O Brasil se destaca como o maior produtor de cana-de-açúcar do planeta. Como resultado do aumento da demanda de açúcar e etanol, cerca de 4 milhões de hectares foram convertidos em áreas de cana-de-açúcar nos últimos 10 anos. Espera-se que outros 6 milhões de hectares sejam convertidos nos próximos 10 a 20 anos para suprir a demanda nacional de derivados dessa cultura. Estas modificações podem ocasionar a emissão de gases do efeito estufa, resultantes principalmente da decomposição da matéria orgânica do solo, o que pode levar a dívida de carbono. Por outro lado, a substituição de áreas degradadas pelo cultivo da cana-de-açúcar pode acarretar no incremento dos estoques de carbono dos solos promovendo o sequestro de carbono. O principal objetivo foi proceder a metodologia proposta pelo Painel Intergovernamental de Mudanças Climáticas (IPCC) da Organização das Nações Unidas para avaliar o impacto ocasionado pela expansão do cultivo da cana-de-açúcar sobre a matéria orgânica do solo e seu resultado em emissão de CO2 ou em sequestro de carbono. O total de 142 situações de campo foram avaliadas na região Centro Sul do Brasil, onde a cana-de-açúcar vem substituindo outros usos da terra gerando o total de 6318 amostras de solo que foram analisadas considerando as três principais conversões existentes para cana-de-açúcar no país: i) Cerrado; ii) Pastagens e iii) Áreas de cultivo anual. Os resultados obtidos indicam o decréscimo dos estoques de carbono dos solos quando o cultivo de cana-de-açúcar substitui o cerrado e áreas de pastagens, e promove o incremento quando áreas de culturas anuais são substituídas. Os fatores de mudança de uso da terra referente ao período de 20 anos após a conversão de cerrado para cana-de-açúcar referente às camadas 0-30 cm, 0-50 cm e 0-100 foram respectivamente 0,79 (±0,04), 0,86 (±0,04) e 0,94 (±0,04). Para a conversão de pastagens para o cultivo de cana-de-açúcar, os fatores de impacto de mudança de uso da terra foram 0,91 (±0,04), 0,94 (±0,04) e 0,98 (±0,04), e para a conversão de áreas de cultivo anual os fatores de impacto de mudança de uso da terra foram 1,20 (±0,18), 1,20 (±0,18) e 1,21 (±0,18). O período de compensação da dívida de carbono gerada foi estimado entre 3,5 a 6,3 anos considerando a substituição de cerrado, 1 a 2 anos para áreas convertidas de pastagens e zero para áreas oriundas de cultivo anual, onde não foi observada dívida de carbono. Espera-se que os resultados gerados por este trabalho de pesquisa possam subsidiar os tomadores de decisão como forma de desenvolver políticas apropriadas para a expansão do cultivo da cana de açúcar na região Centro Sul do Brasil promovendo desenvolvimento com baixo impacto ao meio ambiente / Brazil figures as the major sugarcane producer in the world and as result of increasingly demand for sugar and ethanol about 4 millions of hectares were converted into sugarcane systems on last 10 years and others 6 millions of hectares are expected to be converted in next 10 to 20 years. This modification can increase greenhouse gas emissions as result of soil organic matter decomposition and lead to a carbon debt. The aim of this research paper was to perform the IPCC\'s Tier 2 approach to evaluate the impact of sugarcane expansion over the soil organic matter, and their results in CO2 emissions or soil carbon sequestration. A total of 142 field situations were studied in South-Central Brazil where sugarcane substituted other land uses, providing 79 comparison pairs and 6,318 soil samples that were analyzed considering three major conversions to sugarcane: i) Cerrado (Brazilian savannah); ii) Pastures; iii) Annual Cropland (maize or soybean). Our results indicate the decrease of soil carbon stocks when sugarcane overcomes cerrado and pastures, and an increase when annual cropland is replaced. The land use change impact factors after 20 years of conversion from cerrado to sugarcane for 0-30 cm, 0-50 cm and 0-100 cm layers were respectively 0.79 (±0.04), 0.86 (±0.04) and 0.94 (±0.04). For sugarcane replacing pastures the impact factors were 0.91 (±0.04), 0.94 (±0.04) and 0.98 (±0.04), and for the conversion from annual agriculture impact factors were 1.20 (±0.18), 1.20 (±0.18) and 1.21 (±0.18). The repay time for the carbon debt was estimated in 3.5 to 6.3 years considering the substitution of cerrado, 1 to 2 years for areas coming from pastures and zero for areas coming from cropland, where no carbon debt was found. We expect that results of this research paper can subsidize appropriate policies for sugarcane expansion in South-Central Brazil, promoting development with a lower environmental impact

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-03T12:07:22Z No. of bitstreams: 2 Tese - Elaine Barbosa da Silva - 2013.pdf: 5678344 bytes, checksum: ab0dee30da51890a0b884e5978e1022b (MD5) license_rdf: 21686 bytes, checksum: f60c8e7b7ea9f3ba141b21b00747aece (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-06T10:36:08Z (GMT) No. of bitstreams: 2 Tese - Elaine Barbosa da Silva - 2013.pdf: 5678344 bytes, checksum: ab0dee30da51890a0b884e5978e1022b (MD5) license_rdf: 21686 bytes, checksum: f60c8e7b7ea9f3ba141b21b00747aece (MD5) / Made available in DSpace on 2014-10-06T10:36:08Z (GMT). No. of bitstreams: 2 Tese - Elaine Barbosa da Silva - 2013.pdf: 5678344 bytes, checksum: ab0dee30da51890a0b884e5978e1022b (MD5) license_rdf: 21686 bytes, checksum: f60c8e7b7ea9f3ba141b21b00747aece (MD5) Previous issue date: 2013-02-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Cerrado biome has faced intense changes in land cover / land use since the 70´s, related to both governmental policies and private initiatives focused on the implementation of modern agricultural practices. In result, more than 50% of its original vegetation has been converted and intensively fragmented, and large-scale migration towards urban centers, in addition to others socialterritorial impacts, has occurred. Within this context, this study aims at understanding these transformations, prioritizing the spatial and temporal dimensions regarding the conversion to cultivated pastures and croplands. Considering that pastures represent the largest land use in the Cerrado, and that such occupation is the main driver behind beef production, this work specifically focused on pasture expansion, based on the spatially-explicit analysis of historical census data. Likewise, we also investigated the expansion of the Cerrado agricultural frontiers, for which four distinct areas, representing both consolidated, as well as frontiers in development were selected and mapped regarding land cover and land use changes from 1975 to 2010: a) the central-south portion of the Goiás State, representative of consolidated areas; b) the central portion of Mato Grosso, near the Cerrado – Amazon border; c) the Bahia western portion, and d) the MAPITO region, encompassing the convergence of the Maranhão, Piauí, and Tocantins states. Clearly, the proximity to major consumption centers, induced by the demand for agricultural commodities governmental incentives, drove land occupation, at different rates. Thus, the biome central-south region, occupied more rapidly with both cultivated pastures and crops, can be characterized as a traditional frontier, which anticipated the establishment of the modern agriculture. On the other hand, expansion of the agricultural frontier in more remote areas occurred more recently, according to the consolidation of the private driven and state supported commodity agriculture. It is worth of mentioning that in both consolidated and expanding frontiers, cultivated pastures dispute the more suitable lands with the crop agriculture. Although pastures are usually constrained to low fertility soils and higher slope terrains, it remains close to the consumption centers, confirming the Cerrado ability in properly accommodating both economic activities. / O bioma Cerrado tem passado por intensas mudanças na cobertura e uso da terra desde a década de 1970, desencadeadas por ação estatal e particular que visavam implantar nesse espaço a agropecuária moderna. Como consequência, ocorreu a conversão de mais de 50% de sua cobertura vegetal e a fragmentação de grande parte dos remanescentes, bem como impactos de ordem sócio-territorial, como a migração de grande parte da população rural para as cidades. A presente pesquisa busca compreender essas transformações, privilegiando a dimensão espacial e temporal da substituição da vegetação natural pelas pastagens cultivadas e pela agricultura moderna. Tendo em vista que as pastagens representam a maior classe de uso das terras no Cerrado e que a produção de bovinos está intimamente ligada à sua ocupação, busca-se compreender a expansão das pastagens cultivadas desde a década de 1970, com base na espacialização de dados censitários para todo o bioma. Outro interesse é analisar os processos de expansão da fronteira agrícola no Cerrado em áreas de uso consolidado e onde a fronteira agrícola está em franca expansão. Nesse sentido, selecionaram-se quatro áreas para as quais foram elaboradas mapas de cobertura e uso da terra entre 1975 e 2010: a) o centro-sul goiano, representativa das áreas de Cerrado com uso consolidado; b) a porção central do estado do Mato Grosso, próximo à divisa do Cerrado com a Amazônia; c) o Extremo Oeste Baiano e; b) a região do Mapito, formada pela confluência dos estados do Maranhão, Piauí e Tocantins. Evidencia-se que a distância dos grandes centros consumidores fez com que houvesse diferentes densidades de ocupação do espaço, modeladas pela demanda por produtos agropecuários e induzidas pela ação estatal. Assim, a porção centro-sul do bioma foi ocupada mais rapidamente pelas pastagens cultivadas e pela agricultura mercantil, criando aí uma fronteira agrícola tradicional, que precedeu a chegada das modernas técnicas de produção. A expansão da fronteira agrícola em espaços mais longínquos se deu mais recentemente e representa a consolidação da produção de commodities, cada vez mais conduzidas pelas ações privadas, tendo o Estado como um aliado estratégico. Consegue-se evidenciar, ainda, que tanto nas fronteiras agrícolas antigas quanto nas mais recentes as pastagens cultivadas disputam as melhores terras com a agricultura moderna, mas acaba por se conformar em áreas de solos menos férteis e mais declivosos, mantendo, por outro lado, a proximidade dos mercados consumidores, de modo que essas duas atividades se complementam na ocupação do bioma Cerrado, que mescla condições propícias ao desenvolvimento de ambas.

Submitted by Marlene Santos (marlene.bc.ufg@gmail.com) on 2014-10-13T20:57:57Z No. of bitstreams: 2 Tese - Klaus de Oliveira Abdala - 2012.pdf: 2007023 bytes, checksum: 764b97dcac1577e0294eee912c37b136 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2014-10-13T21:15:35Z (GMT) No. of bitstreams: 2 Tese - Klaus de Oliveira Abdala - 2012.pdf: 2007023 bytes, checksum: 764b97dcac1577e0294eee912c37b136 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-13T21:15:35Z (GMT). No. of bitstreams: 2 Tese - Klaus de Oliveira Abdala - 2012.pdf: 2007023 bytes, checksum: 764b97dcac1577e0294eee912c37b136 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2012-09-21 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / According to the IBGE is possible to identify four main complexes: cattle, soybeans, corn and sugar cane, responsible for the use and occupancy of approximately 97% of the soils. This thesis presents a survey of impacts on consumptive use of water resources, soils and forest remnants, from the dynamics of land use and specialization of municipalities in the state of Goiás in the complexes: Cane sugar, soybeans, corn and cattle.The results confirmed the hypothesis worked and indicated that municipal specialization in these complexes is the result of the comparative advantages of regions and that this specialization locate geographically environmental impacts analyzed.Therefore, working with the hypothesis that this specialization is the result of the exploitation of municipalities comparative advantages by competitive advantages of complexes in question.In response to questions for investigation, it was possible to identify the comparative advantages of the municipalities and the main competitive advantage of the complexes. In addition, indicators were generated from environmental risks to agriculture and a location model of these complexes as a function of the comparative advantages of the municipalities, which constitute subsidies to the establishment of institutions and public policies for regional development, the economic ecological and agro-ecological zoning and coordination between agricultural and environmental policies. / Segundo os dados do IBGE é possível identificar a presença de quatro principais complexos: bovinos, soja, milho e cana-de-açúcar, responsáveis pelo uso e ocupação de aproximadamente 95% dos solos. Esta tese apresenta o levantamento dos impactos no uso consuntivo de recursos hídricos, nos solos e no desflorestamento de remanescentes florestais, provenientes da dinâmica de uso do solo e da especialização dos municípios do estado de Goiás nos complexos cana-de-açúcar, soja, milho e bovinos. Para tanto, trabalha com a hipótese de que esta especialização é fruto da exploração das vantagens comparativas dos municípios pelas vantagens competitivas dos complexos em questão. Os resultados confirmaram a hipótese trabalhada e indicaram que a especialização municipal nos referidos complexos é fruto das vantagens comparativas das regiões e que essa especialização localiza geograficamente os impactos ambientais analisados. Como resposta às questões investigativas, foi possível identificar as vantagens comparativas dos municípios e a principal vantagem competitiva dos complexos. Além disso, foram gerados indicadores de riscos ambientais para a agricultura e um modelo de localização destes complexos como função das vantagens comparativas dos municípios, os quais constituem subsídios ao estabelecimento de instituições e formulação de políticas públicas de desenvolvimento regional, ao zoneamento agroecológico e ecológico econômico e à coordenação entre políticas agrícolas e políticas ambientais. Palavras-chave: Dinâmica de uso do solo; Estado de Goiás; Impactos ambientais, Indicadores de risco; complexos agropecuários.

O cultivo de pinhão manso é indicado como uma opção multi-propósito já que além de ser utilizado como matéria-prima para produção de biodiesel, reduzindo as emissões de gases do efeito estufa (GEE) quando este biocombustível é utilizado em substituição aos combustíveis fósseis, também pode estocar C no solo. O objetivo geral deste trabalho foi avaliar o potencial de sequestro de C no solo em cultivos de pinhão manso, bem como as alterações na qualidade da matéria orgânica do solo (MOS). Para tanto, foram quantificados os estoques de C e N do solo e os fluxos de GEE em cultivos de pinhão manso. O cálculo das taxas de sequestro de C no solo foi efetuado pela diferença entre o acúmulo de C no solo e as emissões de GEE, expressos em C equivalente (C-eq). A qualidade da MOS foi avaliada por meio da análise isotópica, fracionamento físico, índice de manejo do C (IMC), grau de humificação (HFIL) e teores de C e N na biomassa microbiana. A conversão da vegetação nativa em agroecossistemas alterou a quantidade e composição da MOS nos biomas Cerrado, Mata Atlântica e Caatinga, especialmente nas camadas superficiais. O cultivo de pinhão manso manteve os teores e estoques de C e N do solo, independentemente do uso da terra anterior (pastagem, milho ou vegetação nativa), com tendência de aumento em função do tempo de cultivo da cultura. Adicionalmente, a análise isotópica do C e N demostrou que a partir de dois anos de cultivo do pinhão manso há mudanças na composição da MOS. As contribuições do C derivado dos resíduos vegetais do pinhão manso para o C total do solo atingiram 11,5% após 7 anos de cultivo, na camada 0-30 cm. O cultivo de pinhão manso aumentou os teores de C nas frações da MOS, o IMC e os teores de C e N da biomassa microbiana em função do tempo de implantação da cultura, o que evidencia o potencial de melhoria da qualidade da MOS desse sistema a longo prazo. O HFIL foi menor nas áreas de pinhão manso em relação à vegetação nativa, indicando que os incrementos nos teores de C nessas áreas estão associados ao aumento da matéria orgânica menos estável e que a preservação seletiva não é o principal mecanismo de acumulação de C em solos sob pinhão manso. Os fatores de emissão de N2O variaram de 0,21 a 0,46% para doses inferiores à 150 kg ha-1, sendo emitidos 0,0362 Mg ha-1 ano-1 de C-eq quando aplicada a dose média usual no cultivo de pinhão manso (75 kg ha-1 ano-1). O balanço anual entre o acúmulo de C no solo e a emissão dos GEE mostrou que o cultivo de pinhão manso por 7 anos produz saldo positivo, que significou um sequestro de 0,6 Mg ha-1 ano-1 em C-eq. O presente estudo é pioneiro no Brasil e os resultados gerados nesta pesquisa são base para a análise de ciclo de vida do pinhão manso como matéria prima para a produção de biodiesel. / Jatropha cultivation is pointed as a multipurpose option whether is used for biodiesel production reducing greenhouse gases (GHG) emissions when replaces the need for fossil fuels, and also for storing C in the soil. The overall objective of this work was to evaluate the C sequestration potential of soil cultivated with Jatropha, as well as the variations in soil organic matter (SOM) quality. Therefore, C and N stocks were determined and GHG fluxes were measured in Jatropha cultivation. The difference between results from soil C storage and GHG emissions were used to calculate the C sequestration rates, defined as the C-equivalent (C-eq). SOM quality was assessed by isotopic analysis, physical fractioning, C management index (CMI), humufication degree (HFIL) and microbial C and N content. Land use change from native vegetation to agroecosystems altered the amount and composition of soil organic matter located in biomes of Cerrado, Atlantic Forest and Caatinga, especially within the surface layers. Jatropha cultivation preserved soil N and C stocks and contents, regardless of previous land use management (pasture, maize or native vegetation), proning to increase with cultivation time. Additionally, the isotopic analysis of C and N showed changes in SOM after two years with Jatropha cultivation. After 7 years of cultivation, the contribution of carbon derived from Jatropha residues to the total amount of the element stored within the 0-30 cm layer of soil reached 11.5%. The Jatropha cultivation increased the C contents in SOM, the CMI and microbial C and N contents along with cultivation time, which highlights the potential of Jatropha cultivation to improve SOM quality in the long term. HFIL of the areas with Jatropha cultivation showed lower values compared to the native vegetation. This indicates the increments of C contents for the areas planted with Jatropha are associated to the increase of the less stable portion of SOM and that the selective preservation is not the main mechanism responsible for C accumulation in soils under Jatropha cultivation. The N2O emission factors ranged from 0.21 to 0.46% for the doses up to 150 kg ha-1. Considering the average N fertilization rates applied annually in comercial Jatropha cultivation (75 kg ha-1 yr-1), the crop is responsible for the emission of 0.0362 Mg ha-1 yr-1 of C-eq. Moreover, the annual balance between soil C storage and GHG emission indicated that Jatropha cultivation for 7 years is able to contribute to the carbon sequestration accounting for 0.6 Mg ha- 1 yr-1 of C-eq stored in the soil. This study is pioneer in Brazil and the results generated in this research are basis for life cycle analysis of the Jatropha as a feedstock for biodiesel production in Brazil.

A Teoria da Transição Florestal prevê recuperação das florestas a partir de alterações no foco da economia, onde os setores terciário e secundário substituiriam o setor primário. Críticos desta hipótese afirmam que a transição ocorre por meio do deslocamento da produção agropecuária ao exterior, enquanto os países produtores passariam por uma expansão da agricultura, perdendo cobertura florestal. Outros autores refutam o argumento de que o comércio internacional seria o principal canal de ligação entre a Transição Florestal em países importadores e o avanço das fronteiras agrícolas nos países produtores. Diante da divergência dos modelos explicativos, o presente estudo busca avaliar se o comércio internacional de commodities agrícolas promove o deslocamento das áreas de desmatamento de países importadores de commodities para países exportadores. Foram analisados dados de exportações e importações de soja em grão e óleo de palma pelos principais países nesses mercados, confrontando-os com dados de variação histórica da cobertura florestal nacional entre os anos de 1990 e 2015. Os resultados apontam que o comércio internacional de commodities agrícolas opera como um canal de realocação entre o ganho de florestas em países importadores e o desmatamento em países exportadores / The Forest Transition Theory predicts that forest recover arises from changes in the focus of the economy, where the service and industry sectors replace the agriculture sector. Critics affirm that the transition occurs through the displacement of agricultural production abroad, while producing countries would undertake agriculture an expansion and lose forest cover. Other authors refute the argument that international trade would be the main linkage between the Forest Transition occurrence in importing countries and the advance of agricultural frontiers in producing countries. Considering the divergence between explanatory models, this study seeks to assess whether the international trade of agricultural commodities promotes the displacement of deforestation areas from importing countries to commodity-exporting countries. Data of exports and imports of soya bean and palm oil from the main countries in these markets were confronted to the historical variation of national forest cover between 1990 and 2015. Results point out that international trade of agricultural commodities operates as a relocation channel between forest gains in importer countries and deforestation in exporter ones

Transitional land uses produced through urbanisation continue to change the landscape and fragment ecological structures including green spaces across Europe (Nilsson et al., 2013). Green spaces offer significant benefits to humans, contributing to wellbeing and life satisfaction (Taylor, 2002). The understanding of how these unique green spaces spaces function and provide benefits to humans, and how landscape change in peri-urban contexts affects their performance, is important. The scope of this research is to contribute to an understanding of landscape fragmentation within some of Europe's polycentric urban regions, their peri-urban green spaces, and the associated impacts upon human quality of life. Two urban regional case studies, Paisley near Glasgow, Scotland, and Vantaa, near Helsinki, Finland were analysed and compared. The results indicate that humans interacting with more physically or ecologically fragmented peri-urban green spaces have higher self-reported life satisfaction levels. Though no statistically significant characteristics were apparent between life satisfaction and fragmented green space characteristics, this research was able to identify those specific structural attributes and physical characteristics of interstitial peri-urban green spaces within a polycentric region in a fragmented state that contribute to the physical, social, and psychological aspects of human wellbeing. The statistically significant eco-spatial characteristics of polycentric peri-urban interstitial green spaces that are reported to impact human wellbeing are the size, proximity, maintenance and management, and the level of greenness within its vegetation composition and setting. Overall, a spatially diverse, fragmented, peri-urban landscape whose green spaces are extensively sized, naturalistically shaped with horizontal vegetation and normal sized edges, most often parks or woodlands or forests which are integrated and physically connected to another green space which is moderately clean and somewhat safe as well as being located close to or adjacent to a heavy-trafficked road provide the most human wellbeing benefits.

L'utilisation des terres (UT) vers des pratiques agricoles non durables amplifie la dégradation et l'érosion des sols, et la perte de leur diversité microbienne. Cependant, les impacts du changement d'UT sur la structure de la communauté microbienne dans les cours d'eau adjacent restent mal compris, en particulier dans les écosystèmes tropicaux. Grâce à des expériences contrôlées et à des études in situ, j'ai évalué comment différentes pratiques agricoles et d'UT, via des processus hydrologiques, affectent la quantité et la qualité de la matière organique dissoute dans le cours d'eau et la structure de la communauté microbienne associée. Les résultats de ce travail montrent l'importance de considérer à la fois l’UT passée et présente avec les processus hydrologiques lors de l'évaluation de la diversité microbienne et des capacités métaboliques des cours d’eau. Alors que les expériences dans des conditions contrôlées (micro- et mésocosmes) ont permis de distinguer l'importance relative des ruissèlements d’eau de surface sur la structure bactérienne du milieu aquatique, l'approche in situ a permis de donner une vision intégrée de ces processus à l'échelle du bassin. Cela a mis en évidence la nécessité d'utiliser des pratiques de gestion durable d'UT si nous souhaitons atténuer les impacts sur les systèmes aquatiques en aval / Land use (LU) change towards non-sustainable agricultural practices enhances soil degradation, erosion, and the loss of soil microbial diversity. However, the impacts of LU change on in-stream microbial community structure remain poorly understood, particularly in tropical ecosystems. Through controlled experiments and in situ investigations, I assessed how different LU and agricultural practices, via hydrological processes, affect the quantity and quality of stream dissolved organic matter and associated microbial community structure. The results of this work show the importance of considering both past and present LU along with hydrological processes when assessing stream microbial diversity and metabolic capacities. While the experiments in controlled conditions (micro- and mesocosms) allowed disentangling the relative importance of direct overland flow and soil community on stream bacterial structure, the in situ approach gave an integrated view of these processes at the basin scale. This emphasizes the need to use sustainable LU management practices if we wish to mitigate off-site impacts on downstream aquatic systems

A Teoria da Transição Florestal prevê recuperação das florestas a partir de alterações no foco da economia, onde os setores terciário e secundário substituiriam o setor primário. Críticos desta hipótese afirmam que a transição ocorre por meio do deslocamento da produção agropecuária ao exterior, enquanto os países produtores passariam por uma expansão da agricultura, perdendo cobertura florestal. Outros autores refutam o argumento de que o comércio internacional seria o principal canal de ligação entre a Transição Florestal em países importadores e o avanço das fronteiras agrícolas nos países produtores. Diante da divergência dos modelos explicativos, o presente estudo busca avaliar se o comércio internacional de commodities agrícolas promove o deslocamento das áreas de desmatamento de países importadores de commodities para países exportadores. Foram analisados dados de exportações e importações de soja em grão e óleo de palma pelos principais países nesses mercados, confrontando-os com dados de variação histórica da cobertura florestal nacional entre os anos de 1990 e 2015. Os resultados apontam que o comércio internacional de commodities agrícolas opera como um canal de realocação entre o ganho de florestas em países importadores e o desmatamento em países exportadores / The Forest Transition Theory predicts that forest recover arises from changes in the focus of the economy, where the service and industry sectors replace the agriculture sector. Critics affirm that the transition occurs through the displacement of agricultural production abroad, while producing countries would undertake agriculture an expansion and lose forest cover. Other authors refute the argument that international trade would be the main linkage between the Forest Transition occurrence in importing countries and the advance of agricultural frontiers in producing countries. Considering the divergence between explanatory models, this study seeks to assess whether the international trade of agricultural commodities promotes the displacement of deforestation areas from importing countries to commodity-exporting countries. Data of exports and imports of soya bean and palm oil from the main countries in these markets were confronted to the historical variation of national forest cover between 1990 and 2015. Results point out that international trade of agricultural commodities operates as a relocation channel between forest gains in importer countries and deforestation in exporter ones

This thesis presents the findings of an investigation of the spatial and temporal distribution of soil macrofauna at multiple scales within smallholder agriforestry fields in a remote, mountainous area of western Honduras. Since 1990, smallholder farmers in the study area have switched from traditional slash-and-burn agriculture to a form of slash-and-mulch agriforestry based on cultivating maize, beans and sorghum amongst dispersed trees. The principal objective was to examine the influence of the slash-and-mulch agricultural system on soil macrofauna abundance, biomass and community composition, and relate soil macrofauna distribution patterns to environmental variables. The initial stage of the research comprised transect-based sampling of soil macrofauna and biophysical variables in four common land uses of the study area. All four land uses (secondary forest, young milpa (agriforestry), mature milpa, and pasture) supported abundant, diverse and heterogeneous soil macrofauna communities, with few notable differences in soil macrofauna distribution among land uses. The most abundant soil macrofauna taxa were termites, ants, earthworms and beetles. Of the 'explanatory' environmental variables that were measured (including land use and selected soil properties, vegetation characteristics and topographic variables), those that had the strongest relationships with soil macrofauna abundance were land use, tree density and soil organic matter content. The second stage of the research was spatially-orientated and used stratified sampling based on within-field differences in farmer-defined soil type, as well as grid-based sampling of soil macrofauna surface activity. There was substantial within-field variation in soil type and topography, which was related to distribution patterns of at least one agriculturally-important soil macrofauna taxon. Earthworm activity was higher in areas of fertile soil and lower slope positions. At a finer scale, there was a positive spatial correlation between tree distribution and earthworm casting activity. The final phase situated the biophysical research in the local socio-economic context through participant observation and interviews with farmers. The results of the three phases of the study were incorporated into an original conceptual model of the relationships among soil macrofauna and environmental variables in the study area across multiple spatial scales and along a chronosequence of land use changes. Specific pointers are provided for further research on the role of soil fauna in influencing soil structure, nutrient cycling and pest species abundance, and for further investigating local knowledge and the socio-economic and cultural drivers of land use change.

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