Complex interactions between topographic heterogeneity and steep gradients in climate and environmental conditions are commonly assumed to promote biotic diversification. Using tropical frogs as a model, I investigate the nature of these interactions that disrupt migration between populations, causing genetic divergence and speciation. I determine the role of several putative factors that affect gene flow (Euclidean distances, Least Cost Path (LCP) distances, topographic complexity, and elevation difference) and promote genetic structure (FST) between populations of three tropical Andean frog species. Moreover, I investigate, from an intraspecific perspective, whether montane frog species display on average larger genetic distances per kilometer relative to lowland species. Finally, I test if recent genetic divergence caused by topographic barriers to gene flow is paralleled by independent character systems such as acoustics and morphological traits in the high Andean frog Dendropsophus labialis. Even though the effect of geographic features on migration (and conversely, FST) was species-specific, LCP and Euclidean distances had the strongest effect on migration rate. Topographic complexity also reduced migration rate whereas elevation difference did not have an effect. I found that indeed highland species show larger genetic distances per kilometer between haplotypes than do lowland species. Also, genetic divergence is strongly associated with topographic heterogeneity, which is an intrinsic characteristic of montane regions. Finally, I found that acoustic variation in D. labialis diverges according to genealogical history, but external morphology does not follow this relationship. Stochastic processes due to genetic drift appear to be a better explanatory mechanism for the divergence in calls than adaptive variation. The strong and congruent divergence observed in acoustic and genetic characters indicates that these two groups correspond to morphologically cryptic parapatric species. Overall, the results of this study suggest some of the mechanisms that allow tropical mountains to promote intraspecific genetic divergence. The combined effect of ridges (promoting allopatric differentiation) and environmental gradients across elevation (promoting parapatric differentiation) are effective forces that are present mostly in highland biomes. Unfortunately, such biomes are critically threatened by habitat destruction and climate change, possibly more than any other biome on earth. / text

The goal of this thesis was to test the applicability of biomarker analyses to better understand the glacial stratigraphic record of the Hudson Bay Lowlands and Oak Ridges Moraine. A biomarker analysis conducted on three geologic deposits from the Hudson Bay Lowlands showed that they can be differentiated based on organic matter (OM) inputs and stage of diagenesis, relating to paleoclimate and depositional environments. In the second study, a biomarker analysis was applied to samples from ten deposits in the Oak Ridges Moraine. These deposits were differentiated based on OM inputs relating to paleovegetation. Additionally, reincorporation and post-deposition alteration led to sample heterogeneity confirming the current understanding of glacial depositional processes and environments. This thesis shows that biomarker analyses can effectively differentiate and contextualize geologic deposits based on OM inputs and stage of diagenesis. This in turn will provide a more robust understanding of the stratigraphic record.

The goal of this thesis was to test the applicability of biomarker analyses to better understand the glacial stratigraphic record of the Hudson Bay Lowlands and Oak Ridges Moraine. A biomarker analysis conducted on three geologic deposits from the Hudson Bay Lowlands showed that they can be differentiated based on organic matter (OM) inputs and stage of diagenesis, relating to paleoclimate and depositional environments. In the second study, a biomarker analysis was applied to samples from ten deposits in the Oak Ridges Moraine. These deposits were differentiated based on OM inputs relating to paleovegetation. Additionally, reincorporation and post-deposition alteration led to sample heterogeneity confirming the current understanding of glacial depositional processes and environments. This thesis shows that biomarker analyses can effectively differentiate and contextualize geologic deposits based on OM inputs and stage of diagenesis. This in turn will provide a more robust understanding of the stratigraphic record.

The repercussions of climate change are felt worldwide, but Arctic and subarctic regions, where climate warming is expected to be amplified, are especially vulnerable. An episode of mass fish mortality in the Sutton River in the Hudson Bay Lowlands (HBL) of Northern Ontario has elicited the interest of the scientific community. Several lakes were sampled over three years in an effort to better understand and document the changes that may be occurring in these lakes. This study uses sediment cores to assess the history of mercury (Hg) deposition and to assess changes occurring in autochthonous productivity in these lakes. Sediments deposited after the onset of the industrial revolution contained significantly higher concentrations of Hg, with the highest concentrations found in the most recently deposited sediments. Hg concentrations in these pristine lakes rival those of lakes in heavily urbanized areas, indicating that they are in fact subjected to atmospheric deposition of Hg. There was a large variation in [Hg] of the surface sediments of 13 lakes; underscoring the importance of in situ processes in the fate of atmospherically deposited Hg. Methylmercury (MeHg) concentrations were not correlated with total mercury concentrations (THg), demonstrating how THg is a poor predictor of MeHg; the bioaccumulative neurotoxic form of mercury. The S2 fraction of Rock-Eval® Pyrolysis, C:N ratios and ∂13C signatures were used as proxies of autochthonous carbon and all indicated that the lakes have become increasingly productive, presumably due to warmer water temperatures and longer ice-free seasons. Additionally, I use molecular techniques to detect and quantify the merA gene in the sediment; a proxy of bacterial mercury resistance involved in redox transformations. In Aquatuk, Hawley and North Raft Lakes, I observed a subsurface increase in merA genes in the sediment core, independently of a control gene and the [THg]. While I have not been able to explain the driving variables of this subsurface increase, I believe that the role of merA within remote lake sediments deserves further work. Lastly, microcosms were used to measure the production of volatile elemental mercury (Hg(0)) from surface sediments of Aquatuk Lake. I used a combination of analytical and molecular techniques to show that the production of Hg(0) is biogenic and tested the effect of nutrients, pH and ionic strength on the Hg(0) production rates. Ionic strength alone had the greatest impact on Hg(0) production rates, with increased Hg(0) production as ionic strength increases.

O setor agrícola é constantemente influenciado pelas conjunturas de mercado, as sazonalidades dos preços tanto de insumos quanto da produção afetam cada vez mais o produtor rural. O orizicultor domina as técnicas produtivas e as tecnologias, estando cada vez mais suscetível aos riscos da comercialização. Essa maior percepção dos riscos de mercado influencia diretamente sua tomada de decisão quanto à diversificação de cultivos. Nesse contexto os sistemas integrados de produção agropecuária ganham representatividade, reduzindo os riscos associados ao monocultivo de arroz, através da maior estabilidade da renda agrícola. Os objetivos deste trabalho são analisar as relações entre retorno e risco de diferentes sistemas produtivos de lavoura e pecuária, assim como sua integração; avaliar a importância relativa de cada atividade produtiva na formação da renda agrícola; criar cenários de aumentos de custos de produção e de valor da produção, avaliando seu impacto sobre os diferentes sistemas; analisar brevemente eficiência econômica, de uso da mão de obra própria e do uso da terra. Os sistemas produtivos analisados são: tradicional binômio arroz-pecuária (1), sistema pecuário (2), sistema similar ao tradicional com a inserção de soja (3), sistema mais diversificado e rotacionado no tempo (4), sistemas diversificados com menor uso da cultura do arroz (5 e 6). A análise do comportamento diferenciado dos sistemas permite a construção de relações Retorno x Risco, indicando que os sistemas 1, 3 e 4 possuem melhor relação retorno risco no cenário atual da propriedade, ou seja, possuem maior retorno, mas também maior risco, sendo recomendados para produtores menos avessos ao risco. Para produtores descapitalizados ou avessos ao risco o sistema 2 é o mais recomendado. Nas análises de sensibilidade para cenários futuros, a diversificação dos sistemas reduziu o impacto do aumento nos custos. A eficiência econômica, de uso de mão de obra e da terra, a cada ano-safra mostra as diferenças entre as atividades, sendo a pecuária a mais eficiente economicamente e ao mesmo tempo a que possui menor valor de cultivo por hectare. O arroz é a cultura dominante nos custos totais de produção por safra, já na formação do lucro total vêm perdendo espaço para a soja. Não existe, portanto, a recomendação de um sistema único, e sim a necessidade da formação de estratégias frente às condições do mercado. A interação de diferentes sistemas produtivos, dentro de uma propriedade, pode ser a resposta às mudanças do mercado no futuro. / The agricultural sector is constantly influenced by market, the seasonality of prices, of both inputs and the final product, are increasingly affecting the farmers. The rice producer mastered the production techniques and technologies, but are more and more susceptible to marketing risks. This increased perception of market risk directly influences their decision making regarding to crop diversification. In this context the integrated crop-livestock production systems gain representativity as a viable and attractive alternative, bringing benefits in the productive, environmental and economic spheres, reducing the risks associated with rice monoculture, through the greater stability of agricultural income. The aims of this study is to analyze the relations between return and risk of different production systems of agriculture and livestock, as well as their integration; evaluate the relative importance of each productive activity in the formation of agricultural income; create scenarios of increases in production costs and in the value of production, evaluating their impact on different systems; briefly analyze economic efficiency, use of labor and land. The production systems analyzed are: traditional rice-livestock binomium (1), livestock system (2), similar to traditional system with soy insert (3), more diversified system and rotated in time (4), diversified systems with lower use of rice (5 and 6). The analysis of the behavior of the systems allows the construction of Return x Risk relationships, indicating that the systems 1, 3 and 4 have better risk return relationship for the current situation of the property, ie have higher returns but also greater associated risk, being recommended for less aversive to risk producers. To decapitalized producers or more aversive to risk, System 2 is the most recommended. In sensitivity analysis to production costs the diversification reduced the impact of increased costs. Economic efficiency, use of work and soil use, for each harvest year, shows the differences between the activities, being livestock the most economically efficient and at the same time the one with lower crop value per hectare. Rice is the dominant culture in the total production costs, in the formation of the total profit, however, has been losing ground for soybeans. There is no recommendation of a single system, but the necessity of setting strategies to market conditions. The interaction of various production systems may be the answer to market changes in the future.

O setor agrícola é constantemente influenciado pelas conjunturas de mercado, as sazonalidades dos preços tanto de insumos quanto da produção afetam cada vez mais o produtor rural. O orizicultor domina as técnicas produtivas e as tecnologias, estando cada vez mais suscetível aos riscos da comercialização. Essa maior percepção dos riscos de mercado influencia diretamente sua tomada de decisão quanto à diversificação de cultivos. Nesse contexto os sistemas integrados de produção agropecuária ganham representatividade, reduzindo os riscos associados ao monocultivo de arroz, através da maior estabilidade da renda agrícola. Os objetivos deste trabalho são analisar as relações entre retorno e risco de diferentes sistemas produtivos de lavoura e pecuária, assim como sua integração; avaliar a importância relativa de cada atividade produtiva na formação da renda agrícola; criar cenários de aumentos de custos de produção e de valor da produção, avaliando seu impacto sobre os diferentes sistemas; analisar brevemente eficiência econômica, de uso da mão de obra própria e do uso da terra. Os sistemas produtivos analisados são: tradicional binômio arroz-pecuária (1), sistema pecuário (2), sistema similar ao tradicional com a inserção de soja (3), sistema mais diversificado e rotacionado no tempo (4), sistemas diversificados com menor uso da cultura do arroz (5 e 6). A análise do comportamento diferenciado dos sistemas permite a construção de relações Retorno x Risco, indicando que os sistemas 1, 3 e 4 possuem melhor relação retorno risco no cenário atual da propriedade, ou seja, possuem maior retorno, mas também maior risco, sendo recomendados para produtores menos avessos ao risco. Para produtores descapitalizados ou avessos ao risco o sistema 2 é o mais recomendado. Nas análises de sensibilidade para cenários futuros, a diversificação dos sistemas reduziu o impacto do aumento nos custos. A eficiência econômica, de uso de mão de obra e da terra, a cada ano-safra mostra as diferenças entre as atividades, sendo a pecuária a mais eficiente economicamente e ao mesmo tempo a que possui menor valor de cultivo por hectare. O arroz é a cultura dominante nos custos totais de produção por safra, já na formação do lucro total vêm perdendo espaço para a soja. Não existe, portanto, a recomendação de um sistema único, e sim a necessidade da formação de estratégias frente às condições do mercado. A interação de diferentes sistemas produtivos, dentro de uma propriedade, pode ser a resposta às mudanças do mercado no futuro. / The agricultural sector is constantly influenced by market, the seasonality of prices, of both inputs and the final product, are increasingly affecting the farmers. The rice producer mastered the production techniques and technologies, but are more and more susceptible to marketing risks. This increased perception of market risk directly influences their decision making regarding to crop diversification. In this context the integrated crop-livestock production systems gain representativity as a viable and attractive alternative, bringing benefits in the productive, environmental and economic spheres, reducing the risks associated with rice monoculture, through the greater stability of agricultural income. The aims of this study is to analyze the relations between return and risk of different production systems of agriculture and livestock, as well as their integration; evaluate the relative importance of each productive activity in the formation of agricultural income; create scenarios of increases in production costs and in the value of production, evaluating their impact on different systems; briefly analyze economic efficiency, use of labor and land. The production systems analyzed are: traditional rice-livestock binomium (1), livestock system (2), similar to traditional system with soy insert (3), more diversified system and rotated in time (4), diversified systems with lower use of rice (5 and 6). The analysis of the behavior of the systems allows the construction of Return x Risk relationships, indicating that the systems 1, 3 and 4 have better risk return relationship for the current situation of the property, ie have higher returns but also greater associated risk, being recommended for less aversive to risk producers. To decapitalized producers or more aversive to risk, System 2 is the most recommended. In sensitivity analysis to production costs the diversification reduced the impact of increased costs. Economic efficiency, use of work and soil use, for each harvest year, shows the differences between the activities, being livestock the most economically efficient and at the same time the one with lower crop value per hectare. Rice is the dominant culture in the total production costs, in the formation of the total profit, however, has been losing ground for soybeans. There is no recommendation of a single system, but the necessity of setting strategies to market conditions. The interaction of various production systems may be the answer to market changes in the future.

Between Memory and Forgetting. Observations on Funeral Rites in the South American LowlandsA detailed analysis of the empirical data concerning Amazonian mourning reveals two types of contrasting funeral treatment. While various human groups make efforts to erase all memory of their dead, others seek to maintain continuing relationship with them. Pertinent research invalidates partially the commonly held thesis of an archetypical form of mourning in the Amazonian lowlands according to which there is a radical break with their dead. The existence of the two types of treatment also invites to reflections about the production of different forms of historical memory in these societies. / Si se realiza un examen detenido de los datos empíricos sobre las formas de duelo en la Amazonía, se revelan finalmente dos tipos contrastados de tratamiento funerario. Mientras que por un lado varios grupos humanos se esfuerzan por borrar toda traza y memoria de los muertos, por otro se busca mantener una relación de continuidad con ellos. Las investigaciones realizadas invalidan en parte la tesis común aceptada según la cual la forma arquetípica del duelo en las tierras bajas pasaría por una ruptura radical con los muertos. La existencia de estos dos tipos de tratamiento invita, por otra parte, a reflexionar sobre la producción de formas diferenciadas de memoria histórica en esas sociedades.

O setor agrícola é constantemente influenciado pelas conjunturas de mercado, as sazonalidades dos preços tanto de insumos quanto da produção afetam cada vez mais o produtor rural. O orizicultor domina as técnicas produtivas e as tecnologias, estando cada vez mais suscetível aos riscos da comercialização. Essa maior percepção dos riscos de mercado influencia diretamente sua tomada de decisão quanto à diversificação de cultivos. Nesse contexto os sistemas integrados de produção agropecuária ganham representatividade, reduzindo os riscos associados ao monocultivo de arroz, através da maior estabilidade da renda agrícola. Os objetivos deste trabalho são analisar as relações entre retorno e risco de diferentes sistemas produtivos de lavoura e pecuária, assim como sua integração; avaliar a importância relativa de cada atividade produtiva na formação da renda agrícola; criar cenários de aumentos de custos de produção e de valor da produção, avaliando seu impacto sobre os diferentes sistemas; analisar brevemente eficiência econômica, de uso da mão de obra própria e do uso da terra. Os sistemas produtivos analisados são: tradicional binômio arroz-pecuária (1), sistema pecuário (2), sistema similar ao tradicional com a inserção de soja (3), sistema mais diversificado e rotacionado no tempo (4), sistemas diversificados com menor uso da cultura do arroz (5 e 6). A análise do comportamento diferenciado dos sistemas permite a construção de relações Retorno x Risco, indicando que os sistemas 1, 3 e 4 possuem melhor relação retorno risco no cenário atual da propriedade, ou seja, possuem maior retorno, mas também maior risco, sendo recomendados para produtores menos avessos ao risco. Para produtores descapitalizados ou avessos ao risco o sistema 2 é o mais recomendado. Nas análises de sensibilidade para cenários futuros, a diversificação dos sistemas reduziu o impacto do aumento nos custos. A eficiência econômica, de uso de mão de obra e da terra, a cada ano-safra mostra as diferenças entre as atividades, sendo a pecuária a mais eficiente economicamente e ao mesmo tempo a que possui menor valor de cultivo por hectare. O arroz é a cultura dominante nos custos totais de produção por safra, já na formação do lucro total vêm perdendo espaço para a soja. Não existe, portanto, a recomendação de um sistema único, e sim a necessidade da formação de estratégias frente às condições do mercado. A interação de diferentes sistemas produtivos, dentro de uma propriedade, pode ser a resposta às mudanças do mercado no futuro. / The agricultural sector is constantly influenced by market, the seasonality of prices, of both inputs and the final product, are increasingly affecting the farmers. The rice producer mastered the production techniques and technologies, but are more and more susceptible to marketing risks. This increased perception of market risk directly influences their decision making regarding to crop diversification. In this context the integrated crop-livestock production systems gain representativity as a viable and attractive alternative, bringing benefits in the productive, environmental and economic spheres, reducing the risks associated with rice monoculture, through the greater stability of agricultural income. The aims of this study is to analyze the relations between return and risk of different production systems of agriculture and livestock, as well as their integration; evaluate the relative importance of each productive activity in the formation of agricultural income; create scenarios of increases in production costs and in the value of production, evaluating their impact on different systems; briefly analyze economic efficiency, use of labor and land. The production systems analyzed are: traditional rice-livestock binomium (1), livestock system (2), similar to traditional system with soy insert (3), more diversified system and rotated in time (4), diversified systems with lower use of rice (5 and 6). The analysis of the behavior of the systems allows the construction of Return x Risk relationships, indicating that the systems 1, 3 and 4 have better risk return relationship for the current situation of the property, ie have higher returns but also greater associated risk, being recommended for less aversive to risk producers. To decapitalized producers or more aversive to risk, System 2 is the most recommended. In sensitivity analysis to production costs the diversification reduced the impact of increased costs. Economic efficiency, use of work and soil use, for each harvest year, shows the differences between the activities, being livestock the most economically efficient and at the same time the one with lower crop value per hectare. Rice is the dominant culture in the total production costs, in the formation of the total profit, however, has been losing ground for soybeans. There is no recommendation of a single system, but the necessity of setting strategies to market conditions. The interaction of various production systems may be the answer to market changes in the future.

The repercussions of climate change are felt worldwide, but Arctic and subarctic regions, where climate warming is expected to be amplified, are especially vulnerable. An episode of mass fish mortality in the Sutton River in the Hudson Bay Lowlands (HBL) of Northern Ontario has elicited the interest of the scientific community. Several lakes were sampled over three years in an effort to better understand and document the changes that may be occurring in these lakes. This study uses sediment cores to assess the history of mercury (Hg) deposition and to assess changes occurring in autochthonous productivity in these lakes. Sediments deposited after the onset of the industrial revolution contained significantly higher concentrations of Hg, with the highest concentrations found in the most recently deposited sediments. Hg concentrations in these pristine lakes rival those of lakes in heavily urbanized areas, indicating that they are in fact subjected to atmospheric deposition of Hg. There was a large variation in [Hg] of the surface sediments of 13 lakes; underscoring the importance of in situ processes in the fate of atmospherically deposited Hg. Methylmercury (MeHg) concentrations were not correlated with total mercury concentrations (THg), demonstrating how THg is a poor predictor of MeHg; the bioaccumulative neurotoxic form of mercury. The S2 fraction of Rock-Eval® Pyrolysis, C:N ratios and ∂13C signatures were used as proxies of autochthonous carbon and all indicated that the lakes have become increasingly productive, presumably due to warmer water temperatures and longer ice-free seasons. Additionally, I use molecular techniques to detect and quantify the merA gene in the sediment; a proxy of bacterial mercury resistance involved in redox transformations. In Aquatuk, Hawley and North Raft Lakes, I observed a subsurface increase in merA genes in the sediment core, independently of a control gene and the [THg]. While I have not been able to explain the driving variables of this subsurface increase, I believe that the role of merA within remote lake sediments deserves further work. Lastly, microcosms were used to measure the production of volatile elemental mercury (Hg(0)) from surface sediments of Aquatuk Lake. I used a combination of analytical and molecular techniques to show that the production of Hg(0) is biogenic and tested the effect of nutrients, pH and ionic strength on the Hg(0) production rates. Ionic strength alone had the greatest impact on Hg(0) production rates, with increased Hg(0) production as ionic strength increases.

Enquanto o mundo discute os esforços para combater as alterações climáticas globais, reconhece-se cada vez mais o papel vital das florestas na manutenção do bem-estar ecológico, social, econômico e cultural. Reafirma-se a importância da definição dos direitos de propriedade (posse e uso) sobre as florestas que pode determinar o seu destino. Para muitos países, as políticas de gestão de florestas combinam vários modos de acesso e gestão como i) áreas protegidas; ii) concessões florestais com critérios de gestão baseados em desempenho; iii) a devolução de áreas de florestas para as comunidades tradicionais e povos indígenas que farão sua gestão.O maior desafio é cumprir o planejado e implantar os diversos modos de gestão florestal para alcançar os objetivos sociais, econômicos e ambientais previstos face à pressão dos interesses econômicos internos e externos. A concessão de florestas é a forma dominante de gestão em quase todos os países da África Central e Ocidental. Ela também é o tipo dominante de exploração de florestas na Ásia (Malásia, Indonésia, Papua-Nova Guiné e Camboja). Na segunda metade dos anos 90, com o forte apoio de projetos de cooperação multilateral e de ONGs internacionais, a Bolívia introduziu a concessão florestal como um modo de conceder direitos de posse e uso sobre florestas. No Brasil, após duas tentativas fracassadas, o governo aprovou sua nova lei de gestão de florestas públicas em 2006. Bolívia e Brasil têm muito em comum em relação aos conflitos fundiários e desafios para impor novas regras relativas à maneira como as florestas podem ser exploradas nas suas regiões amazônicas, principalmente. Este trabalho de investigação centra-se sobre os principais obstáculos enfrentados pelas autoridades florestais bolivianas e brasileiras para implantar as concessões florestais na escala inicialmente prevista. O desenvolvimento do trabalho demandou a mobilização de duas correntes teórico-metodológicas. Por um lado, buscou-se um mapeamento dos modos pelos quais os indivíduos e grupos se apropriam e formulam regras para gerir porções de florestas. Por outro lado, a abordagem teórica da sociologia econômica, mais precisamente os trabalhos de Neil Fligstein e sua abordagem política-cultural, forneceu elementos para avaliar o processo de organização social da produção florestal madeireira nas duas regiões estudadas, que depende de quatro fatores: i) os direitos de propriedade, ii) as estruturas de governança, iii) as regras de troca e iv) as concepções de controle. A abordagem política-cultural considera a participação dos atores sociais como governos, empresas e consumidores, entre outros, e os incentivos para ações de cooperação com base nos laços cognitivos que os ligam. O estudo centrou-se na região amazônica de cada país: nas terras baixas bolivianas e, no Brasil, na região da rodovia Cuiabá-Santarém (BR-163). Isto porque estas regiões são os principais alvos para implantação de concessões florestais. Mostra-se neste estudo que sob um cenário de confusão fundiária, no qual há batalhas por pedaços dos territórios florestais e onde as alianças políticas são forjadas para favorecer outros padrões de uso das terras, a aplicação de concessões florestais em grande escala pode ser inviabilizada ou ficar bastante reduzida. / As the world is preparing to scale up its efforts to combat global climate change, groups are increasingly recognizing the vital role forests play in maintaining ecological, social, economic and cultural well-being. They are beginning to affirm more that forest tenure plays a fundamental role in determining the fate of the worlds forests. In many countries, questions are raised on whether tropical forests should be publicly, commonly or privately owned. For many countries the forest management policies will likely involve a combination of: i) protected areas of sufficient size to provide habitat protection, and in a contiguous pattern; ii) forest concessions with enforceable performance-based management criteria; iii) community forests and community forest concessions managed by communities and indigenous groups. The challenge is to undertake the land use planning commitment and implementation to achieve this in the face of pressure from internal and external interests. Forest concessions of various types are the dominant form of forest tenure in almost all the forest countries of West and Central Africa. They are also the dominant types of forest tenure in Asia (Malaysia, Indonesia, Papua New Guinea, and Cambodia). In South America, Peru and Bolivia introduced forest concession as a possible tenure model in the early 90s with the strong support of international NGOs. In Brazil, after two failed attempts, the government has passed its new forest management law in 2006. Bolivia and Brazil have much in common regarding forest tenure conflicts and challenges to enforce new rules in the forestry sector. Forest concession implementation in these countries has generated many expectations and investments in law changes.This research work focuses on the main barriers faced by Bolivian and Brazilian forest authorities in implementing forest concession on the scale initially planned. The studies required a mapping of the property rights regimes over forest and forest resources as well as a theoretical approach of economic sociology. This approach, which provides elements to evaluate the process of social market construction, is dependent upon four essential factors: property rights, governance structures, rules of exchange and conceptions of control. The political-cultural approach emphasizes the historic perspective of the markets to understand the role of dominant groups and challengers in action arenas. It also considers the participation of social actors like governments, firms and consumers, among others, and their incentives for cooperative actions based on the cognitive ties that bind them. This empiric study focused on each countrys geographically-delimited regions of Amazon: in the Bolivian lowlands region and in the Brazilian Cuiabá-Santarém Highway (namely BR-163). Thats because they are the main targets for forest concession implementation. We show in this study that under a tenure uncertainty scenario, in which there are battles for territorial pieces and political alliances are forged that prefer other land use (and forests uses also) patterns the forest concessions implementation on a large scale will be jeopardized in these territories.