Made available in DSpace on 2017-07-10T17:30:17Z (GMT). No. of bitstreams: 1 Ana_Paula_Stasiak.pdf: 6576934 bytes, checksum: 2a7f5dfaa2eccfd9cce5a56afda8f804 (MD5) Previous issue date: 2013-07-08 / The agro-ecological farming has got started by social movements in favor to the rural sustainable development based on environmental, social and economic. Agroecologyis presented as an alternative to modernization of agriculture that repair environmental damage and social damage caused by the green revolution technology disseminated and adopted by the Brazilian government as a development policy based on the economic growth. This paper aims to analyze the agro-ecology alternatively forward the modernization process of the agriculture and the different territorialities provided by the two forms of production, as well as identify the limits and difficulties of territorial agro-ecological practices in Coronel Vivida, held bibliographic review the topic addressed and fieldwork, using a questionnaire addressed to eleven farmers who have comprised three distinct groups related to agro-ecology in the town: Farmers Convention with SAFs; 2) Agro-ecological Farmers; 3) Farmers Convention-Former Agro-ecological Farmers. And interviews with representatives of institutions related to agriculture and agroecology family whose work is in the town. The study of these three groups with different production and commercial organizations had allowed us to observe the process of territorialization and deterritorialization of simultaneous agro-ecological practices, the latter prevails. Another methodology used to characterize the properties sustainable, based on agro-ecological principles, as well as differentiate the analysis was made landscapes through sketches and photographs of the properties studied. This paper outlines the main difficulties faced by the town farmers relationed to agro-ecological production, as well as the main factors which have influenced the abandonment of agro-ecological practices by the Coronel Vivida agro-ecological farmers. / A agricultura agroecológica surge de movimentos sociais em favor de um desenvolvimento rural sustentável, baseado nas condições ambientais, sociais e econômicas. A Agroecologia é apresentada como alternativa a modernização da agricultura visando reparar os danos ambientais e prejuízos sociais causados pela tecnologia disseminada pela revolução verde e adotada pelo Estado brasileiro como política desenvolvimentista baseada no crescimento econômico. Com o objetivo de analisar a Agroecologia como alternativa frente ao processo de modernização da agricultura e as diferentes territorialidades proporcionadas pelas duas formas de produção, assim como, identificar os limites e dificuldades de territorialização das práticas agroecológicas em Coronel Vivida, realizou-se revisão bibliográfica sobre o tema abordado e trabalho de campo, com aplicação de questionário dirigido à onze agricultores familiares que compõem três grupos distintos relacionados com a Agroecologia no município: 1) Agricultores Convencionais com SAFs; 2)Agricultores Agroecológicos; 3)Agricultores Convencionais Ex-Agricultores Agroecológicos. E entrevistas com representantes de instituições ligadas a agricultura familiar e a Agroecologia que atuam no município. O estudo desses três grupos que apresentaram organizações produtivas e comerciais diferentes nos permitiu constatar o processo de territorialização e desterritorialização simultâneas das práticas agroecológicas, prevalecendo esse último. Outra metodologia utilizada para caracterizar os estabelecimentos sustentáveis, baseados nos princípios agroecológicos, assim como, diferenciar as paisagens constituídas foi à análise através de croquis e fotografias dos estabelecimentos em estudo. O presente texto aponta as principais dificuldades enfrentadas pelos agricultores do município em relação à produção agroecológica, assim como, os principais fatores que influenciaram no abandono de práticas agroecológicas por parte dos ex-agricultores agroecológicos de Coronel Vivida.

Cette thèse de doctorat en géographie sociale et politique analyse les jeux d’acteurs dans la gouvernance foncière au Cameroun à l’aune des affectations foncières à des fins agro-industrielles qui y prévalent et qui ont pris des proportions ces dernières années suite à la politique économique axée sur l’attractivité des investissements directs étrangers adoptée par les autorités camerounaises dans la perspective du développement. Cette situation a fondamentalement induit une intensification des investissements dans le domaine de l’exploitation des ressources naturelles et spécifiquement de la ressource foncière. Ce qui n’a pas manqué d’attirer l’attention des médias et Ong tant locaux qu’internationaux qui accusent d’accaparement des terres les firmes agricoles étrangères qui y sont actives. Eu égard à ces griefs, le but de cette étude est d’apporter des éléments de clarification sur la situation qui y prévaut vraiment. Car, même si les compagnies agricoles étrangères ayant acquis ou sollicitant des terres au Cameroun ne sont pas vertueuses ; se focaliser sur elles comme étant les princes de la turpitude alors que les acteurs étatiques locaux en charge des politiques publiques en matières foncière seraient, par nature, des parangons de vertu n’est pas la bonne approche. Cette étude trouve son fondement dans le fait que plusieurs catégories d’acteurs aux intérêts divers et variés structurent l’écosystème des transactions foncières agro-industrielles au Cameroun. / This doctoral dissertation in social and political geography analyzes the actors' play in land governance in Cameroon in the light of the land uses for agro-industrial purposes that prevail and which have taken proportions in recent years following the policy economic policy focusing on the attractiveness of foreign direct investment adopted by the Cameroonian authorities in the perspective of development. This situation has fundamentally led to an intensification of investments in the field of exploitation of natural resources and specifically land resources. This has not failed to attract the attention of both local and international media and NGOs who accuse foreign agribusinesses active in the country of land grabbing. In view of these grievances, the purpose of this study is to provide clarification on the situation that really prevails. For, even if foreign agricultural companies having acquired or soliciting lands in Cameroon are not virtuous; to focus on them as princes of turpitude, while local state actors in charge of public land policies would be, by nature, paragons of virtue is not the right approach. This study is based on the fact that several categories of actors with diverse and varied interests structure the agro-industrial land transactions ecosystem in Cameroon.

Fornendo energia e nutrienti, la produzione di cibo è essenziale per la vita. Tuttavia, essa rappresenta anche una criticità ambientale. La popolazione mondiale in rapida crescita, infatti, ha bisogno di un quantitativo di cibo sempre maggiore, una delle principali cause di degrado ambientale a livello globale. Il sistema agricolo è fondato su una rete di relazioni complesse che collegano la produzione agricola, funzioni e condizioni ambientali. Una produzione agricola meno impattante è, quindi, fondamentale per non compromettere la possibilità per la future generazioni di avere accesso a un quantitativo adeguato di risorse. La metodologia LCA (life cycle assessment) ha un ruolo centrale nella valutazione di sostenibilità. Analizzando l’intero ciclo di vita di un prodotto o servizio, infatti, permette di tenere in considerazione eventuali trasferimenti di impatti tra comparti ambientali o fai della filiera. Il principale obiettivo della presente tesi è contribuire al dibattito in corso riguardo all’armonizzazione degli approcci nell’applicazione della metodologia LCA a prodotti agro-alimentari per favorirne l’affidabilità e l’efficacia. / Providing energy and nutrients, food production is essential for life. However it represents also an important environmental concern. Indeed, the rapidly growing world population is requiring an increased food production which is one of the greatest causes of environmental degradation throughout the world. The agricultural system is based on complex relations that link agricultural productivity, environmental functions and environmental conditions. Therefore, moving towards less polluting production systems is of the utmost importance to satisfy the current demand for food without compromising the possibility for future generations to have access to a proper amount of food of adequate quality. Life cycle assessment (LCA) methodology is at the core of sustainability assessment. Indeed, considering the entire life cycle of a product or service, it allows to account for potential shifts of environmental impacts between environmental compartments or stages of the food supply chain. The overall aim of the present thesis is to contribute to the ongoing debate on the harmonisation of the approaches to carry out a LCA referred to agro-food products in order to foster its reliability and effectiveness.

Made available in DSpace on 2016-06-02T19:39:41Z (GMT). No. of bitstreams: 1 5834.pdf: 1141487 bytes, checksum: 22677092e6667a2beb26226f31fd2bdd (MD5) Previous issue date: 2014-02-28 / Financiadora de Estudos e Projetos / The agrarian reform settlements have been configured as a territory in costant dispute for capital, through agro-industrial partnerships, and are legalized by Ordinance state 77/2004, which allows the cultivation of the crops for agro-industrial ends at the state settlements of São Paulo, pointing them in a new direction. From this reality this essay has a goal to analyze the relation between Work and Education on these settlements, aiming to understand in which way the settled worker acquires the knowledge necessary for the production and how this agro-industrial knowledge interferes on the work developed. The field research was performed in the Guarani Settlement situated in the city of Pradópolis in the state of São Paulo, which has an agro-industrial partnership with a nearby plant, named Usina São Martinho. It was found that the work formation occurs mostly through experience and exchange of knowledge. This knowledge comes from previous generations, which were moved from the field and denied access to the land due to the technologic development which mechanized the field production. Few families have frequented schools. The search for knowledge about planting and crops also can be seen in the exchange of experiences with neighbors and even from practice itself. The technical advice from Institution ITESP and INCRA, due to the large number of families, has not been available for everyone. We concluded that the agro-industrial partnerships appear in the settlements after a process of exhausting the land of any other possibilities and are characterized as contradictory alternatives to the process of land struggle, although are accepted due to the precarious socioeconomic conditions of the people. / Os assentamentos de reforma agrária têm se configurado como um território em disputa pelo capital por meio das parcerias agroindustriais, legalizadas pela Portaria Estadual 77/2004, que permitem o cultivo de lavouras para fins agroindustriais nos assentamentos estaduais do Estado de São Paulo, dando um novo direcionamento para os assentamentos. A partir desta realidade, este trabalho tem como objetivo analisar a relação entre Trabalho e Educação no assentamento, com a finalidade de compreender de que forma o trabalhador assentado se apropria de conhecimentos para a produção e como o conhecimento pautado na agroindústria interfere no trabalho que ele desenvolve. A pesquisa de campo foi realizada no Assentamento Guarani situado na cidade de Pradópolis SP-, que tem uma parceria agroindustrial com a Usina São Martinho. Constatou-se que a formação para o trabalho ocorre praticamente na vivência e troca de experiências. Os conhecimentos vêm das gerações anteriores, que foram desapropriadas do campo e acesso a terra devido ao desenvolvimento tecnológico que mecanizou a produção no campo. Poucas famílias possuem formação escolarizada. A busca de conhecimentos sobre a plantação das culturas se dá também na troca de experiências com vizinhos e até mesmo na própria prática. A assessoria técnica da Fundação ITESP e do INCRA, devido ao grande número de famílias, nem sempre tem sido acessível para todos. Concluímos que as parcerias agroindustriais surgem nos assentamentos após um processo de esgotamento de todas as possibilidades para o desenvolvimento do lote e que se caracterizam como alternativas contraditórias do processo de luta pela terra, mas, são aceitas devido as precárias condições socioeconômicas dos sujeitos.

Na medida em que as demandas agrícolas continuam se expandido, aumenta a necessidade de que a produção agrícola garanta a conservação da diversidade e a provisão de serviços ecossistêmicos. O intuito do trabalho é avaliar independentemente o efeito da distancia aos fragmentos florestais e a cobertura florestal numa escala local. Quantificamos a diversidade de abelhas e a formação de frutos em 24 cultivos de café dentro de paisagens complexas de 2km de radio, compostas por mosaico de usos da terra, café, Mata Atlântica (20 - 27%) e outros usos. Adicionalmente estimamos a contribuição das espécies na formação de frutos depois de uma visita única, em cinco dos 24 pontos amostrais. No total foram identificadas 31 abelhas que visitam o café, a maioria abelhas sem ferrão (Meliponini) e abelhas da família Halictidae. No existiu diferencia na formação de frutos depois das visitas únicas das diversas especies de abelhas, o que sugere que há uma complementaridade na provisão do serviço. No entanto, a maior produtividade esteve associada à abundância de abelhas nativas. Em geral, 8% foi o incremento associado ao papel das abelhas o qual diminuiu com aumento da distancia para os fragmentos de mata assim como também conforme aumentava a quantidade de café na escala local (400 m de raio no entorno do ponto amostral). O efeito negativo da distancia aos fragmentos reforça a importância da vegetação natural em prover diversidade de abelhas e por tanto o serviço de polinização. O efeito negativo da cobertura de café sobre a frutificação sugere que há um excesso de demanda que excede a capacidade dos polinizadores de prover o serviço dentro de paisagens complexas. Nossos resultados mostram que a estrutura da paisagem afeta a densidade, riqueza e composição de espécies de polinizadores. Por tanto recomendamos como estratégia para incrementar a produção de café, sem necessidade de aumentar a cobertura florestal, manegar as áreas agrícolas para aumentar a dispersão entre fragmentos florestais e plantios de café, com o intuito de criar paisagens mais fragmentadas que facilitem o fluxo de polinizadores ao café / As the demands on agricultural lands continue to expand, effective strategies are urgently needed to manage agricultural production to guarantee biodiversity conservation and ecosystem service provision. Here we assessed independently the effect of forest isolation and local forest cover over bee diversity and on the provision of pollination service to coffee. We quantified bee diversity of flower visitors and fruit set in 24 coffee fields within three complex landscape of 2km radius surrounded by mosaic of coffee plantations, Atlantic forest fragments (20 - 27%), pastures and other lands uses. Additionally, we estimated species contribution to fruit set after single visit in five of the 24 coffee sites. In total we identified 31 bee species visiting coffee flowers, most being stingless bees (Meliponini tribe) and sweat bees (Halictidae). The absence of difference in fruit set after single visit by Apis and natives bee suggest that service complementation. Although, higher abundances of sweat bees and stingless bees were positively related to fruit set. Coffee fruit set was overall 8% higher in the presence of bees, and responded negatively to isolation from forest fragments and to high coffee cover at a local landscape scale (400 m radius landscape surrounding each sampled coffee bush). The negative association between isolation and fruit set reinforces the importance of natural vegetation to enhance bee diversity and therefore the provision of pollination service. The negative effect of coffee cover on fruit set suggests that the service demand can surpass pollinators\' capacity to provide service within complex landscape. Our results provide clear evidences that landscape structure can affect the abundance, richness and composition of pollinators\' species, and thus can indirectly regulate the provision of pollination service. Therefore we recommend, as a strategy to increase coffee yields without necessarily expanding forest cover, to manage agricultural landscapes in order to increase interspersion between forest fragments and coffee plantation thus a more patchy landscape mosaic that may facilitate pollinators flows to coffee crop

L'agriculture fait face à une crise environnementale qui rend nécessaire la prise en compte du fonctionnement des « écosystèmes ». Mais ce concept de l'écologie donne peu de prise à l'action dans le secteur agricole. Les champs de littérature sur les « biens communs » et sur les « services écosystémiques », qui traitent de la gestion des écosystèmes, ont été abondamment développés et relayés par les politiques publiques. La thèse montre qu'ils cristallisent souvent les conflits entre les objectifs agricoles et les préoccupations écologiques sans pour autant permettre l'exploration de nouveaux systèmes agricoles.Notre thèse en sciences de gestion met en évidence qu'un nouvel enjeu pour la recherche scientifique est d'apprendre à piloter les régulations écologiques au sein des agro-écosystèmes de manière à rendre l'agriculture durable. Elle cherche à définir les modalités d'une démarche de conception des agro-écosystèmes : peuvent-ils faire l'objet de démarches de conception innovantes ? Quelles sont les méthodes pour les concevoir ? Et quels sont les modes de gouvernance appropriés ?L'analyse historique des raisonnements scientifiques en agronomie et en écologie met en évidence les raisons qui rendent difficiles aujourd'hui la conception des agro-écosystèmes, malgré les connaissances de plus en plus fines sur les régulations écologiques. La thèse modélise une classe d'objets particuliers, les « fonds écologiques », que les scientifiques introduisent pour aborder les agro-écosystèmes en s'affranchissant des seuls schémas connus. Elle montre l'intérêt de ne pas considérer les fonds écologiques comme des biens communs mais comme des « inconnus communs ». Le modèle proposé, testé sur un archétype de la production intensive en région céréalière, permet d'élaborer une méthode de conception collective et innovante des agro-écosystèmes. / Agriculture is facing an environmental crisis that makes it necessary to take into account the “ecosystem” functioning. But this concept of ecology is difficult to handle in the agricultural sector. Fields of literature on the "commons" and the "ecosystem services", which deal with the management of ecosystems, have been extensively developed and relayed by public policy. The thesis shows that they often freeze the conflict between agricultural objectives and environmental concerns without allowing the exploration of new farming systems.Our thesis in management science highlights the fact that a new challenge for scientific research is to learn to manage environmental regulations within agro-ecosystems in order to make agriculture sustainable. It aims to define a design approach of agro-ecosystems: can innovative design be applied to them? What are the methods to design agro-ecosystems? And what are the appropriate modes of governance?The historical analysis of scientific reasoning in agronomy and ecology highlights the reasons why the design of agro-ecosystems remains so difficult, despite finer knowledge on environmental regulations. The thesis models a particular class of objects, the “ecological fund” that scientists introduced to deal with agro-ecosystems while escaping the already known patterns. It shows the importance of considering the ecological funds not as common goods but as "common unknowns”. The proposed model, tested on an archetype of an intensive cereal production area, makes it possible to develop a method of collective and innovative design of agro-ecosystems.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Agro-IBIS model is validated for a soybean experimental site in the state of Rio Grande do Sul. This experiment is conducted in order to evaluate the impact of different soil management systems on different areas of science. In the site, we obtained micrometeorological measures of energy, mass and water exchanges between the soybean ecosystem and the environment during the 2009/2010 soybean growing season. We used two management systems: (1) no-tillage system (NT) and (2) conventional tillage system (CT). The model was forced with meteorological data from the Brazilian National Institute of Meteorology (INMET). The results of the model were compared with the observed data in order to evaluate the capacity of the model in simulating the interaction of the soybean ecosystem with environment and also to verify the effects of surface coverage by crop residues in NT. Since the model does not have the representation of crop residues, i.e., of NT, its effects are not expected in the simulation results. The results indicate that the model simulates the radiative balance and flows of energy in a satisfactory way. Besides this, soil moisture in the 0-20 cm and 20-50 cm layers and the 0-50 cm integration as well as soil temperature at 2 cm are simulated in a suitable way. For soil moisture, the simulated results represent better the observed data in CT, indicating that the effect of soil coverage by crop residues is not simulated. In the variables related to CO2, the model has problems concerning the simulation of the ecosystem respiration, which is strongly underestimated. This leads to an inconsistency in the simulation of the others variable related to CO2, mainly of those which consider the night-time data, since at night the net CO2 exchange of the ecosystem (NEE) is the respiration. For the daytime CO2 the model shows good performance, except in the period of leaf senescence, when the model indicates CO2 uptake by the ecosystem and the experimental data indicate emission. / O modelo Agro-IBIS é validado para um sítio experimental com o cultivo de soja no estado do Rio Grande do Sul. No sítio é conduzido um experimento que tem como objetivo avaliar o impacto dos diferentes sistemas de manejo do solo em diversas áreas do conhecimeto. No sítio foram coletadas medidas micrometeorológicas das transferências de energia, massa e água entre o ecossistema da soja e a atmosfera durante o ciclo 2009/2010 da soja. O monitoramento se deu sobre dois sistemas de manejo: (i) o sistema de plantio direto (SD); (ii) sistema de plantio convencional (SC). As simulações com modelo Agro-IBIS para a soja foram realizadas com o modelo sendo forçado com dados meteorológicos do Instituto Nacional de Meteorologia (INMET). Os resultados do modelo foram comparados com os dados observados nos SD e SC a fim de avaliar a capacidade do modelo em simular a interação do ecossistema da soja com o ambiente e, também, com o intuito de verificar os efeitos da cobertura da superfície pelos resíduos culturais no SD. Como o modelo não possui a representação dos resíduos culturais, ou seja, do SD, é esperado que seus efeitos não sejam perceptíveis nos resultados simulados. Os resultados indicam que o modelo simula o balanço radiativo e os fluxos de energia de forma consistente. Além disso, a umidade do solo nas camadas 0-20cm, 20-50cm e a integração 0-50 cm, assim como a temperatura do solo a 2cm são simuladas de forma robusta. Na umidade do solo, os resultados simulados melhor representam os dos dados observados no SC, indicando que o efeito da cobertura do solo pelos resíduos culturais não é considerado. Nas variáveis relacionadas ao CO2, é possível verificar que o modelo tem problemas em relação à simulação da respiração do ecossistema, que é fortemente subestimada. Isso leva a uma inconsistência na simulação das demais variáveis relacionadas ao CO2, principalmente àquelas que consideram os dados noturnos, já que à noite a troca líquida de CO2 (NEE) do ecossistema é a respiração do mesmo. Quando a análise dos resultados relacionados ao CO2 é restrita aos dados diurnos o modelo tem bom desempenho, exceto no período de senescência foliar, quando o modelo segue indicando absorção de CO2 pelo ecossistema e os dados experimentais indicam emissão.

L’agro-composite de chanvre/amidon est un nouveau matériau 100% végétal constitué d'amidon et de chènevotte. C’est un matériau durable pour la construction et le bâtiment. L'objectif principal de cette thèse est d’innover, développer et optimiser cet agro-composite ainsi que ses propriétés mécaniques, acoustiques et thermiques. Dans ce travail, des essais expérimentaux sur le comportement mécanique, acoustique et thermique sont réalisées. Un liant particulier et innovant a été préliminairement testé et analysé afin de déterminer une composition optimale. Deux paramètres prépondérants de cette étude sont : le rapport chanvre/amidon (C/A) et la taille des particules de chènevotte. Différents mélanges de particules de chènevotte 0-20 mm, 0-15 mm et 0-5 mm sont donc étudiés en faisant varier le rapport de chènevotte/amidon (C/A) de 6, 8, 10, 12 à 14. La comparaison et l’analyse des résultats permet de mettre en lumière l’influence de chacun des paramètres sur les caractéristiques de notre agro-composite chanvre/amidon. Les agro-composites chanvre/amidon avec des mélanges de particules de chènevotte 0-5/0-15 mm et 0-5/0-20 mm, montrent qu’il existe une formulation qui permet d’obtenir un comportement mécanique optimal, un meilleur comportement acoustique et un excellent comportement thermique. / The hemp/starch agro-composite is a new material consisting of 100% vegetal starch and hemp shives. It is a durable material for building and construction. The aim of this thesis is to innovate, develop and optimize the agro-composites and those properties mechanical, acoustic and thermal behavior. In this work, experimental tests on the mechanical, thermal and acoustic behavior have been carried out. A particular and innovative binder has been preliminarily tested and analyzed in order to determine optimum composition. Both parameters studied are: hemp/starch (C/A) ratio and size of hemp shives. Various mixtures of hemp shives 0-20 mm or 0-15 mm with 0-5 mm were studied by varying the hemp/starch (C/A) ratio from 6, 8, 10, 12 to 14. The comparison and analysis of results allows making the obvious influence of each parameter on the characteristics of our hemp/starch agro-composite. The hemp/starch agro-composite with mixtures hemp shives 0-5/0-15 mm and 0-5/0-20 mm, show that there is a formulation that achieves optimum mechanical behavior, better acoustic behavior and excellent thermal behavior.

En réponse aux pertes de biodiversité et à une insécurité alimentaire croissante, l’agriculture moderne doit se tourner vers une gestion plus durable des paysages agricoles. L’Agriculture Biologique (AB) est considérée comme une solution prometteuse à ces enjeux. En effet, ses pratiques agricoles étant globalement plus favorables aux ennemis naturels de ravageurs que celles de l’Agriculture Conventionnelle (AC), elle pourrait permettre de remplacer l'utilisation des pesticides par celle du contrôle biologique. Cependant, les études évaluant ces effets restent contradictoires, probablement car elles ne tiennent pas compte de la diversité des pratiques réalisées en AB et en AC. A plus large échelle, les pratiques ont par ailleurs rarement été considérées dans la description de l’hétérogénéité paysagère, bien que la nature et l’organisation spatiale de la matrice agricole soit susceptible d’affecter les espèces qui y vivent. L’objectif de ce travail de thèse est d’évaluer les effets de la diversité et de l’organisation spatiale des pratiques en AB et en AC sur les insectes auxiliaires, à l’échelle de la parcelle et du paysage. Un travail de terrain a été réalisé en 2012 et 2013 en Ille et Vilaine. Quarante paires de parcelles de blé d’hiver en AB et en AC ont été sélectionnées, réparties le long d’un gradient paysager de surfaces en AB. Dans chaque parcelle, les communautés d'ennemis naturels de pucerons (coccinelles, carabes, parasitoïdes) ont été échantillonnées. Des enquêtes ont permis de caractériser les pratiques agricoles réalisées par les agriculteurs dans les parcelles suivies et dans leur environnement paysager. Nous avons mis en évidence l’existence d’une large diversité de pratiques agricoles dans les systèmes en AB et en AC. A l’échelle parcellaire, les effets des pratiques sur la diversité des insectes auxiliaires sont forts, les systèmes en AB leur étant globalement plus favorables. Considérer un niveau plus fin de description des pratiques nous a permis d’identifier celles qui affectent réellement les insectes et de montrer qu’il est possible de favoriser leur présence, quel que soit le mode de production. A l’échelle du paysage, nous n’avons mis en évidence aucun effet de l’étendue et de l’organisation de l’AB sur les ennemis naturels. Une description plus fine des pratiques nous a malgré tout permis de souligner l’importance de certaines stratégies de pratiques, à certaines échelles. A partir de ces résultats, nous proposons des pistes pour l’aménagement des paysages agricoles. Les problèmes méthodologiques liés à la description des pratiques agricoles à l’échelle du paysage sont également discutés. / Due to the loss of biodiversity and increasing food insecurity, modern agriculture must evolve toward a more sustainable management of agricultural landscapes. Organic Farming (OF) is considered as a promising solution to meet this challenge. Organic practices are indeed generally more favorable to pest natural enemies than Conventional Farming (CF), suggesting that pesticides could be replaced by biological control. However, studies evaluating these effects are contradictory, probably because they do not consider the diversity of practices implemented in OF and CF. On a broader scale, practices have rarely been considered in the description of landscape heterogeneity, although the nature and configuration of farmland must affect species. The target of this PhD work is to evaluate the effects of the diversity and spatial organization of organic and conventional farming practices on insect natural enemies, at field and landscape scales. A fieldwork was conducted in 2012 and 2013 in Brittany. Forty pairs of organic and conventional winter wheat fields were selected, distributed along a landscape gradient of OF area. In each field, aphid natural enemies (ladybirds, carabid beetles, parasitoids) were sampled. We interviewed farmers to characterize farming practices implemented in fields and their surrounding landscape. We observed a wide diversity of farming practices in OF and CF. At field scale, effects of practices on the diversity of natural enemies were strong, OF being overall more favorable. Considering a finer description of practices allowed us identifying those really affecting insects, and showing they can be enhanced regardless of the farming type. At landscape scale, we found no effect of the OF area and configuration on natural enemies. With a more detailed description of practices, we however highlighted the importance of some farming strategies, at some scales. Based on these results, we open up avenues to manage agricultural landscapes. Methodological issues related to the description of farming practices on large areas are also discussed.

El objetivo de la presente investigación es analizar cada una de las 4 dimensiones del modelo Uppsala, “reconocimiento de oportunidades”, “posición de la red de contactos”, “aprendizaje, creación y construcción de la confianza” y “decisiones de relación de compromiso”, las cuales son empleadas por las agro exportadoras hacia Estados Unidos de palta Hass en Ica. Hallando así, diferentes variables dentro de estas dimensiones que se emplean para lograr la internacionalización del agro exportador iqueño. El enfoque de la investigación es mixto, se comenzó con un análisis cualitativo donde se usó como herramienta la entrevista a profundidad, realizada a 6 expertos para poder validar las variables más destacadas dentro las 4 dimensiones establecidas en Uppsala. Luego se realizó el análisis cuantitativo, en donde la herramienta que se empleó fue una encuesta aplicada a las 10 empresas agro exportadoras de palta Hass iqueñas pertenecientes a la población total de la investigación. Analizamos los resultados aplicando el modelo de análisis factorial, el cual nos ayudó a hallar perfiles de las agro exportadoras por cada dimensión. Los resultados obtenidos concluyen que las dimensiones “reconocimiento de oportunidades” y “aprendizaje, creación y construcción de la confianza” del modelo Uppsala son las más influyentes en la internacionalización de la palta Hass de agro exportadoras iqueñas. Asimismo, se concluyó que los factores “estudio de mercado en el país de destino”, “clientes fidelizados”, “empaque perfecto”, “tener mayores ganancias” fueron los que impactaron más en la decisión de estas agro exportadoras para internacionalizar la palta Hass hacia un mercado tan competitivo como es Estados Unidos. / The objective of this research is to analyze each of the 4 dimensions of the Uppsala model, "recognition of opportunities", "position of the network of contacts", "learning, creation and construction of trust" and "decisions of commitment relationship ", Which are used by agricultural exporters to the United States of Hass avocado in Ica. Thus, finding different variables within these dimensions that are used to achieve the internationalization of Ica's agricultural exporter. The research approach is mixed, it began with a qualitative analysis where the in-depth interview was used as a tool, carried out with 6 experts to be able to validate the most outstanding variables within the 4 dimensions established in Uppsala. Then the quantitative analysis was carried out, where the tool that was used was a survey applied to the 10 agro-exporting companies of Hass avocado belonging to the total population of the investigation. We analyzed the results by applying the factor analysis model, which helped us find profiles of agricultural exporters for each dimension. The results obtained conclude that the dimensions "recognition of opportunities" and "learning, creation and construction of trust" of the Uppsala model are the most influential in the internationalization of the Hass avocado from agro-exporters from Ica. Likewise, it was concluded that the factors "market study in the destination country", "loyal customers", "perfect packaging", "having higher profits" were the ones that had the greatest impact on the decision of these agro-exporters to internationalize Hass avocado towards a market as competitive as the United States. / Tesis