Forest-cover in the tropics is changing rapidly due to indiscriminate removal of timber from many localities. The main focus of the study is to develop an operational tool for monitoring biomass and carbon pool of tropical forest ecosystems. The method was applied to a test site of Bangladesh. The research used Landsat ETM+, Landsat TM and IRS pan images of 2001, 1992 and 1999 respectively. Geometrically corrected Landsat ETM+ imagery was obtained from USGS and adjusted to the field using GPS. Historical images were corrected using image-to-image registration. Atmospheric correction was done by modified dark object subtraction method. Stratified sampling design based on the remote sensing image was applied for assessing the above-ground biomass and carbon content of the study area. Field sampling was done during 2002-2003. Dbh and height of all the trees inside the sample plots were measured. Field measurement was finally converted to carbon content using allometric relations. Three different methods: stratification, regression and k-nearest neighbors were tested for combining remote sensing image information and field-based terrestrial carbon pool. Additional field sampling was conducted during 2003-2004 for testing the accuracy. Finally regression method was selected. The amount of carbon released and sequestrated from the ecosystem was estimated. The application of the developed method would be quite useful for understating the terrestrial carbon dynamics and global climate change.

Réduire la déforestation dans les pays tropicaux est un des principaux défis pour la communauté internationale dans le cadre du processus de négociations de la Convention Cadre des Nations Unies sur le Changement Climatique (CCNUCC). En effet, la déforestation est la seconde source d'émissions de gaz à effets de serre, juste derrière les émissions industrielles. Depuis 2005, un nouvel instrument international pour réduire les émissions de carbone liées à la déforestation tropicale est en négociation à la CCNUCC. Ce mécanisme, appelé REDD+ (Réduction des Emissions liées à la Déforestation et Dégradation des forêts) repose sur un système de compensation financière des pays en développement pour leurs efforts en termes de déforestation évitée. Cependant, la mise en œuvre du mécanisme REDD+ à l'échelle nationale et internationale soulève de nombreux problèmes méthodologiques et rencontre de nombreux obstacles. Le but de la thèse est double. Dans une première partie, une description et une analyse du mécanisme REDD+ est réalisée. Dans une deuxième partie, de nouvelles perspectives concernant le design du mécanisme REDD+ et sur sa mise en œuvre sont offertes, en se basant sur trois essais rédigés en format article. Le premier essai propose un modèle de théorie des jeux reflétant le processus de négociation Nord-Sud du mécanisme REDD. Il étudie les conditions régissant le partage de fonds entre les pays en développement et leurs impacts sur l'efficacité du système d'incitations. Le deuxième essai utilise un modèle en économétrie de panel pour différencier des comportements nationaux de déforestation selon la dotation relative en forêts de chaque pays. Le troisième essai s'intéresse à la mise en œuvre du mécanisme REDD+, en comparant les résultats de deux programmes de paiement pour services environnementaux pour deux types de gouvernements. Le modèle développé dans cet essai est ensuite testé dans le contexte de la déforestation en Indonésie, grâce à une base de données fournie par l'ONG Conservation International. / Curbing deforestation in tropical countries is one of the main current challenges for international community in the United Nations Framework Convention on Climate Change. Indeed, deforestation is the second leading cause of greenhouse gas emissions just behind industrial emissions. Since 2005, a new instrument to slow down CO2 emissions from tropical deforestation is under negotiations at the UNFCCC. This mechanism, called REDD+ (for Reducing Emissions from Deforestation and forest Degradation) is supported by a simple principle: it consists to reward developing countries for their efforts to avoid deforestation. However, the national and international implementations of REDD+ raise lot of methodological questions and meet several hurdles. The aims of the thesis are twofold. First, it proposes a description and an analysis of the REDD+ mechanism. Second, it is composed by three essays, which raise some questions about REDD+ design and implementation, in order to offer new perspectives on this mechanism. The first essay develops a game-theoretic bargaining model, simulating the on-going negotiation process over the REDD+ mechanism. It shows that the conditions under which developing countries are left to bargain over the allocation of the global forest fund may lead to an ineffective system of incentives. The second essay used a panel data analysis to reveal contrasted deforestation behaviors of tropical countries according to their relative endowment in forest cover. The aim of the third essay offered an illustration of REDD+ implementation, comparing the outcomes in terms of avoided deforestation and utility of two payments for environmental services designs for two types of governments. The model developed in this article is applied in the Indonesian context of deforestation, thanks to a database supplied by the NGO Conservation International.

Nas últimas décadas as mudanças climáticas foram evidenciadas pelo aumento da temperatura global, diminuição dos estoques de carbono terrestres, associados ao aumento nas emissões de gases de efeito estufa (GEE). A floresta Amazônica é o maior bioma tropical do mundo e desenvolve serviços ambientais estratégicos no planeta. Entretanto, há mais de duas décadas que o desmatamento na Amazônia impulsiona as emissões globais de GEE, diminuindo o armazenamento de carbono do solo com alterações na dinâmica nas populações microbianas e nos ciclos biogeoquimicos pela mudança de uso da terra. O objetivo desse estudo foi avaliar as alterações temporais dos atributos químicos do solo, quantificar as emissões de CO2, CH4 e N2O e verificar as alterações na estrutura bacteriana do solo após o corte e queima de vegetação nativa na Amazônia. O estudo foi desenvolvido em área de vegetação nativa no norte do estado de Rondônia, região sul da Amazônia no Brasil. A área de estudo consistiu-se de quatro hectares, onde foi realizado o corte e queima em 2,25 hectares. Foram realizadas amostragens para avaliação da fertilidade do solo e estoques de carbono (C) e nitrogenio (N) nas profundidades de 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40-50, 50-60, 60-80 e 80-100 cm. As coletas foram realizadas em vegetação nativa e aos 2, 30, 60, 90, 120, 240 e 365 dias após corte e queima. Foram determinados os atributos pH, Al, H+Al, Ca, Mg, K, P, C, N e calculados os valores de soma de bases, CTC, V % e m %. As coletas para quantificar as emissões dos GEE foram realizadas simultaneamente na área de vegetação nativa e no hectare central da área de corte e queima aos 19, 31, 48, 61 e 81 dias após corte e 2 , 4, 6, 8, 15, 31, 45, 61, 88, 122, 153, 180, 240 e 350 dias após queima, com amostragens aos 0, 20, 40 e 60 minutos. Os atributos microbiológicos do solo foram avaliados pela técnica de T-RFLP com amostragens realizadas simultaneas nas duas áreas, aos 32 e 62 dias após o corte e aos 2, 15, 30, 45, 60, 90, 120, e 360 dias após queima da biomassa vegetal. Foi verificado rápido aumento da fertilidade do solo e diminuição da acidez e teores de Al+3 após a queima, entretanto esse efeito foi pouco persistente, retornando ao status inicial do solo após um ano. Houve redução de 30 % nos estoques de C e N do solo no final do estudo, evidenciando os efeitos deletérios da mudança do uso da terra nos atributos químicos do solo. Foi registrado redução de 50 % das emissões de CO2 equivalente após o corte, comparada à vegetação nativa e reduções nas emissões de GEE de 35 % após um ano de estudo. Verificou-se na camada superficial, alterações significativas na estrutura da comunidade bacateriana do solo em decorrência do impacto do fogo e das alterações nos atributos químicos em função da deposição superficial de cinzas no solo, entretanto não foi verificada alterações significativa nas camadas abaixo de 5 cm. Este estudo forneceu importantes informações para o entendimento dos impactos e as alterações causadas pelo processo de conversão florestal tropical pelo corte e queima de vegetação nativa na Amazônia. / In recent decades, climate change has been evidenced by the increase in global temperature and the decrease in terrestrial carbon stocks, associated with an increase in greenhouse gas (GHG) emissions. The Amazon rainforest is the largest tropical biome in the world and develops strategic environmental services on the planet. However, for more than two decades, deforestation in Amazon has driven global GHG emissions, reducing soil carbon storage with changes in microbial populations dynamics and in biogeochemical cycles due to land use change. The objective of this study was to evaluate the temporal alterations of soil chemical attributes, quantify CO2, CH4 and N2O emissions and verify changes in soil bacterial structure, due to the slash and burn of the native vegetation in Amazon. The study was developed in an area of native vegetation in the north of Rondônia state, southern region of Amazon in Brazil. The study area consisted of 4 hectares, where it was cut and burned in 2.25 hectares. Samples were collected to evaluate soil fertility and carbon (C) and nitrogen (N) stocks at the depths of 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40- 50, 50-60, 60-80 and 80-100 cm. These samples were collected in native vegetation at 2, 30, 60, 90, 120, 240 and 365 days after cutting and burning. The attributes pH, Al, H + Al, Ca, Mg, K, P, C, N were determined and the values of base sum, CEC, base saturation and aluminum saturation were calculated. The samples to quantify GHG emissions were carried out simultaneously in the native vegetation area and in the central hectare of the cutting and burning area at 19, 31, 48, 61 and 81 days after cutting and 2, 4, 6, 8, 15, 31, 45, 61, 88, 122, 153, 180, 240 and 350 days after burning, with samples at 0, 20, 40 and 60 minutes. The microbiological attributes of the soil were evaluated by T-RFLP technique with simultaneous samplings in the two areas, at 32 and 62 days after cutting and at 2, 15, 30, 45, 60, 90, 120, and 360 days after plant biomass burning. A rapid increase in soil fertility and a decrease in acidity and Al+3 contents after burning were verified, however this effect was not persistent, returning to the initial soil status after one year. There was a 30 % reduction in soil C and N stocks at the end of the study, evidencing the deleterious effects of land use change on soil chemical attributes. Also, a 50 % reduction in CO2 emissions after cutting, compared to native vegetation and, a 35 % reduction in GHG emissions after one year of study, were observed. We verified in the surface layer, significant alterations in the soil bacteria structure due to the fire impact and the changes in the chemical attributes, such as surface deposition of ashes. However, we did not verified significant changes in the layers lower than 5 cm. Our study provided important information for understanding the impacts and changes of the tropical forest conversion process by slash and burning native vegetation in Amazon.

Nas últimas décadas as mudanças climáticas foram evidenciadas pelo aumento da temperatura global, diminuição dos estoques de carbono terrestres, associados ao aumento nas emissões de gases de efeito estufa (GEE). A floresta Amazônica é o maior bioma tropical do mundo e desenvolve serviços ambientais estratégicos no planeta. Entretanto, há mais de duas décadas que o desmatamento na Amazônia impulsiona as emissões globais de GEE, diminuindo o armazenamento de carbono do solo com alterações na dinâmica nas populações microbianas e nos ciclos biogeoquimicos pela mudança de uso da terra. O objetivo desse estudo foi avaliar as alterações temporais dos atributos químicos do solo, quantificar as emissões de CO2, CH4 e N2O e verificar as alterações na estrutura bacteriana do solo após o corte e queima de vegetação nativa na Amazônia. O estudo foi desenvolvido em área de vegetação nativa no norte do estado de Rondônia, região sul da Amazônia no Brasil. A área de estudo consistiu-se de quatro hectares, onde foi realizado o corte e queima em 2,25 hectares. Foram realizadas amostragens para avaliação da fertilidade do solo e estoques de carbono (C) e nitrogenio (N) nas profundidades de 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40-50, 50-60, 60-80 e 80-100 cm. As coletas foram realizadas em vegetação nativa e aos 2, 30, 60, 90, 120, 240 e 365 dias após corte e queima. Foram determinados os atributos pH, Al, H+Al, Ca, Mg, K, P, C, N e calculados os valores de soma de bases, CTC, V % e m %. As coletas para quantificar as emissões dos GEE foram realizadas simultaneamente na área de vegetação nativa e no hectare central da área de corte e queima aos 19, 31, 48, 61 e 81 dias após corte e 2 , 4, 6, 8, 15, 31, 45, 61, 88, 122, 153, 180, 240 e 350 dias após queima, com amostragens aos 0, 20, 40 e 60 minutos. Os atributos microbiológicos do solo foram avaliados pela técnica de T-RFLP com amostragens realizadas simultaneas nas duas áreas, aos 32 e 62 dias após o corte e aos 2, 15, 30, 45, 60, 90, 120, e 360 dias após queima da biomassa vegetal. Foi verificado rápido aumento da fertilidade do solo e diminuição da acidez e teores de Al+3 após a queima, entretanto esse efeito foi pouco persistente, retornando ao status inicial do solo após um ano. Houve redução de 30 % nos estoques de C e N do solo no final do estudo, evidenciando os efeitos deletérios da mudança do uso da terra nos atributos químicos do solo. Foi registrado redução de 50 % das emissões de CO2 equivalente após o corte, comparada à vegetação nativa e reduções nas emissões de GEE de 35 % após um ano de estudo. Verificou-se na camada superficial, alterações significativas na estrutura da comunidade bacateriana do solo em decorrência do impacto do fogo e das alterações nos atributos químicos em função da deposição superficial de cinzas no solo, entretanto não foi verificada alterações significativa nas camadas abaixo de 5 cm. Este estudo forneceu importantes informações para o entendimento dos impactos e as alterações causadas pelo processo de conversão florestal tropical pelo corte e queima de vegetação nativa na Amazônia. / In recent decades, climate change has been evidenced by the increase in global temperature and the decrease in terrestrial carbon stocks, associated with an increase in greenhouse gas (GHG) emissions. The Amazon rainforest is the largest tropical biome in the world and develops strategic environmental services on the planet. However, for more than two decades, deforestation in Amazon has driven global GHG emissions, reducing soil carbon storage with changes in microbial populations dynamics and in biogeochemical cycles due to land use change. The objective of this study was to evaluate the temporal alterations of soil chemical attributes, quantify CO2, CH4 and N2O emissions and verify changes in soil bacterial structure, due to the slash and burn of the native vegetation in Amazon. The study was developed in an area of native vegetation in the north of Rondônia state, southern region of Amazon in Brazil. The study area consisted of 4 hectares, where it was cut and burned in 2.25 hectares. Samples were collected to evaluate soil fertility and carbon (C) and nitrogen (N) stocks at the depths of 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, 40- 50, 50-60, 60-80 and 80-100 cm. These samples were collected in native vegetation at 2, 30, 60, 90, 120, 240 and 365 days after cutting and burning. The attributes pH, Al, H + Al, Ca, Mg, K, P, C, N were determined and the values of base sum, CEC, base saturation and aluminum saturation were calculated. The samples to quantify GHG emissions were carried out simultaneously in the native vegetation area and in the central hectare of the cutting and burning area at 19, 31, 48, 61 and 81 days after cutting and 2, 4, 6, 8, 15, 31, 45, 61, 88, 122, 153, 180, 240 and 350 days after burning, with samples at 0, 20, 40 and 60 minutes. The microbiological attributes of the soil were evaluated by T-RFLP technique with simultaneous samplings in the two areas, at 32 and 62 days after cutting and at 2, 15, 30, 45, 60, 90, 120, and 360 days after plant biomass burning. A rapid increase in soil fertility and a decrease in acidity and Al+3 contents after burning were verified, however this effect was not persistent, returning to the initial soil status after one year. There was a 30 % reduction in soil C and N stocks at the end of the study, evidencing the deleterious effects of land use change on soil chemical attributes. Also, a 50 % reduction in CO2 emissions after cutting, compared to native vegetation and, a 35 % reduction in GHG emissions after one year of study, were observed. We verified in the surface layer, significant alterations in the soil bacteria structure due to the fire impact and the changes in the chemical attributes, such as surface deposition of ashes. However, we did not verified significant changes in the layers lower than 5 cm. Our study provided important information for understanding the impacts and changes of the tropical forest conversion process by slash and burning native vegetation in Amazon.

Um das 1,5°C Ziel zu verhindern, müssen bis 2020 die globalen anthropogenen CO2 Emissionen Sektor-übergreifend ihren Spitzenwert erreichen und bis 2050 auf Netto-Null-Emissionen sinken. Der AFOLU Sektor hat einen Anteil von 23% an den globalen Treibhausgasemissionen (THGE). Neben der Möglichkeit THGE zu vermeiden, bietet die Implementierung von Klimaschutzmitigation auch Synergien um die Ernährungssicherheit, Nährstoff- und Wassereffizienz zu verbessern sowie Landdegradation umzukehren. Eine kritische Bedeutung hat die Abholzung von tropischen Waldflächen durch die mehr als ein Drittel der Emissionen im Bereich des AFOLU entsteht. Vor diesem Hintergrund werden vorliegend, mit Fokus auf die Abholzung in der tropischen Zone, die indirekten Auslöser der THGE innerhalb des AFOLU untersucht. Diese Auslöser werden zunächst auf einer globalen Skala analysiert, wobei die Rolle der Variabilität von Preisveränderungen international gehandelter Waren und weiterer sozio-ökonomischer Indikatoren auf regionale Waldumwandlungsprozesse betrachtet wird. Anschließend analysiert diese Arbeit den Aspekt des Waldverlustes im Zusammenhang mit politischer Instabilität und bewaffneten Konflikten. Zudem werden regionale Lösungen zur Mitigation in weiteren Sektoren adressiert. Insbesondere wird die Möglichkeit zur THGE-Einsparung in silvopastoralen Systemen untersucht um das Zusammenspiel zwischen intensiver Viehbewirtschaftung und der Kohlenstofffixierung besser zu verstehen. Darüber hinaus werden regionale Lösungen mit Hilfe von Basisorganisationen bzw. gemeindebasierten Initiativen (CBI) zur THGE-Einsparung in den Bereichen Energie, Nahrungsmittel, Transport und Abfall erforscht. Diese Arbeit liefert vielfältige Beiträge zum Verständnis der indirekten Auslöser von Abholzung und den damit verbundenen THGE innerhalb der tropischen Zone, sowie zur Förderung lokaler Lösungen für die sektorübergreifende THG-Minderung. / Global anthropogenic CO2 emissions from different sectors must peak in 2020 and reach net zero by 2050 in order to reach the 1.5°C target. The AFOLU sector represents 23% of global greenhouse gas (GHG) emissions. In addition to its mitigation potential, the implementation of solutions in this sector also holds the synergistic potential of enhancing climate change adaptation, improving food security, nutrient and water efficiency, and reverting land degradation. Tropical deforestation is of particular importance within the AFOLU sector, representing over a third of its emissions. Against this backdrop, this thesis examines the underlying drivers of GHG emissions in the AFOLU sector, with a particular emphasis on tropical deforestation. These drivers are explored, firstly, at a global scale by addressing the role that changes in price of internationally-traded commodity products and other socio-economic variables exert on regional forest conversion. Secondly, this work examines the relationship between tree cover loss and a very under-researched driver of tropical deforestation, namely extreme political instability and armed conflict. Motivated by the urgency of climate change impacts, this thesis also explores local solutions for climate change mitigation across different sectors. In particular, the GHG mitigation role of silvopastoral systems, a type of agroforestry system, is examined to further understand the interplay between livestock intensification and carbon sequestration. In addition, more broad, local-scale solutions are examined across the energy, food, transport, and waste sectors by addressing the GHG mitigation potential of grassroots organizations, also known as community-based initiatives (CBIs). This thesis provides manifold contributions, not only to further understand some of the underlying drivers of deforestation and associated GHG emissions in the tropics, but also towards the advancement of local solutions for GHG mitigation across sectors.

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