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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Anatomia comparada do lenho de 64 espécies arbóreas de ocorrência natural na floresta tropical amazônica no estado do Pará / Comparative wood anatomy of 64 tree species ocurring in the Amazon Rainforest in the state of Pará

Tássio Ticiano Trevizor 17 June 2011 (has links)
Os estudos da anatomia macro e microscópica do lenho como ferramenta auxiliar na taxonômia, sobretudo na identificação de espécies florestais, vêm sendo utilizados há décadas. A análise comparativa da estrutura anatômica do lenho permite a identificação de características morfológicas exclusivas das ordens, famílias, gêneros e, em muitos casos, de espécies, aumentando a gama de caracteres utilizados na descrição e identificação botânica de espécies arbóreas pela taxonomia clássica. No presente trabalho, foram utilizadas técnicas de análise comparativa e de descrição da estrutura anatômica macro e microscópica do lenho de árvores de espécies que ocorrem naturalmente na floresta tropical Amazônica nos municípios de Santarém, Mojú, Paragominas e Tailândia, no estado do Pará. Os objetivos do trabalho foram (i) caracterizar a estrutura anatômica macro e microscópica do lenho; (ii) identificar as características de valor taxonômico através de análise comparativa da estrutura anatômica do lenho; (iii) elaborar chaves de identificação das espécies pela estrutura anatômica macro e microscópica do lenho. Foram analisadas 100 amostras do lenho do tronco de árvores de 64 espécies, coletadas em 2004, pelo projeto Dendrogene/Embrapa Amazônia Oriental. A superfície das amostras do lenho foi polida com lixas e navalhas, seguindo-se a sua descrição macroscópica; lâminas histológicas do lenho foram preparadas com navalha de micrótomo de deslize, para a descrição microscópica do lenho. Os resultados possibilitaram, pela análise comparativa da estrutura anatômica do lenho, confeccionar as chaves de identificação macroscópica de 49 espécies dos 51 gêneros. Os gêneros Hymenolobium e Virola com 4 e 2 espécies, respectivamente, não puderam ser separados. A chave de identificação microscópica permitiu identificar 64 das espécies estudadas. A análise comparativa do lenho permitiu, da mesma forma, evidenciar 25 espécies com potencial para a dendrocronologia, sendo 10 e 15, com anéis de crescimento com distintos e pouco distintos, respectivamente. A aplicação da anatomia do lenho como importante ferramenta com potencial a taxonomia de espécies florestais é discutida no presente trabalho / Studies of macro and microscopic wood anatomy as an auxiliary tool in taxonomy, particularly in the identification of forest tree species, have been used for decades. Comparative analysis of the wood anatomical structure allows the identification of unique morphological characteristics of the orders, families, genera, and in many cases, species, increasing the range of characters used in the botanical description and identification of tree species by classical taxonomy. In this work, techniques were used for comparative analysis and description of the anatomical structure of macro and microscopic wood tree species, that occur naturally in the Amazon rainforest in the Santarém, Mojú Paragominas and Tailândia cities, in Pará State. The aims of the study were (i) to characterize the macro and microscopic anatomical wood structure, (ii) identify the characteristics of taxonomic value through a comparative analysis of the wood anatomical structure, (iii) prepare the keys for species identification by macroscopic and microscopic wood anatomical structure. Were analyzed 100 wood samples from 64 tree species collected in 2004, in the project Dendrogene/Embrapa Amazonia Oriental. The surface of wood samples was polished with sandpaper and knives, according to their macro description; histological wood sections were prepared with razor sliding microtome, for microscopic wood description. The results allowed for the comparative analysis of the anatomical wood structure, to produce the macroscopic identification keys to 49 species of 51 genera. The genera Hymenolobium and Virola species with 4 and 2, respectively, could not be separated. The results from comparative wood anatomy showed evidence of 25 tree species with high potential for dendrochronological studies in order to distinct tree-ring presence (10 species) and barely distinct tree-rings (15 species). The application of wood anatomy, as an important tool with the potential of forest species taxonomy is discussed in this paper.
32

Deforestation patterns and hummingbird diversity in the Amazon rainforest

Labor, Felicia January 2016 (has links)
In recent decades expanding land-use change has caused extensive deforestation of the tropical rainforestinducing large-scale transformation of the landscape patterns across the South American continent. Landscapechange is a modification process of the natural forest cover into fragments which generate various ecologicalimpacts. Habitat loss is identified to be a major threat to biodiversity, as it exposes species to the risk ofextinction. This study investigates 80 locations within tropical rainforest biomes to examine the landscape changewhich has occurred from 1993 – 2014. The intention is to identify the impacts of landscape fragmentation onhummingbird species diversity by spatial landscape analysis in GIS and regression modeling. The analysis foundthat there is no relationship between deforestation and reduction of hummingbird diversity. The results indicatethat hummingbird species are not particularly sensitive to landscape change as they have high resilience in regardto forest fragmentation. A potential threshold value of deforestation degree could be identified, up to whichhummingbird species richness increased, but locations subjected to over 40% fragmentation were estimated tohave lower hummingbird diversity. However, by using the spatial explicit biological data, the analysis indicatethat an extinction debt may exist in the landscape, and that future extinctions may be expected to occur in thefollowing decades as consequence of deforestation. Other factors may be as important determining variables forspecies richness: the spatial scale of the study, the habitat connectivity, hummingbird generalist tendencies.Conclusively, identification of the key factors of deforestation impacts on species diversity is essential for futureefficiency in conservation planning and sustainability of the tropical rainforest biodiversity.
33

Epidémiologie du paludisme chez les personnes travaillant sur des sites d’orpaillage illégal en Guyane : Quels enjeux pour la santé publique ? / Epidemiology of malaria in persons working on illegal gold mining sites in French Guiana : challenges for public health

Douine, Maylis 09 June 2017 (has links)
Introduction : Bien que les données officielles fassent état d’une diminution globale du nombre de cas de paludisme en Guyane, les orpailleurs travaillant sur les sites illégaux au cœur de la forêt amazonienne semblent très touchés par cette pathologie. L’objectif principal de cette étude était de déterminer la prévalence du paludisme dans cette population. Les objectifs secondaires évaluaient la proportion des différentes espèces plasmodiales et leur distribution géographique, le niveau de résistance des parasites aux dérivés de l’artémisinine, les connaissances attitudes et pratiques vis à vis de cette pathologie, et des données de santé de cette population. Matériel et méthodes : Les inclusions ont eu lieu sur les sites de repli des orpailleurs le long du fleuve Maroni. Après recueil du consentement éclairé, un test de diagnostic rapide du paludisme était effectué, ainsi qu’un questionnaire, un examen clinique, et un prélèvement de sang pour microscopie, PCR et tests de résistance (RSA et génotypage du gène pfK13 pour les PCR positives à Plasmodium falciparum). Résultats : De janvier à juin 2015, 421 orpailleurs ont été inclus, majoritairement des hommes (70,6%) brésiliens (93,8%), de médiane d’âge de 37 ans. La prévalence du portage de plasmodies déterminée par PCR était de 22,3% (IC95% : 18,3-26,3) à 84% asymptomatiques. Les espèces identifiées étaient principalement P. falciparum (47,9%) puis P. vivax (37,2%) avec 10,6% de coinfections. Lors du dernier accès palustre, 52,4% des orpailleurs avaient eu recours à l’automédication, majoritairement avec des dérivés de l’artémisinine (93,8%) avec une mauvaise observance (37,8%). Le fait d’être en Guyane était fortement associé à l’automédication (AOR=22,1). Le test RSA montrait un taux de survie supérieur à 1% pour un échantillon mais l’analyse du gène pfK13 ne mettait pas en évidence de mutations associées à la résistance à P. falciparum Discussion: La prévalence élevée de porteurs asymptomatiques de paludisme constitue un réservoir important pourla transmission du paludisme dans la région. L’utilisation massive de dérivés de l’artémisinine associée à une mauvaise observance sont des facteurs de risque d’émergence de résistance, ce qui entraînerait des conséquences sanitaires et économiques importantes. Avec une volonté politique, des actions sont possibles pour limiter ce risque, comme la distribution de kits d’autodiagnostic et d’auto-traitement avec une formation au niveau des sites de repli. / Introduction: Although official data show a global decrease of malaria in French Guiana, this disease often affects illegal gold miners working in the deep Amazonian forest. The main objective of this study was to evaluate the malaria prevalence in this population. The secondary objectives were to evaluate and map the proportion of Plasmodium species, to assess behavior, attitudes and practices regarding malaria in this population, to measure the artemisinin resistance level in parasites and to evaluate their general health. Material and methods: Inclusions took place at the gold miners’ resting sites, spread along the Maroni river. After recording their informed consent, a malaria rapid test was performed, as well as a questionnaire, a clinical exam and a blood sample for microscopy, PCR and resistance test (RSA and PfK13 genotyping for P. falciparum positive samples). Results: From January to June 2015, 421 gold miners were included, mainly men (sex ratio 2.4), Brazilian nationals (93.8%), with a median age of 37 years. Plasmodium prevalence using PCR was 22.3% (CI95%: 18.3 - 26.3), of whom 84% were asymptomatic. During the last malaria attack, 52.4% selfmedicated with artemisinin derivatives (93.8%) and a poor treatment adherence (37.8%). Being in French Guiana when the malaria attack occurred was strongly associated with selfmedication (AOR=22.1). One sample showed a survival rate higher than 1% in RSA test but PfK13 genotyping did not reveal any mutation in P. falciparum. Discussion: This high prevalence of asymptomatic carriers constitutes a huge reservoir for malaria transmission in the region. Massive use of artemisinin derivatives associated with poor treatment adherence are factors that may contribute to the emergence of artemisinin resistance. That would have huge sanitary and economical consequences. With political will, actions are possible to limit this risk, as the distribution of kits for self diagnosis and self-treatment with training on resting sites.
34

Epidémiologie des maladies infectieuses et épidémiques en milieu isolé Amazonien / Epidemiology of infectious disease and outbreak in amazonian remote

Mosnier, Emilie 13 June 2017 (has links)
Les études dans les régions isolées de la Guyane française sont rares. L'objectif principal de ce travail est d'analyser les principales données épidémiologiques résultant de des investigations sur les maladies infectieuses et épidémiques menées dans les centres de santé des régions isolées et frontalières de la Guyane. L’étude portant sur les personnes vivant avec le VIH a mit en évidence sur le plan spatial l'importance des zones fluviales frontalières qui constituent des zones actives de l’épidémie en termes de passage et de possible propagation mais aussi en termes de prévention, dépistage et traitement. Les investigations des épidémies de shigellose, de grippe et surtout de béribéri chez les orpailleurs soulignent le lien entre conditions de vie dégradées et problématiques de santé. La description des cas groupés de cryptosporidiose chez les enfants immunocompétents amérindiens reflètent les composantes multifactorielles des épidémies en zones isolées mettant en jeux des comportements humains spécifiques au sein d’écosystèmes tropicaux. La sévérité et la diversité des co-infections associés au besoin primaire de sécurité nutritionnelle rappellent les difficultés mais aussi l’urgence de l’adaptation des politiques de santé publiques aux populations éloignées. Enfin, l’étude menée sur le paludisme autochtone a tenté de discuter d’une nouvelle approche afin d’identifier et de traiter les infections asymptomatiques dans une zone de transmission endémique. La description des enjeux sanitaires et de l'état de santé des populations isolées dans les régions éloignées est cruciale pour la mise en œuvre d'une politique de santé optimisé en Guyane. / Public health data in isolated areas of French Guiana are scarce. However, a number of different communities live in tropical forest areas.The principal objective of this study is to analyse the main epidemiological data that have resulted from clinical practice and investigations conducted at health centres in isolated areas of French Guiana and its borders. The results of HIV studies have highlighted particular events that promote the spread of outbreaks. Illegal gold miners therefore represent a significant number of cases. The importance of specific geographical border areas in epidemic dynamics has also been demonstrated. Investigations on shigellosis, influenza and, most importantly, on thiamine deficiency outbreaks in gold miners underline that precarious conditions lead to poor health. Cryptosporidiosis outbreaks among immunocompetent children also reflect the multifactorial dynamics of infectious diseases, including human behaviour and the characteristics of tropical ecosystems. The severity and diversity of parasitic, viral and bacterial co-infection associated to the need for nutrition security indicates the complexity of delivering medical care to remote populations. Finally, a study on malaria has attempted to offer a novel approach to identifying and treating asymptomatic infections in an Amerindian endemic transmission area. A description of the health status of neglected populations in remote areas is crucial to implementing a health policy in French Guiana. Considering the importance of controlling communicable disease and the severity and range of specific illnesses, new strategies are needed and should be discussed with the communities involved.
35

L’histoplasmose chez le patient infecté par le VIH en Guyane française / Histoplasmosis among people living with HIV in French Guiana

Adenis, Antoine 21 November 2017 (has links)
L’histoplasmose est une infection fongique invasive. Elle était décrite comme une des principales infections opportunistes et une des premières causes de décès au stade SIDA en Guyane française.Plusieurs travaux scientifiques ont été menés. Classée première infection opportuniste au stade SIDA, l’incidence de l’histoplasmose était estimé à 1,5 p100 personne-années infectées par le VIH. Le nombre de cas incidents était stable à un niveau élevé et la proportion de décès précoces <10%. Avec une surincidence des cas en fin de saison sèche et début de petite saison des pluies, le principal processus menant à une maladie symptomatique était une nouvelle infection. La comparaison des cas de tuberculose et d’histoplasmose retrouvait respectivement, un profil clinique respiratoire dans un contexte inflammatoire marqué et, un profil disséminé accompagné de cytopénies et d’anomalies hépatiques chez des patients plus immunodéprimés. L’évaluation de la détection sérique de l’antigène galactomananne était pertinente pour le diagnostic de l’histoplasmose. Une redéfinition des critères de sévérité et le développement d’arguments pour une stratégie thérapeutique empirique à visée antifongique étaient proposés.Des résultats préliminaires démontraient la présence (au Suriname et au Guyana) et une incidence importante de l’histoplasmose chez les patients infectés par le VIH du Suriname. A l’échelle de l’Amérique Latine, la mortalité liée à l’histoplasmose était estimée équivalente voire supérieure à celle de la tuberculose chez les patients infectés par le VIH. L’histoplasmose y était jugée négligée, méconnue, responsable de nombreux décès évitables. / Histoplasmosis is an invasive fungal infection, known as one of the first AIDS-defining condition and AIDS-related deaths in French Guiana.Several scientific programmes were conducted. Ranked as the main AIDS-defining condition, histoplasmosis incidence was estimated at 1.5 p100 person-years HIV-infected. The high number of incident cases was stable and the proportion of early deaths was <10%. Following a significant increase in incidence between the end of the long dry season and the beginning of the short wet season, new infection might be the main pathophysiological mechanism leading to symptomatic disease in endemic areas. Comparison of tuberculosis and histoplasmosis in HIV-infected patients found a respiratory clinical picture in a context of pronounced inflammation and, a disseminated disease along with cytopenia and liver test abnormalities in individuals with greater immunosuppression, respectively. An evaluation of galactomannan antigen detection in serum was relevant for histoplasmosis diagnosis. Reframed severity criteria and arguments for an empiric strategy using antifungal therapy were proposed.Preliminary results showed the presence (in Suriname and Guyana) and a high incidence of histoplasmosis among HIV-infected patients in Suriname. In the whole Latin American region, we estimated that AIDS-related histoplasmosis deaths were similar or greater than AIDS-related tuberculosis deaths. HIV-associated histoplasmosis is in fact neglected, largely unknown and responsible for numerous avoidable deaths in Latin America.
36

Complex systems analysis of changing rainfall regimes in South America and their implications for the Amazon rainforest

Ciemer, Catrin 26 April 2019 (has links)
Das Ziel dieser Arbeit ist die systematische Untersuchung der Auswirkungen von Änderungen in der Niederschlagshäufigkeit und -menge im Amazonas sowie eine Prognose der zukünftigen Entwicklung des Regenwaldes unter den sich ändernden Bedingungen im Rahmen des Klimawandels. Die in dieser Arbeit durchgeführten Untersuchungen der Niederschlagskorrelationsmuster des südamerikanischen Monsuns basieren auf der Theorie komplexer Netzwerke und offenbaren beispielsweise den Übergang von einem geordneten zu einem ungeordneten System zu Beginn des Monsuns. Die Erweiterung der verwendeten Methoden hin zu mehrschichtigen Netzwerken wird anschließend zur Untersuchung der Ursache von Dürren im zentralen Amazonasgebiet verwendet. Ein bivariates Netzwerk aus Niederschlagsdaten und atlantischen Meeresoberflächentemperaturen zeigt, dass bestimmte Meeresregionen im tropischen Atlantik den Niederschlag im zentralen Amazonas stark beeinflussen. Die Ergebnisse dieser Arbeit zeigen, dass einer Dürre in der Regel die Entstehung eines klimatischen Dipols der Meeresoberflächentemperaturen zwischen den identifizierten Ozeanregionen vorausgeht. Aufbauend auf diesen Ergebnissen wird in dieser Arbeit erstmalig ein Frühwarnsystem für Dürren im Amazonas vorgestellt. Der Untersuchung des Einflusses von Niederschlagsvariabilität auf die Vegetation wird eine Potentiallandschaft aus Niederschlags- und Baumbedeckungsdaten im Amazonas zugrunde gelegt. Die vorliegende Studie zeigt, dass eine direkte Abhängigkeit zwischen der lokalen, langfristigen Niederschlagsvariabilität und der Resilienz des Waldes besteht. Dies bedeutet, dass stärkere jährliche Niederschlagsvariabilität zu einem Trainingseffekt der tropischen Vegetation führen kann. Bedenkt man außerdem, dass es in Zukunft im zentralen Amazonas mehr Dürren geben soll, kann es entscheidend sein, ob die Vegetation einer Region zuvor Erfahrung mit starker Niederschlagsvariabilität gemacht hat und dementsprechend angepasst ist. Um nicht nur lokale, sondern auch globale Einflüsse zu berücksichtigen, wird zum einen der Effekt einer sich verlangsamenden thermohalinen Zirkulation durch Klimaerwärmung und zum anderen der direkte Einfluss der Klimaerwärmung auf denn zentralen Amazonas Regenwald untersucht. Die Studie zeigt, dass beide Ereignisse gegensätzliche und somit sich ausgleichende Einflüsse auf die Vegetation im Amazonasgebiet haben können. Der Regenwald könnte somit stabil in Bezug auf den Klimawandel sein. Die vorliegende Dissertation Arbeit leistet auf der Basis von neu entwickelten Methoden einen wesentlichen Beitrag, um die Kenntnisse der betrachteten klimatischen und ökologischen Systeme zu vertiefen. / This thesis investigates the impact of changes in frequency and amount of precipitation in the Amazon rainforest and analyzes its development under the changing conditions due to global warming. In this context, complex network theory is utilized to investigate the South American monsoon system. The precipitation correlation structure reveals hidden features of the system, such as the transition from a disordered to an ordered monsoon system. Further developing existing network methods towards multilayer network tools allows for the investigation of the root causes for droughts in the central Amazon basin. By using a bivariate network between monthly precipitation in the central Amazon and Atlantic sea surface temperatures, distinct oceanic regions are identified to have a strong influence on central Amazonian precipitation. The formation of a climatological dipole between the northern and southern tropical Atlantic sea surface temperatures is found to precede droughts. As a result, this study is the first to give an early warning for droughts in the Amazon. To investigate the influence of rainfall variability on vegetation, a potential landscape is constructed from precipitation and Amazonian tree cover data. The resilience of the forest is found to directly depend on the local rainfall variability in the long-term past, thereby reflecting a vegetational training effect under specific environmental conditions. Considering climate change projections, this effect could be decisive for the future survival of the present rainforest vegetation state. In order to cover long-term influences of global warming, this thesis additionally investigates the effects of a slowing down of the Atlantic meridional overturning circulation and the direct influence of global warming on the southern Amazon rainforest.. It is revealed that these effects, although caused by global warming, have competitive impacts on precipitation in the Amazon basin, with a stabilizing effect of an Atlantic meridional overturning circulation slowdown on the Amazon rainforest. This dissertation provides newly developed, as well as adjusted methods to enhance our understanding of the considered climatological and vegetational systems. Together, they provide the basic tools for a further investigation of these complex systems.
37

Mecanismos da ciclagem do nitrogênio e emissão de óxido nitroso (N2O) em solos de diferentes latitudes

Souza, Viviane Figueiredo 04 September 2017 (has links)
Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2017-09-04T17:31:07Z No. of bitstreams: 1 TESE_Viviane Figueiredo Souza versão final.pdf: 1973892 bytes, checksum: 8b1ac31fbe25c8a6584e68f8e3b8ff71 (MD5) / Made available in DSpace on 2017-09-04T17:31:07Z (GMT). No. of bitstreams: 1 TESE_Viviane Figueiredo Souza versão final.pdf: 1973892 bytes, checksum: 8b1ac31fbe25c8a6584e68f8e3b8ff71 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / O nitrogênio (N) é um elemento imprescindível para todos os organismos do nosso planeta, entretanto o composto nitrogenado mais abundante, o gás dinitrogênio (N2), é assimilável apenas por poucos micro-organismos. Isso torna o N limitante, refletindo na sua disponibilização via mineralização de matéria orgânica (MO) e a nitrificação, que produzem amônio (NH4+) e nitrato (NO3-), respectivamente. Em solos, esses processos são regulados por fatores como conteúdo de MO e água no solo, pH e temperatura. Em ecossistemas florestais, tropicais e boreais, esses processos são muito relevantes e ainda pouco estudados, principalmente em áreas de floresta secundária sob influência de manejo. A mudança de uso do solo causa alterações na ciclagem e disponibilidade do N, nos fatores reguladores, e na emissão de óxido nitroso (N2O), um gás de efeito estufa. Padrões de recuperação florestal são bastante distintos entre diferentes florestas tropicais, como visto para floresta de Mata Atlântica e Amazônica, com taxas de mineralização em florestas jovens (10 anos) muito elevadas na Amazônia (20,9 μg N g-1 SWD d-1) e mais baixas na Mata Atlântica (3,2 μg N g-1 SWD d-1). Já a nitrificação teve um padrão semelhante, com baixas taxas em ambas as florestas jovens (0,6 6,8 μg N g-1 SWD d-1 na Mata Atlântica e Amazônia, respectivamente), o que indica uma ciclagem de N conservativa, evitando perdas via emissão de gás e lixiviação de NO3-. Entretanto, a emissão de N2O em área de restauração na Mata Atlântica foi maior do que na pristina (22 e 2,5 μg N2O-N g-1 SWD h-1, respectivamente) devido à maior temperatura do solo que estimula os processos microbianos produtores de N2O. Em termos de floresta pristina, a taxa de nitrificação foi bastante distinta entre a floresta de Mata Atlântica e Amazônica (0,08 e 15,9 μg N2O-N g-1 SWD h-1, respectivamente). Isso evidencia os diferentes fatores reguladores de cada região tropical, como regime de chuvas, composição vegetal, tipos de solo, etc. Em florestas boreais, foi visto que o conteúdo de MO e água do solo e o pH do solo são os principais reguladores, limitando a disponibilidade de N em florestas bem drenadas dominadas por coníferas, em comparação com florestas pouco drenadas dominadas por turfa. Dessa forma, verificamos que a mineralização e, principalmente, a nitrificação, são processos muito relevantes no controle de N, e mesmo em ecossistemas diferentes, os fatores reguladores muitas vezes são os mesmos. Isso evidencia a necessidade de mais estudos acerca da dinâmica do N nesses ambientes, principalmente em florestas em restauração / Nitrogen (N) is an essential element for all organisms; however, the most abundant nitrogen compound, dinitrogen (N2), is assimilable only by a few microorganisms. This makes N limiting, which reflects in its availability via organic matter (OM) mineralization and nitrification, which produce ammonium (NH4+) and nitrate (NO3-), respectively. In soils, these processes are regulated by factors such as OM and soil water content, pH and temperature. In forest ecosystems, tropical and boreal, these processes are very relevant and still poorly understood, especially in secondary forest previously deforested. The land use change causes alterations in cycling and availability of N, regulating factors, and emission of nitrous oxide (N2O), a greenhouse gas. Forest recovery patterns are quite distinct among different rainforests, as seen for Atlantic and Amazon rainforest, with very high levels of mineralization in young forests (10 years) in Amazonia (20.9 μg N2O-N g-1 SWD h-1) and low in the Atlantic Forest (3.2 μg N2O-N g-1 SWD h-1). Nitrification had a similar pattern between them, with low rates in both young forests (0.6 and 6.8 μg N2O-N g-1 SWD h-1 in the Atlantic and Amazon forest, respectively), indicating a conservative N cycling, avoiding losses through gas emission and NO3- leaching. However, the N2O emission in restoration area in the Atlantic Forest was higher than in pristine (22 and 2.5 μg N2O-N g-1 SWD h-1, respectively) due to the higher soil temperature, which stimulates microbial production of N2O. In terms of pristine forest, the nitrification rate was very different between the Atlantic forest and Amazonian forest (0.08 and 15.9 μg N2O-N g-1 SWD h-1, respectively), showing the different regulatory factors of each tropical region, such as rainfall regime, vegetal composition, soil types, etc. In boreal forests, OM, soil water content and soil pH were the main regulators, limiting the availability of N in conifer-dominated well-drained forests compared to peat-dominated poorly drained forests. In this way, we verified that mineralization and, mainly, nitrification are very relevant processes in the control of N, and even in extremely different ecosystems, the regulating factors are often the same. This evidences the need for more studies about N dynamics in these environments, especially in restoration forests
38

O valor econômico do carbono emitido pelo processo de desmatamento da Amazônia como instrumento de conservação florestal

Lamarca Junior, Mariano Rua 27 September 2007 (has links)
Made available in DSpace on 2016-04-26T20:48:49Z (GMT). No. of bitstreams: 1 Mariano Rua Lamarca Junior.pdf: 1290492 bytes, checksum: e6240c75f20575d90a5be2b3b05d364c (MD5) Previous issue date: 2007-09-27 / We analyse in the this work the causes of deforestation of the Legal Amazonia and the environment subject present in the public policies for the region, including the Public Forests Management Law (Law 11.284/06), approved with the goal of regulating public forests management in Brazil and promoting the sustainable development. We discuss the Kyoto Protocol´s Clean Development Mechanism (CDM) problem regarding forest conservation. Through a hypothetical scenario of zero deforestation and 100% of the not emitted carbon linked to forest conservation projects, we calculate that an economic revenue equivalent to the logging activities could be obtained, contributing to the maintenance of the climatic equilibrium because of the reduced Greenhouse Gases emissions, as well as keeping preserved the biodiversity and environment services values related to the standing forest. Nevertheless, appropriate regulations should be planned and implemented to achieve the desired goal, and the solution proposed in this work is in the convergence of the international laws regulating carbon markets and the native tropical forests protection laws / Analisamos neste trabalho as causas de desmatamento da Amazônia Legal e a questão ambiental presente nas políticas públicas para a região, incluindo a Lei de Gestão de Florestas Públicas (Lei 11.284/06), sancionada com o objetivo de regulamentar a gestão de florestas públicas no Brasil e promover o desenvolvimento sustentável. Discutimos o problema do Mecanismo de Desenvolvimento Limpo (MDL) do Protocolo de Kyoto na questão da conservação florestal. Através de um cenário hipotético de desmatamento zero e 100% do carbono não emitido vinculado a projetos de conservação florestal, calculamos que uma receita econômica equivalente à da exploração madeireira poderia ser obtida, contribuindo para a manutenção do equilíbrio climático pela reduzida emissão de Gases de Efeito Estufa, bem como mantendo preservados os valores da biodiversidade e dos serviços ambientais relacionados à floresta em pé (não derrubada). Entretanto, marcos regulatórios adequados devem ser planejados e implementados para atingir o objetivo desejado, e a solução proposta neste trabalho situa-se na convergência das leis internacionais de regulação dos mercados de carbono e das leis de proteção das florestas tropicais nativas
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¿Con o sin ancestros? Vigencia de lo ancestral en la Amazonía peruana

Mouriès, Thomas 25 September 2017 (has links)
La existencia o no de ancestros en la Amazonía indígena ha sidoobjeto de importantes debates. Sin embargo, los líderes de la región no dudan en llamar ‘ancestrales’ sus saberes, normas o territorios,en un sentido que, desde un punto de vista académico, puede parecer enigmático. «Ancestrales, pero… ¿con o sin ancestros?», preguntaría entonces, confuso, el antropólogo. En este artículo propongo aportar elementos de respuesta a estapregunta a través del caso peruano. Primero analizo cómo los líderes indígenas amazónicos, conectándose al circuito del derecho internacional, adoptan la noción jurídica de ‘posesión ancestral’ del territorio para adaptarla al ámbito político. Este planteamiento rinde cuenta de la generalización y uniformización reciente del vocablo ‘ancestral’ pero deja pendiente el problema de su eventual articulación con las cosmologías indígenas que pretende reflejar. Por eso, en la segunda parte, intento sondear sobre la pertinenciade la categoría de ‘ancestro’ en la Amazonía indígena, recordando brevemente el debate académico para ir definiendo en qué medida esta categoría puede cobrar sentido. A partir del testimonio de un experimentado líder awajún, la tercera parte permite, entonces, volver más explícitos los diferentes sentidos y planos referenciales que despliega la referencia a lo ancestral, mostrando cómo los indígenas amazónicos no solo adoptan elementos conceptuales y discursivos externos, sino que al mismo tiempo los transforman a partir de sus propias singularidades cosmológicas y perspectivas políticas. / The existence —or not— of the concept of ancestors in the indigenous Amazon has been the subject of much debate. However, regional leaders do not hesitate to call upon ‘ancestral’ knowledge, customs, or territories in the sense that, from an academic point of view, could appear enigmatic. «Ancestral, but… with or without ancestors?» is the question a confused anthropologist might ask. In this article, I propose to offer elements of a response to this question,based on a case study in Peru. First I analyze how Amazonian indigenous leaders, following international law, have adopted the legal notion of ‘ancestral possession’ of their territory to adapt it to the political sphere. This approach accounts for the recent generalization and uniformization of the term ‘ancestral’, but poses the problem of how it articulates with the indigenous cosmologies that it supposes to reflect. For this reason, I explore in the second section the pertinence of the category of ‘ancestor’ in the indigenous Amazon, briefly drawing upon the academic debate in order to define inwhat way this category takes on meaning. Based on testimony from an experienced Awajún leader, we thus return in the third section more explicitly to the different meanings and planes of reference that unfold when one uses the term ‘ancestral’, showing how Amazonian indigenous people not only adopt external conceptual elements and arguments, but also transform them based on their own cosmological singularities and political perspectives.
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Caracterização do carbono associado a horizontes espódicos profundos de solos da floresta amazônica, visando sua estabilidade / Characterization of carbon associated with deep podzolic horizons of soils from Amazon Forest, aiming their stability

Paula, Bruno Santos de 16 July 2015 (has links)
Este projeto nasceu inserido num contexto de crescentes pesquisas em direção à construção de um cabedal de conhecimento acerca das ciências ambientais que tratam e estudam a dinâmica dos reservatórios de carbono e suas contribuições para o Efeito Estufa. Extrapolações de novos mapas digitalizados de solos sugerem que os espodossolos hidromórficos da Amazônia podem estar com uma contagem de carbono subestimada em até 12,3 Pg de C e trabalhos anteriores mostram que o carbono imobilizado neste perfil pode sofrer mineralização devido ao corte na rede de drenagem ou rebaixamento do nível freático, podendo assim contribuir em grande parte para o aumento de emissão dos Gases do Efeito Estufa. Nesta circunstância, coube a este trabalho, caracterizar espectroscopicamente, a matéria orgânica estocada em profundidade em 9 perfis de solo da região de São Gabriel da Cachoeira - AM, na floresta amazônica. Foram analisadas 127 amostras em quantidade de carbono e por fluorescência induzida por laser (FIL). A partir destas análises preliminares, foi possível selecionar 12 amostras de 2 perfis para análise mais detalhada através da extração das substâncias húmicas. Foram realizadas análises para obtenção da textura destes perfis, análise dos ácidos húmicos como relação C/N, espectroscopia de infravermelho com transformada de Fourier (FTIR), RMN de 13C no estado sólido, fluorescências bidimensional e tridimensional com aplicação do método estatístico análise dos fatores paralelos (PARAFAC) e também análise dos ácidos fúlvicos como carbono orgânico total (TOC), espectroscopia na região do ultra-violeta e visível e fluorescência 3D associada ao PARAFAC. Em geral, as amostras se dividiram em 3 grupos diferentes, onde a matéria orgânica em superfície se mostrou lábil e recente, a matéria orgânica nos horizontes B húmicos se mostraram com características recalcitrantes e a matéria orgânica contida nos horizontes onde existia água livre (lençol freático), se mostraram com características diferentes, indicando não serem tão jovens quanto as em superfície, porém mais jovens do que a armazenada no Bh, devido a uma possível migração por movimentos laterais do lençol freático. A correlação entre os resultados mostrou que a textura do solo é importante para o acúmulo da matéria orgânica e conseqüentemente sua humificação. Os resultados de fluorescência corroboraram a interpretação dos dados de RMN, FTIR e textura, apontando que o Perfil 4 (mais próximo ao rio) por ter C2 maior nos horizontes intermediários, contém maior quantidade de exsudatos microbianos frescos. Para o Perfil 5, que é uma mancha de Espodossolo dentro de um Latossolo e encontra-se mais longe do rio, os fluoróforos mais representativos são oriundos de anéis aromáticos mais antigos e conseqüentemente mais humificados, devido às maiores intensidades de C1 e C3. Vale ressaltar que esta interpretação se alinha com os resultados de datação do 14C desta região. Foi notório que a humificação ocorre a partir do começo do horizonte Bh e que seu acúmulo pode ocorrer tanto nos horizontes intermediários (Bh) quanto mais os profundos (úmidos). Dessa forma, pode-se concluir que uma drenagem excessiva das bordas dos rios nesta região que acumula carbono em profundidade, poderá expor a MO guardada e estocada a longo tempo, contribuindo para o aumento da temperatura global e por conseguinte catalisando um desequilíbrio no clima da sua maior reguladora no mundo: a Floresta Amazônica. / This project was born inserted in a context of increasing research towards building knowledge about environmental science that treat and study the dynamics of carbon reservoirs and their contribution to the greenhouse. Extrapolation of new digital soil maps suggests that Amazonian hydromorphic Spodosols may be with a carbon accounting underestimated by up to 12.3 Pg of C and previous work show that the carbon fixed in this profile may suffer mineralization due to the cut in the drainage network or lowering of the water level and can contribute largely to the increased emission of greenhouse gas. In this circumstance, it was instructed to this work, the spectroscopic characterization, of the stored organic matter in depth at 9 soil profiles of São Gabriel da Cachoeira - AM, in the Amazon rainforest. 127 samples were analyzed for amount of carbon and laser-induced fluorescence (LIF). From these preliminary analyzes, it was possible to select 12 samples of 2 profiles for humic substances extraction and further detailed analysis. Analyzes were conducted to obtain the texture of these profiles, analysis of humic acids as C/N ratio, Fourier Transform Infrared Spectroscopy (FTIR), solid state 13C NMR, two and three dimensional fluorescence with applying of the Parallel factors analysis (PARAFAC) statistical method and also fulvic acid analysis as Total Organic Carbon (TOC), ultra-violet and visible region spectroscopy and 3D fluorescence associated with PARAFAC. In general, the samples were divided into 3 different groups, wherein the surface organic matter evinced labile and recent. The B humic horizons organic matter proved recalcitrant characteristics and organic matter contained in horizons which had free water (groundwater), showed different characteristic, indicating they are not so young as the surface, but younger than stored in Bh, because of possible migration by lateral movements of the water table. The correlation between the results showed that soil texture is important for the accumulation of organic matter and therefore its humification. The fluorescence results confirmed the interpretation of the NMR, FTIR and texture datas, indicating that the profile 4 (closest to the river), presenting major C2 in intermediate horizons, contains larger amount of fresh microbial exudates. To profile 5, which is a Spodosol spot within a Ferrasol and is thither from the river, the most representative fluorophores came from older aromatic rings and therefore is more humified, due to higher intensities C1 and C3. It is noteworthy that this interpretation is in accord with the results of 14C dating of samples from this region. It was clear that the humification occurs from the beginning of the Bh horizon and their accumulation can occur both in the intermediate horizons (Bh) and in deeper (wet). Thus, it can be concluded that excessive drainage of the edges of rivers in this region that collects carbon in depth, may expose the OM stored for long time, contributing to increase the overall temperature and therefore catalyzing an imbalance in the climate of the biggest regulatory of it in the world: the Amazon rainforest.

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