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Le couvert forestier dans le sud chilien représente un enjeu environnemental majeur. La forêt native, intégrée à l’Ecorégion Valdivienne (35°S–48°S), fait partie de ces écosystèmes ayant la plus haute priorité de conservation dans le monde. L’application du Decreto-Ley 701 en 1974 généra l’expansion de monocultures de pins et d’eucalyptus dans le sud chilien. L’intensification des pratiques sylvicoles, combinée à la substitution des écosystèmes forestiers natifs, remet en question leur soutenabilité à court et moyen terme. Cette étude cherche à appréhender et à anticiper la dynamique des plantations forestières à plusieurs échelles spatiales et temporelles afin d’identifier les enjeux futurs d’occupation du sol. Dans un premier temps, l’utilisation de données satellitales à moyenne résolution MODIS a permis de détecter et de quantifier les coupes forestières et les forêts stables de la 8ème Région du Bío-Bío au sud continental de la 10ème Région de Los Lagos. Le recours aux images LANDSAT a, dans un second temps, fourni des éléments de précision sur le cycle de rotations des plantations industrielles à l’échelle de deux régions. Enfin, une classification multi-dates a constitué une base d’étude pour aborder les changements d’occupation et d’utilisation du sol (LUCC) dans la commune de San Juan de la Costa. Aussi, entre 1986 et 2008, la progression des monocultures au détriment de la forêt native et des autres types d’occupation du sol atteint respectivement 3 366 ha et 6 132 ha. Bien que l’identification des facteurs explicatifs combinée à l’analyse rétrospective mette en évidence une grande complexité au sein de ce système, quatre scénarii prospectifs ont pu être proposés. Ces derniers permettent d’obtenir une vision panoramique des dynamiques évolutives des plantations forestières et de la forêt native. Si les scénarii prédictif et intensif traduisent une expansion des plantations monospécifiques en 2017 et 2026, les scénarii, exploratoire et« éco-centré », apportent une vision à contre-courant, avec un regain de forêt native et un déclin des plantations à l’horizon 2035. Le croisement des scénarii établit également un degré de congruence spatialisé susceptible de fournir, dans une perspective de gestion, des informations complémentaires d’aide à la décision. / Southern Chile forest cover represents a major environmental issue. The native forest, integrated into the Valvidian Ecoregion (35°S-48°S), belongs to ecosystems with the highest conservation priority in the world. The application of the Decree Law 701 in 1974 generated the expansion of pines and eucalyptus monocultures in Southern Chile. The intensification of silvicultural practices, combined with the substitution of native forested ecosystems, reappraises their sustainability on both short and mid-term. This study wishes to apprehend and anticipate timber plantation dynamics on several spatial and temporal scales to identify tomorrow's land occupation issues. In a first phase, the use of MODIS medium-resolution remotely sensed data enables the detection and quantification of timber cutting and stable forests from the 8th region of the Bio-Bio to the continental south of the 10th region of Los Lagos. In a second phase, turning to LANDSAT images enables to specify the rotation cycle of industrial plantations on a scale of two regions. Finally, a multi-date classification is used to build a data base in order to study land use and cover changes in the municipality of San Juan de la Costa. Between 1986 and 2008, the spread of monoculture at the expense of native forest and other types of land occupation reaches respectively 3 366 ha and 6 132 ha. Even though the identification of the explanatory factors together with retrospective analysis highlights the complexity of the system, four prospective scenarios are offered. They give us a panoramic vision of the timber plantations future dynamics, as well as those of the native forest. If the predictive and intensive scenarios express an expansion of the monospecific plantations in 2017 and 2026, the exploratory and “eco-centered” scenarios bring a vision that goes against the grain, with a resurgence of native forest and a decline in plantations by 2035. The crossing of the scenarios establishes a degree of spatial congruence and brings information that can help decision-making. / La cubierta forestal en el sur de Chile representa un desafío medio ambiental mayor. El bosque nativo, ubicado en la Ecorregión Valdiviana (35°S–48°S), forma parte de ecosistemas que tienen una alta prioridad de conservación en el mundo. La aplicación del Decreto Ley 701 en 1974 provocó la expansión de monocultivos de pinos y eucaliptos en el sur chileno. La intensificación de las prácticas silvícolas, junto con la sustitución de ecosistemas forestales nativos, pone en cuestión su sustentabilidad a corto y mediano plazo. Este estudio trata de comprender y anticipar la dinámica de las plantaciones forestales en diversas escalas espaciales y temporales para así identificar desafíos de ocupación futuros. En primer lugar, el uso de datos satelitales a resolución media con MODIS ha permitido la detección y la cuantificación tanto de las cortas como de las cubiertas forestales estables desde la Octava Región del Bío-Bío al sur continental de la Décima Región de Los Lagos. El uso de imágenes LANDSAT ha permitido reconocer el ciclo de rotaciones de las plantaciones industriales a la escala de dos regiones. Finalmente, se ha establecido una clasificación multi-temporal como base para el estudio de los cambios de ocupación y de utilización de los suelos (LUCC) en la comuna de San Juan de la Costa. Así, entre 1986 y 2008, la progresión de los monocultivos en detrimento del bosque nativo y de otros tipos de ocupación del suelo alcanza 3366 ha y 6132 ha respectivamente. A pesar que la identificación de factores explicativos relacionados con el análisis retrospectivo posee una gran complejidad dentro del sistema, cuatros escenarios prospectivos han podido ser propuestos. Estos, permiten obtener una visión panorámica de la dinámica futura de las plantaciones forestales, y también del bosque nativo. Mientras que los escenarios predictivo e intensivo reflejan una expansión de las plantaciones monoespecíficas en 2017 y 2026, los escenarios exploratorio y “eco-centrado” revelan un comportamiento contrario, con una recuperación del bosque nativo y un decrecimiento de las plantaciones en 2035. El cruce de los escenarios muestra un grado de congruencia espacial capaces de proponer, en una perspectiva de gestión, informaciones complementarias de ayuda a la decisión.

Modificações da cobertura natural dos solos podem ocasionar alterações no ciclo hidrológico, que por sua vez podem impactar a disponibilidade de água. Na Bacia Hidrográfica do Rio Paraíba do Sul (BHPS) vem ocorrendo uma substituição de coberturas vegetais em função da expansão de monoculturas de eucalipto. O objetivo desta pesquisa foi verificar os impactos de ordem hidrológica sobre a disponibilidade hídrica (quali e quantitativa) no trecho paulista da BHPS, em decorrência da implantação da atividade de silvicultura de eucalipto para produção de celulose. Para isso, foi utilizado o método de Pegada Hídrica (PH) para avaliar a alocação de água da produção de madeira de floresta nativa e de eucalipto, método que vem sendo aplicado pelo setor silvícola. Foram empregados também métodos de Balanço Hídrico Climatológico, Balanço Hídrico Geral e a abordagem de Serviços Ecossistêmicos para avaliar a relação entre a água e as principais coberturas vegetais da bacia (pastagem, floresta nativa e eucalipto), de forma a permitir uma análise ampliada e integrada do comportamento hidrológico da bacia. Ao analisar os métodos empregados, observou-se que a PH de produtos avalia apenas a eficiência do uso da água, o que pode mascarar altos consumos de água em função de maior produtividade por hectare. Isto porque se obteve menor valor de PH da madeira, em m³ por tonelada para o caso do eucalipto, e maior alocação total de água, em m³ por hectare por ano, em comparação à floresta nativa. Os resultados obtidos pela análise de Balanço Hídrico Climatológico para as principais coberturas vegetais mostraram que o eucalipto apresentou maior evapotranspiração e menor excedente hídrico. Já o Balanço Hídrico Geral, analisado mensalmente, permitiu visualizar que as coberturas vegetais influenciam o serviço de provisão de água e concorrem pelo uso de água com os demais usuários da bacia (naturais e antrópicos) em períodos de menor precipitação. Por fim, concluiu-se que são necessárias medições locais para determinação de volumes de escoamento (superficial e subterrâneo), infiltração, bem como do processo de lixiviação e perdas de solo para apontar de forma mais precisa os impactos hídricos da monocultura de eucalipto. / Modifications in the natural land cover can change the hydrological cycle, which might have an impact on water availability. In the river basin of the Paraíba do Sul river (RBPS), the natural vegetation has been being replaced due to the expansion of eucalyptus monocultures. This research assessed the impacts on water availability (both qualitative and quantitative), caused by eucalyptus forestry for pulp production in the RBPS part in Sao Paulo. The water footprint (WF) method was applied to assess the water used on the cellulose production of native forest and eucalyptus, given the use of this method by the industry. Also, the Climatic Water Balance, General Water Balance methods and the Ecosystem Services approach were used in order to perform an extended and integrated analysis of the hydrological behavior of the basin. By analyzing these methods, it was found that the products WF only assesses the efficiency in water use, which can mask high water consumption with higher productivity per hectare. This because a smaller value for wood WF was observed, in m³/ton for eucalyptus, and higher total water use, in m³ per hectare per year, compared to the native forest. The results observed by the Climatic Water Balance analysis for the main vegetation cover showed that the eucalyptus presented higher evapotranspiration and smaller water surplus. The General Water Balance, analyzed on a monthly basis, showed that the vegetation has an impact on the water provision service and competes for water with other users in the basin (natural and anthropic) in periods with less precipitation. Finally, it was concluded that local measurements are required to determine the runnof volumes (superficial and subsurface), infiltration, as well as the process of leaching and soil loss in order to have a more accurate assessment of the hydrological impacts of the eucalyptus monoculture.

Le couvert forestier dans le sud chilien représente un enjeu environnemental majeur. La forêt native, intégrée à l'Ecorégion Valdivienne (35°S-48°S), fait partie de ces écosystèmes ayant la plus haute priorité de conservation dans le monde. L'application du Decreto-Ley 701 en 1974 généra l'expansion de monocultures de pins et d'eucalyptus dans le sud chilien. L'intensification des pratiques sylvicoles, combinée à la substitution des écosystèmes forestiers natifs, remet en question leur soutenabilité à court et moyen terme. Cette étude cherche à appréhender et à anticiper la dynamique des plantations forestières à plusieurs échelles spatiales et temporelles afin d'identifier les enjeux futurs d'occupation du sol. Dans un premier temps, l'utilisation de données satellitales à moyenne résolution MODIS a permis de détecter et de quantifier les coupes forestières et les forêts stables de la 8ème Région du Bío-Bío au sud continental de la 10ème Région de Los Lagos. Le recours aux images LANDSAT a, dans un second temps, fourni des éléments de précision sur le cycle de rotations des plantations industrielles à l'échelle de deux régions. Enfin, une classification multi-dates a constitué une base d'étude pour aborder les changements d'occupation et d'utilisation du sol (LUCC) dans la commune de San Juan de la Costa. Aussi, entre 1986 et 2008, la progression des monocultures au détriment de la forêt native et des autres types d'occupation du sol atteint respectivement 3 366 ha et 6 132 ha. Bien que l'identification des facteurs explicatifs combinée à l'analyse rétrospective mette en évidence une grande complexité au sein de ce système, quatre scénarii prospectifs ont pu être proposés. Ces derniers permettent d'obtenir une vision panoramique des dynamiques évolutives des plantations forestières et de la forêt native. Si les scénarii prédictif et intensif traduisent une expansion des plantations monospécifiques en 2017 et 2026, les scénarii, exploratoire et" éco-centré ", apportent une vision à contre-courant, avec un regain de forêt native et un déclin des plantations à l'horizon 2035. Le croisement des scénarii établit également un degré de congruence spatialisé susceptible de fournir, dans une perspective de gestion, des informations complémentaires d'aide à la décision.

Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2016-11-07T15:00:25Z No. of bitstreams: 1 JussiaraSJC_DISSERT.pdf: 2658778 bytes, checksum: b61a9c5bec2c4362f3e2496913b8c2ba (MD5) / Rejected by Vanessa Christiane (referencia@ufersa.edu.br), reason: corrigir on 2016-11-14T13:28:20Z (GMT) / Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2016-11-14T15:01:16Z No. of bitstreams: 1 JussiaraSJC_DISSERT.pdf: 2658778 bytes, checksum: b61a9c5bec2c4362f3e2496913b8c2ba (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-01-24T14:34:11Z (GMT) No. of bitstreams: 1 JussiaraSJC_DISSERT.pdf: 2658778 bytes, checksum: b61a9c5bec2c4362f3e2496913b8c2ba (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-01-24T14:34:24Z (GMT) No. of bitstreams: 1 JussiaraSJC_DISSERT.pdf: 2658778 bytes, checksum: b61a9c5bec2c4362f3e2496913b8c2ba (MD5) / Made available in DSpace on 2017-02-15T15:03:12Z (GMT). No. of bitstreams: 1 JussiaraSJC_DISSERT.pdf: 2658778 bytes, checksum: b61a9c5bec2c4362f3e2496913b8c2ba (MD5) Previous issue date: 2016-02-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The absence of plant diversity in agricultural cultivation systems is as extensive and alarming rate of soil degradation. In this context, the research aimed to evaluate the physical and chemical properties of the soil in relation to landscape and agricultural uses to detect which of these attributes were the most sensitive in distinguishing environments. The research was conducted in the city of Martins / RN on site Bela Vista. To characterize the environment in study opening was held three representative profiles and collected soil samples to the diagnostic horizons for physical and chemical analysis of the soil and subsequently classification. six areas were studied: maize consortium, beans and cassava (CON); monoculture of sugarcane (CAN); banana monoculture (BN); monocultures of elephant grass (CE); corn monoculture (MM) and native vegetation as reference (MN). For the study of areas, collected by 6 samples derived from compound 15 replicates for each area mentioned above, the deformed structure with layers of 0.00 to 0.10; 0.10-0.20 and 0.20-0.30 m in order to perform analyzes of the physical and chemical soil. Analyses were performed in the laboratories of Physics and Soil Fertility of the Federal Rural University of Semi-Arid. The textural classification of soils in cultivation environments textural rating ranged Characterizing the environments in profiles as textural rating ranged from sandy clay, clay, and clayish, with pH ranging from acid neutralidade.Verificou low concentrations of exchangeable cations, consequently low base saturation, considered dystrophic. As for agricultural use followed the same trend as fertility, and the grass area elephant showed higher structural quality. The soils were classified in Fluvisols in the fields of sugar cane and elephant grass, consortium, banana and corn and Udorthent the native forest. Textural classification in soil profiles varied from sandy clay, the clay (Neossolos Fluvic), clayey to very clayey (Fluvisol) and sandy clay (Udorthent). Fertility on farming uses showed acidity reactions to the natural forest areas (MN); and Consortium (CON), tending towards neutrality for elephant grass (CE), corn (MM) and Banana (BAN), with the presence of Al3 + and H + Al and without high salinity. The largest Total Organic Carbon (COT) content was in agricultural use of elephant grass (CE) and the consortium (CON) which favored the largest aggregation and aggregate stability in the soil is influenced by soil-landscape relationship. By means of the main components of multivariate analysis demonstrated that some of the chemical characteristics (pH, Ca2+, Mg2+ Sum bases, T, V, CE, Na + and PST were indicators of separation environments). However the most sensitive were (Al 3+, H-Al) / A ausência de diversidade de plantas em sistemas de cultivo agrícolas constitui como uma forma extensiva e preocupante da degradação do solo. Neste contexto, a pesquisa teve como objetivo avaliar os atributos físicos e químicos de um solo em relação a paisagem e usos agrícolas, visando detectar quais desses atributos foram os mais sensíveis na distinção dos ambientes. A pesquisa foi desenvolvida no município de Martins/RN no sítio Bela Vista. Para a caracterização do ambiente em estudo realizou-se a abertura de três perfis representativos e, coletou-se amostras de solos nos horizontes diagnósticos para análises físicas e químicas do solo e posteriormente sua classificação. Foram estudadas seis áreas: consórcio de milho, feijão e mandioca (CON); monocultivo de cana de açúcar (CAN); monocultivo de banana (BN); monocultivo de capim elefante (CE); monocultivo de milho (MM) e mata nativa, como referência (MN). Para o estudo das áreas, coletou-se 6 amostras compostas oriundas de 15 subamostras em cada área supracitadas, com estrutura deformada nas camadas de 0,00-0,10; 0,10-0,20 e 0,20-0,30 m a fim de proceder as análises dos atributos físicos e químicos do solo. As análises foram realizadas nos laboratórios de Física e Fertilidade do Solo da Universidade Federal Rural do Semi-Árido. Quanto a classificação dos solos nos ambientes de cultivo a classificação textural variou dos solos nos ambientes de cultivo a classificação textural variou caracterizando os ambientes nos perfis quanto a classificação textural variou de argilo arenosa, argilosa e muito argilosa, com pH variando de ácido a neutralidade.Verificou-se baixas concentrações de bases trocáveis, consequentemente baixa saturação por bases, considerados distróficos. Quanto aos usos agrícolas seguiu a mesma tendência quanto a fertilidade, sendo que na área de capim elefante apresentou maior qualidade estrutural. Os solos foram classificados em Neossolos Flúvicos nas áreas de cana de açúcar e capim elefante, consórcio, banana e milho e Neossolo Litólico na mata nativa. A classificação textural nos perfis de solo variou de argila arenosa, a argilosa (Neossolos Flúvico), argiloso a muito argiloso (Neossolo Flúvico) e argilo arenoso (Neossolo Litólico). A fertilidade quanto aos usos agrícolas apresentaram reações de acidez para as áreas de Mata Nativa (MN); e Consórcio (CON), tendendo a neutralidade para o Capim Elefante (CE), Milho (MM) e Banana (BAN), com presença de Al3+ e H+Al e sem elevada salinidade. O maior teor de Carbono Orgânico Total (COT) foi nos usos agrícolas de Capim Elefante (CE) e o consórcio (CON) o que favoreceu a maior agregação e estabilidade de agregados no solo, sendo influenciado pela relação solo-paisagem. Por meio dos componentes principais da análise multivariada demostraram-se que alguns dos atributos químicos (pH, Ca2+, Mg2+, Soma de bases, t, V, CE, Na+ e PST foram indicadores da separação dos ambientes). Todavia os mais sensíveis foram (Al3+; H-Al) / 2016-11-01

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-27T14:29:31Z No. of bitstreams: 2 Dissertação - Adan Carlos da Mota - 2015.pdf: 1980205 bytes, checksum: 5a48a15e6c5ae99d024fed60c4d63b9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-04-27T14:31:26Z (GMT) No. of bitstreams: 2 Dissertação - Adan Carlos da Mota - 2015.pdf: 1980205 bytes, checksum: 5a48a15e6c5ae99d024fed60c4d63b9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-04-27T14:31:26Z (GMT). No. of bitstreams: 2 Dissertação - Adan Carlos da Mota - 2015.pdf: 1980205 bytes, checksum: 5a48a15e6c5ae99d024fed60c4d63b9b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-06-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The study of Brazilian agrarian question enables numerous discussions, particularly by the high concentration of land that is in a country with continental dimensions like Brazil. So starting in 2004 with the creation of the National -PNPB- Biodiesel Production and Use Program opens a new range of discussions given that the raw material for biodiesel in several Brazilian regions, such as the Midwest, has been soybeans, thus, areas previously used for the production of pluriculturas are producing monoculture. In southwest Goiás, major grain producing region, the settlements are being invaded by soy. This study aims to draw a historical and analyze the influence of the introduction and development of agricultural production for biodiesel in the settlement Three Bridges in Perolândia (GO), highlighting the environmental and socioeconomic consequences as perceived by the resettled farmers. Using techniques of Participatory Rural Appraisal - DRP-, semi-structured interview, aimed to the direct obtaining primary data, quantitative aspects, translating into numbers the opinions and information analyzed; and qualitative translated for what can not be measured by observing the reality and the subject as inseparable elements. The survey results point to a mischaracterization that location actor because there was abandonment of multi-culturality at the expense of soybean planting, small producers who joined the PNPB left to produce food. On the grounds that the objective PNPB social inclusion and regional development by generating employment and income, the federal government encouraged the creation of links between agribusiness companies that benefit from the tax incentives own government and farmers, descaracterizando and transforming this segment, which is essential, not only for security but also for national food sovereignty. / O estudo da questão agrária brasileira possibilita inúmeras discussões, principalmente pela alta concentração de terras que há em um país com dimensões continentais como o Brasil. Assim, a partir de 2004, com a criação do Programa Nacional de Produção e Uso do Biodiesel -PNPB- abre-se um novo leque de discussões, tendo em vista que a matéria prima para o biodiesel em diversas regiões brasileiras, como o Centro-Oeste, tem sido a soja, com isso, áreas antes destinadas à produção de pluriculturas estão produzindo monocultura. No Sudoeste Goiano, importante região produtora de grãos, os assentamentos estão sendo invadidos pela soja. O presente estudo objetiva traçar um histórico e analisar as influências da introdução e evolução da produção agrícola destinada ao biodiesel, no assentamento Três Pontes, em Perolândia (GO), destacando os reflexos ambientais e socioeconômicos segundo a percepção dos agricultores assentados. Com a utilização de técnicas do Diagnóstico Rural Participativo - DRP-, entrevista semiestruturada, visou-se à obtenção direta de informação primária, aspectos quantitativos, traduzindo em números as opiniões e informações analisadas; e qualitativos traduzidos por aquilo que não pode ser mensurável, observando a realidade e o sujeito como elementos indissociáveis. Os resultados da pesquisa apontam para uma descaracterização desse ator local, pois houve abandono da pluricultura em detrimento do plantio de soja, os pequenos produtores que aderiram ao PNPB deixaram de produzir alimentos. Sob o argumento de que o PNPB objetiva a inclusão social e o desenvolvimento regional via geração de emprego e renda, o Governo Federal incentivou a criação de laços entre empresas do agronegócio, que se beneficiam com incentivos fiscais do próprio Governo e os agricultores familiares, descaracterizando e transformando esse segmento, que é essencial, não só para a segurança, mas também para a soberania alimentar nacional.

Modificações da cobertura natural dos solos podem ocasionar alterações no ciclo hidrológico, que por sua vez podem impactar a disponibilidade de água. Na Bacia Hidrográfica do Rio Paraíba do Sul (BHPS) vem ocorrendo uma substituição de coberturas vegetais em função da expansão de monoculturas de eucalipto. O objetivo desta pesquisa foi verificar os impactos de ordem hidrológica sobre a disponibilidade hídrica (quali e quantitativa) no trecho paulista da BHPS, em decorrência da implantação da atividade de silvicultura de eucalipto para produção de celulose. Para isso, foi utilizado o método de Pegada Hídrica (PH) para avaliar a alocação de água da produção de madeira de floresta nativa e de eucalipto, método que vem sendo aplicado pelo setor silvícola. Foram empregados também métodos de Balanço Hídrico Climatológico, Balanço Hídrico Geral e a abordagem de Serviços Ecossistêmicos para avaliar a relação entre a água e as principais coberturas vegetais da bacia (pastagem, floresta nativa e eucalipto), de forma a permitir uma análise ampliada e integrada do comportamento hidrológico da bacia. Ao analisar os métodos empregados, observou-se que a PH de produtos avalia apenas a eficiência do uso da água, o que pode mascarar altos consumos de água em função de maior produtividade por hectare. Isto porque se obteve menor valor de PH da madeira, em m³ por tonelada para o caso do eucalipto, e maior alocação total de água, em m³ por hectare por ano, em comparação à floresta nativa. Os resultados obtidos pela análise de Balanço Hídrico Climatológico para as principais coberturas vegetais mostraram que o eucalipto apresentou maior evapotranspiração e menor excedente hídrico. Já o Balanço Hídrico Geral, analisado mensalmente, permitiu visualizar que as coberturas vegetais influenciam o serviço de provisão de água e concorrem pelo uso de água com os demais usuários da bacia (naturais e antrópicos) em períodos de menor precipitação. Por fim, concluiu-se que são necessárias medições locais para determinação de volumes de escoamento (superficial e subterrâneo), infiltração, bem como do processo de lixiviação e perdas de solo para apontar de forma mais precisa os impactos hídricos da monocultura de eucalipto. / Modifications in the natural land cover can change the hydrological cycle, which might have an impact on water availability. In the river basin of the Paraíba do Sul river (RBPS), the natural vegetation has been being replaced due to the expansion of eucalyptus monocultures. This research assessed the impacts on water availability (both qualitative and quantitative), caused by eucalyptus forestry for pulp production in the RBPS part in Sao Paulo. The water footprint (WF) method was applied to assess the water used on the cellulose production of native forest and eucalyptus, given the use of this method by the industry. Also, the Climatic Water Balance, General Water Balance methods and the Ecosystem Services approach were used in order to perform an extended and integrated analysis of the hydrological behavior of the basin. By analyzing these methods, it was found that the products WF only assesses the efficiency in water use, which can mask high water consumption with higher productivity per hectare. This because a smaller value for wood WF was observed, in m³/ton for eucalyptus, and higher total water use, in m³ per hectare per year, compared to the native forest. The results observed by the Climatic Water Balance analysis for the main vegetation cover showed that the eucalyptus presented higher evapotranspiration and smaller water surplus. The General Water Balance, analyzed on a monthly basis, showed that the vegetation has an impact on the water provision service and competes for water with other users in the basin (natural and anthropic) in periods with less precipitation. Finally, it was concluded that local measurements are required to determine the runnof volumes (superficial and subsurface), infiltration, as well as the process of leaching and soil loss in order to have a more accurate assessment of the hydrological impacts of the eucalyptus monoculture.

Despite the importance of a high white clover (Trifolium repens) content in temperate pastoral systems in terms of livestock performance and nitrogen fixation, the proportion of white clover in grass-clover pastures is often low (<20%). This thesis examined in two experiments whether the white clover content of pastures could be improved by sowing white clover with alternative grass species to diploid perennial ryegrass (Lolium perenne L.). In a pasture experiment, DM production, pasture composition and morphology of grass-clover mixtures was measured over the establishment year (January 2007 to January 2008) where white clover was sown in fine mixtures with diploid perennial ryegrass, tetraploid perennial ryegrass, timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.). Pastures were irrigated and rotationally grazed with on-off grazing with Coopworth ewe hoggets. Total annual DM production of pasture was more than 20% higher in tetraploid (12521 kg DM ha⁻¹) and diploid (11733 kg DM ha⁻¹) perennial ryegrass than timothy (9751 kg DM ha⁻¹) and cocksfoot (9654 kg DM ha⁻¹). However, timothy (5936 kg DM ha⁻¹) and cocksfoot (5311 kg DM ha⁻¹) had more than four times higher white clover annual DM production than tetraploid (1310 kg DM ha⁻¹) and diploid (818 kg DM ha⁻¹) ryegrass. Pasture growth rate at the first three harvests in autumn was significantly greater in tetraploid and diploid ryegrass than timothy and cocksfoot. Timothy and cocksfoot had a higher proportion of white clover than tetraploid and diploid perennial ryegrass throughout the entire year. This was due to more and larger white clover plants in timothy and cocksfoot plots. In a grazing preference experiment, the partial preference of sheep for white clover offered in combination with the same grass species as in the pasture experiment was measured in five grazing tests in May, September, October, November and December 2007. Pastures were sown in January 2007. Paired plots (grass and clover both 4.2 m x 10 m) were grazed by three Coopworth ewe hoggets between 9am and 5pm, and preference was recorded by decline in pasture mass and visual scan sampling for grazing time. Grazing preference for clover was generally low throughout these tests (e.g. average apparent DM intake from clover = 47%; average grazing time from clover = 44%). Several explanations are proposed for this low preference including a high N content and intake rate of the grass relative to the clover. No significant differences were found among the grass treatments in total grass grazing time, total clover grazing time, ruminating time, the proportion of grazing time on clover, selective coefficient for clover and DM intake percentage from clover at any date. There was no significant change in overall sward surface height (SSH) decline among grass treatments throughout all the tests except December 2007 when the overall SSH decline for cocksfoot was significantly lower than the other species. The study indicated that the rapid growth rate of perennial ryegrass in the early phase of pasture establishment, rather than differences in partial preference, was the key factor limiting white clover content in the mixed swards relative to cocksfoot and timothy pastures. It is concluded that high clover-containing pastures capable of delivering high per head performance can be established through the use of slow establishing pasture species such as timothy and cocksfoot.

Les fourmis sont des organismes cibles appropriés pour les études environnementales. Au cours de notre étude, nous nous sommes focalisés sur les fourmis de la litière via l'application de deux méthodes de récolte complémentaires selon le protocole all (ants of leaf litter). Dans les forêts naturelles de Guyane française, l'hétérogénéité environnementale et les perturbations structurent les communautés de fourmis de la litière en influençant la richesse, la diversité, l'abondance et la densité en espèces ainsi que les compositions taxonomique et fonctionnelle. Chaque type de formation végétale possède une communauté spécifique. La fragmentation et la conversion des forêts en plantations ont entrainé une altération plus ou moins profonde des communautés; cette variabilité est fonction du type d’agriculture et des espèces d'essences cultivées. Bien que l'altération des communautés se soit révélée maximale dans la plupart des monocultures, les plantations de cacaoyers ont un potentiel de conservation réel. Enfin, dans un contexte ou il est urgent de simplifier l'intégration des arthropodes dans les études de conservation, de contrôle et de suivi de la santé des écosystèmes terrestres, la méthode des réseaux de neurones est apparue comme un outil puissant pour mettre en évidence et analyser les patrons des communautés de fourmis. / Ants are reliable and relevant target organisms for environmental surveys. In our study, we focused on litter-dwelling ants through the use of two complementary sampling methods that were implemented according to the ants of leaf litter (all) protocol. In pristine forests of french guiana, leaf-litter ant communities are structured by environmental heterogeneity and natural perturbations - which influence species richness, diversity, abundance and density, as well as taxonomic and functional composition. This results in habitat-specific communities for each vegetal formation. Forest fragmentation and conversion into monocultures have led to a more or less deep alteration of the ant communities; this variability depends on the type of agricultural system and cultivated tree species. Although the intensity of community alteration peaked in tree monocultures, cocoa plantation exhibited a real potential for native species conservation. Finally, in the current context where simplifying the integration of arthropods into conservation programs as well as into surveys designed to monitor and manage the environment is critical, the use of neural networks appears to be a powerful tool for reliably highlighting and analyzing ant communities patterns.