Vermelho com textura média e argilosa, duas épocas de amostragem do solo (E1 e E2) com um ano de intervalo entre si e duas profundidades de amostragem (0-5 e 5-20 cm). Os atributos avaliados foram: a separação das classes de agregados do tamisamento úmido (19-8, 8-4, 4-2, 2-1, 1-0,5 e 05-0,25 mm), o carbono orgânico particulado (COP), o nitrogênio total particulado (NTP) nas classes de agregado, o C orgânico total (COT) e o nitrogênio total (NT) na amostra integral e nas classes de agregados e a resistência tênsil dos agregados. A relação de estratificação (RE) foi calculada dividindo-se o valor de COT e NT da camada de 0-5 cm pelo valor na camada 5-20 cm. A taxa de seqüestro de C e a variação da relação de estratificação foram calculadas através da diferença (D) entre os valores da E2 menos o da E1. A resistência tênsil (RT) do solo foi avaliada em 1920 agregados de cada época de coleta, determinando-se, também o conteúdo de COT e NT. A classe de agregado > 8 mm representou mais de 70% da massa dos agregados tanto na textura argilosa como na arenosa. Da mesma forma, o conteúdo de COT e NT foram maiores na classe de agregado > do que 4 mm comparado as demais classes nas duas classes texturais. A relação de estratificação 5:5-20 cm) de COT, NT, COP e NTP do solo indicou a melhoria da qualidade do solo da camada superficial. A relação linear e significativa entre o DRE com a taxa de seqüestro de carbono nas duas classes texturais mostrou o aumento no seqüestro de C e foi mais evidente no LV com textura média. O incremento do conteúdo de COT resultou na diminuição da resistência tênsil (RT) dos agregados e foi mais evidente na camada de 0-5 cm. A RT apresentou relação inversa com a densidade do solo e foi superior no LV textura média. A taxa de seqüestro de C foi de 0,86 para o LV textura média e 0,76 Mg ha-1 para o textura argilosa e para manter o equilíbrio estável de C é necessário o aporte de 8,6 Mg ha-1 de resíduos culturais. Os resultados apresentados confirmaram a hipótese da RE ser um indicador sensível para a taxa de seqüestro de carbono no solo em um sistema sob plantio direto consolidado.

Les tourbières représentent 2 à 3% des terres émergées et stockent entre 10 et 25% du carbone des sols. Les tourbières sont soumises à des contraintes anthropiques et climatiques importantes qui posent la question de la pérennité de leur fonctionnement en puits de C et de leur stock. Une meilleure compréhension de ces écosystèmes est nécessaire pour déterminer les facteurs et les effets et interactions de ces facteurs sur les émissions de gaz à effet de serre (GES). Ce travail a consisté à suivre les émissions de GES et les facteurs contrôlant dans La tourbière de La Guette (Sologne) pour établir son bilan de C. En parallèle des expérimentations sur l’effet de l’hydrologie sur les flux ont été menées, enfin un suivi sur 4 sites a été réalisé pour étudier la variabilité à l’échelle journalière. Les résultats de ces travaux montrent que la tourbière de La Guette a fonctionné en source de C (-220 ± 33 gC m-2 an-1) et ce malgré un niveau de nappe élevé. Ils montrent également l’importance de la variabilité spatiale des flux estimés à l’échelle d’un site. Les expérimentations confirment l’importance de l’hydrologie et suggèrent à haut niveau de nappe d’eau des phénomènes liés au transport des gaz. Enfin l’étude de la variabilité journalière montre que la sensibilité de la respiration à la température peut être différente le jour et la nuit et que la synchronisation entre les températures du sol et la respiration peuvent améliorer la représentation de cette dernière. / Peatlands cover only 2 to 3% of the land area but store between 10 and 25% of the soil carbon. The outcome of the anthropic and climatic pressure on these ecosystems is uncertain regarding their functions and storage. A better understanding of these ecosystems is needed to determine the factors and their interactions on greenhouse gas (GHG) emission. This work consist in monitoring GHG emissions and controlling factors in a Sphagnum peatland to estimate its carbon balance. Experimentation on mesocosms were carried out to explore the effect of hydrology on the fluxes and a monitoring on 4 sites was made to study the daily variability. Results show that La Guette peatland was a carbon source (-220 ± 33 gC m-2 an-1) in spite of the high water table level. The importance of the spatial variability measured in the site was also demonstrate. The hydrology effect was confirmed by the mesocosms experiments and high water table level shows that gas transport might have an effect. Finally the study of the daily variability show that the temperature sensitivity of the respiration might be different between day and night and that synchronizing soil temperatures and respiration can improve the respiration representation.