Este trabalho avaliou a função ecológica da diversidade arbórea em um agroecossistema partindo da hipótese de esta ser um instrumento significativo no manejo agrícola de pragas e doenças. Tendo a cultura da cana-de-açúcar como objeto de estudo, durante dois anos foi conduzido um experimento de campo no município de Mombuca - SP ao redor da mata do Pinheirinho, um fragmento florestal de porte e composição de vegetação de Mata Atlântica Estacional Semidecidual, cercado inteiramente por cultivos de cana-de- açúcar. O design experimental foi em Delineamentos Sistemáticos que permitiu a possibilidade de acompanhar os indicadores em pontos fixamente estabelecidos ao longo do tempo. Assim, foram delimitados 8 transectos de 100 metros de comprimento em sentidos cardeais a partir das bordas do fragmento florestal em direção aos talhões de cana-de-açúcar. Foram também demarcados seis pontos amostrais em situação de isolamento quanto à presença florestal, minimamente distantes em 300 metros de qualquer fragmento de porte significativo. O levantamento arbóreo na mata foi realizado através do método dos quadrantes. A riqueza em espécies raras foi avaliada e a diversidade arbórea foi determinada por índices de diversidade. A caracterização edáfica dos cultivos de cana foi realizada por meio de análises físico-químicas das amostras coletadas no início do estudo. As condições climáticas de temperatura e precipitação foram acompanhadas em todo o período do estudo. As informações sobre o cultivo e manejo da cana-de-açúcar no local foram disponibilizadas pelos técnicos e agricultores da usina e cooperativa que mantêm os talhões. A entomofauna na cultura foi monitorada mensalmente, durante seis meses em cada ano do estudo. Armadilhas do tipo Moericke foram instaladas em pontos amostrais estabelecidos de dez em dez metros nos 8 transectos e nos pontos isolados. Além da diversidade de insetos, foram analisados como indicadores de insetos-praga, a broca-da-cana (Diatraea saccharalis) e a cigarrinha-da-raiz (Mahanarva fimbriolata), e como indicadores de inimigo natural, parasitoides do gênero Paratheresia sp. (Diptera: Tachinidae). O indicador de doença foi o raquitismo da soqueira (Leifsonia xyli subsp. xyli), cujo nível de infestação foi monitorado nos dois anos do estudo. Os resultados obtidos foram interpretados após análise estatística específica para cada indicador. O fragmento florestal possui área de 214 hectares. Na amostragem da vegetação arbórea foram identificadas 67 espécies arbóreas entre 224 indivíduos amostrados. O índice de diversidade de Shannon foi de 3,04, de dominância de Simpson foi de 0,87 e as proporções de espécies e indivíduos raros foram, respectivamente, 0,42 e 0,43. A avaliação da entomofauna demonstrou efeito direto entre a distância da mata e a ocorrência de cigarrinha e broca da cana-de-açúcar. A distância da mata não interferiu na quantidade do parasitoide avaliado. A diversidade de insetos foi analisada após agrupamento das ordens coletadas em três diferentes grupos, separados conforme características biológicas e ecológicas das ordens. A proporção daqueles considerados potencialmente benéficos aumentou com a proximidade da mata. A proporção do grupo potencialmente misto (benéficos e prejudiciais) aumentou com a distância da mata. O número de indivíduos no grupo considerado potencialmente prejudicial não variou em função da distância da mata. A intensidade e infestação de raquitismo de soqueira teve aumento gradual e diretamente relacionado ao distanciamento das plantas cultivadas em relação ao fragmento florestal. / This work evaluated the ecological function of Arboreal Diversity in an agroecossystem based on the hypothesis that this is a significant instrument in the agricultural management of pests and diseases. After two years of cultivation of sugarcane as an object of study, a field experiment was carried out in the municipality of Mombuca, SP, around the Pinheirinho forest, a forest fragment of vegetation of the Atlantic Semideciduous Atlantic Forest, surrounded entirely by sugarcane crops. The experimental design was in Systematic Design that allowed the possibility of accompanying the indicators at fixed points established over time. Thus, eight 100-m-long transects were delineated in cardinal directions from the edges of the forest fragment toward the sugarcane fields. Six sample points were also demarcated in isolation from the forest presence, minimally distant at 300 meters from any significant fragment. The arboreal survey in the forest was done in quadrants. Wealth in rare species was evaluated and Arboreal Diversity was determined by diversity indexes. The edaphic characterization of the sugarcane crops was through physical-chemical analysis of the samples collected at the beginning of the study. Climatic conditions of temperature and precipitation were monitored throughout the period. Information on the cultivation and management of sugarcane in the site was made available by the technicians and farmers of the plant and cooperative that maintain the plots. The forest fragment has an area of 214 hectares, 67 tree species were identified in 224 individuals sampled. The diversity indexes were: Shannon 3.04; Simpson 0.87, the proportions of rare species and individuals were respectively 0.42 and 0.43. The evaluation of the entomofauna showed a direct effect between the distance of the forest and the occurrence of the sugar cane borer and the sugarcane borer. The distance from the forest did not interfere with the amount of parasitoid evaluated. The diversity of insects was analyzed after grouping the orders collected in three different groups according to the biological and ecological characteristics of the orders. The proportion of those considered potentially beneficial increased with the proximity of the forest. The proportion of the potentially mixed group (beneficial and harmful) increased with distance from the forest. The number of individuals in the group considered potentially harmful did not vary according to the distance of the forest. The intensity and infestation of ratoon rickets had a gradual increase and was directly related to the distancing of the cultivated plants in relation to the forest fragment.

Memoria para optar al título de Geógrafo / Diversos son los servicios ecosistémicos (SE) que se encuentran al margen del mercado, debido a su imposibilidad de ser considerados bienes transables y a su carácter de bien común, razón por la cual estos no son correctamente valorados por el análisis tradicional (oferta y demanda). La valoración de áreas naturales es una labor que no se limita a un análisis económico y a la cuantificación de los distintos SE, sino que además –al menos en el presente estudio- es un esfuerzo por ahondar en las prioridades de la población que es parte, en sus motivaciones y el propio valor que da, en relación al bienestar experimentado y vivido. Quebrada de la Plata, en Maipú, se caracteriza por poseer una gran biodiversidad –formando parte de un “hotspot” de biodiversidad- pero también recursos naturales apreciados por el mercado (minería), lo que ocasiono conflictos en torno al cuidado del lugar. Muchas son las aristas existentes en el presente estudio, aunque todas ellas van conducidas hacia un mismo objetivo, que es el contribuir en la conservación de Quebrada de la Plata, mediante una rearticulación en la relación de los diversos visitantes y entes involucrados al lugar, en un clima de respeto, educación, y empatía, teniendo a la conservación como la punta de flecha de las presentes y futuras acciones en la Quebrada. Sumándose además, la implementación del método de la disposición a pagar como una alternativa a aplicar al mediano plazo –posterior a la restauración del lugar, ya que actualmente no existen las condiciones para propiciar visitas de mayor peso al Santuario- que potencie al lugar como destino turístico de manera segura y controlada, y no como actualmente ocurre, en donde gran parte de las visitas al lugar ocurren de manera informal. / Various are the Ecosystemic Services (ES) found outside of the Economic Market, due to their impossibility to be considered sellable goods and to their character of common goods, reason for what these are not correctly valued by traditional analysis (offer and demand). The valuation of natural areas is a labor that is not limited to an economic analysis and to the quantification of the different ES, but moreover -at least in the present study- is an effort to go further in the priorities of the population from what it is part, in its motivations and the own given value, in relation to the experienced and lived wellness. Quebrada de la Plata, in Maipú (Chile), is characterized for possessing a great biodiversity –being part of a biodiversity hotspot- but also it possesses natural resources appreciated for the Economic Market (mining), what caused conflicts related to the care of the place. Many are the existing edges in the present study, although all they are driven to a same objective, to contribute to the conservation of Quebrada de la Plata, through a rearticulation in relation to the diverse visitors and entities involved to this place, in a climate of respect, education and empathy, with the conservation be the main objective of the present and future actions in Quebrada de la Plata. Adding moreover the method of the disposition to pay as an alternative to use in mid-term – later to a restoration of the place, because currently there are not conditions to promote most valuable visits to the sanctuary- to boost this place how a tourist destination in a sure and controlled way, and not how it currently happens, where the most of the visits to the place happen in an informal way. / Diversos são os serviços ecossistêmicos (SE) que estão fora do mercado, devido a sua impossibilidade de serem considerados como bens comercializáveis e seu caráter de bem comum, razão pela qual o valor disso não é equitativo em relação aos valores de mercado. A avaliação de áreas naturais é uma tarefa que não se limita a uma análise econômica e à quantificação dos diferentes SE, mas também - pelo menos no presente estudo - é um esforço para aprofundar as prioridades da população que faz parte, em suas motivações e no valor que dá, em relação ao bem-estar vivido. Quebrada de la Plata, no município de Maipú, caracteriza-se por sua grande biodiversidade -fazendo parte de um "hotspot" de biodiversidade- mas também de recursos naturais apreciados pelo mercado (mineração), que causou conflitos em torno dos cuidados do lugar. Muitas são as arestas existentes neste estudo, embora todas sejam voltadas para o mesmo objetivo, que é contribuir para a conservação da Quebrada de la Plata, através de uma rearticulação na relação dos diversos visitantes e entidades envolvidas no local, num clima de respeito, educação e empatia, com a conservação como ponta de lança das ações presentes e futuras na Quebrada. Adicionando, além disso, o método de disposição a pagar como alternativa a aplicar a médio prazo -Posterior ao restauro do lugar, visto que presentemente não existem condições para propiciar visitas de maior peso ao Santuário- que realce o lugar como destino turístico de forma segura e controlado, e não como acontece atualmente, onde grande parte das visitas ao site ocorre informalmente.

La moitié des forêts tropicales du monde est désignée comme des forêts de production par les services forestiers nationaux. Si l'effet de la déforestation sur les émissions de carbone et les pertes de biodiversité en région tropicale ont fait l'objet de nombreuses études, les impacts à long terme de l'exploitation commerciale de bois sur ces forêts restent à ce jour très peu étudiés. Or, les enjeux sont grandissants pour ces forêts de production. Non seulement elles doivent alimenter le commerce du bois tropical, mais leur rôle dans le stockage de carbone et dans la préservation de la biodiversité est de plus en plus reconnu. La thèse développée ici s'organise en trois temps. Premièrement, un modèle de bilan carbone de l'exploitation forestière est développé, et les différences régionales de dynamique de récupération du carbone post-exploitation sont modelisées. Deuxièmement, un modèle de récupération du volume de bois d'oeuvre a été développé et calibré à l'échelle amazonienne. Ces résultats ont permis de montrer la lenteur de la récupération du volume de bois d'Amazonie, et la non-durabilité des pratiques actuelles d'exploitation. Ces modèles (carbone et bois d'oeuvre) ont été élaborés dans un cadre bayésien, avec l'appui et les données du Tropical managed Forest Observatory (www.tmfo.org), réseau rassemblant 9 institutions de recherche et plus de 200 parcelles de suivi de la dynamique forestière après exploitation en Amazonie. Enfin, une analyse comparative de scénarios prospectifs a été effectuée, où les compromis possibles entre services écosystémiques (bois d'oeuvre, carbone et biodiversité) ont été explorés par des techniques d'optimisation multicritères. / Half of the world's tropical forets are designated by national forest services as production forests. While here have been numerous studies on the impact if devorestation on carbon emissions and biodiversity loss in the tropics, the long-term impacts of selective logging are still poorly studied; However, the importance of these production forests is increasing. Not only must they meet the growing tropical timber demand, but their role in Carbon storage and the biodiversity conservation is increasingly recognized. The studies developped in this thesis are threefold. First, a carbon balance model of logging is developped, and regional differences in post-logging carbon recovery of timber volume on the Amazon, and thus the unsustainability of current logging practices. These models (carbon and timber) were developped on a Bayesian framework, with support and data from the Tropical managed Forest Observatory (TmFO : www.tmfo.org), a netword of 9 research institutions and more than 200 forest plotswhere post-logging forest dynamics have been monitored for <30 years in the Amazon. Finally, a comparative analysis of prospective scenarios was carried out, where potential tradeoffs between ecosystem services (timber, carbone and biodiversity) were explored using multi-criteria optimization analysis.

Cette thèse interroge le statut juridique de la nature à travers une analyse théorique. Réfléchir sur le statut de la nature revient à questionner la singularité du lien qui lie l’homme à la nature : s’agit-il d’une mise en rapport induisant une échelle de valeur avec la hiérarchie qui l’accompagne, ou plutôt d’une mise en relation sans hiérarchie mais avec des liens d’interdépendance ? Finalement l’idée est de sortir d’une logique dualiste séparant l’homme de la nature. La nature est réifiée par le droit. Objet du droit, défini par et pour l’homme, elle est qualifiée de chose, de bien ou encore de patrimoine. Mais cette thèse est avant tout le constat d’une évolution du statut de la nature, qui ne peut plus être considérée aujourd’hui seulement comme un objet. L’évolution socio-politique accompagne un mouvement tendant à sa subjectivisation progressive. S’opère alors un rééquilibrage « désacralisant » l’homme quand il persiste à se couper du reste de la nature / This thesis questions the legal status of nature through a theoretical analysis. Reflecting on the status of nature is tantamount to questioning the singularity of the link between man and nature: is it a relationship that induces a scale of value with a subsequent hierarchy, or rather a relationship without hierarchy but with links of interdependence? Eventually, the idea is the idea is to escape from a dualistic logic separating man from nature. Nature is first reified by law. Object of law, defined by and for men, nature is considered as a thing, a good or an heritage. But this thesis is above all the observation of an evolution of the status of nature which can no longer be considered today only as an object. The socio-political evolution accompanies a movement aiming at the progressive subjectivization of nature. A rebalancing then occurs, "desacralizing" man as he persists in cutting himself from the rest of nature

La modélisation dynamique des systèmes écologiques constitue une méthode incontournable pour comprendre,prédire et contrôler la dynamique des écosystèmes semi-naturels, qui fait intervenir des processuscomplexes. Le principal objectif de cette thèse est de développer un modèle permettant de simuler la dynamiqueà moyen terme de la végétation herbacée dans les prairies permanentes, en tenant compte à lafois de la productivité et de la biodiversité. Les prairies sont des réservoirs présentant une forte biodiversitévégétale, qui soutiennent de nombreux services écosystémiques. Sur le plan agricole, cette importantediversité contribue à la qualité de la production fourragère, et de plus, elle permet une plus grande résistancede la végétation face à des changements climatiques (réchauffement moyen, vagues de chaleur etde sécheresse).Pourtant, cette notion clé de biodiversité n’est que faiblement prise en considération dans la modélisationde l’écosystème prairial : elle est souvent absente ou alors présente sous une forme très simplifiée. Enréponse à ces considérations, ces travaux de thèse présentent la construction d’un modèle de successionbasé sur des processus, décrit par un système d’équations différentielles ordinaires, qui représente ladynamique de la végétation aérienne des prairies tempérées. Ce modèle intègre les principaux facteursécologiques impactant la croissance et la compétition des espèces herbacées, et peut s’ajuster à n’importequel niveau de diversité, par le choix du nombre et de l’identité des espèces initialement présentes dansl’assemblage. Ce formalisme mécaniste de modélisation nous permet alors d’analyser les relations qui lientdiversité, productivité et stabilité, en réponse à différentes conditions climatiques et différents modes degestion agricole.[...]Ces résultats soulignent alors le besoin de prendre en compte le rôle clé joué par la biodiversité dansles modèles de l’écosystème prairial, de par son impact sur le comportement des dynamiques simulées.De plus, pour rendre correctement compte des interactions au sein de la végétation, le nombre d’espècesconsidéré dans le modèle doit être suffisamment important. Enfin, nous comparons les simulations devégétation de ce modèle à des mesures issues de deux sites expérimentaux, la prairie de fauche d’Oensingen,et le pâturage de Laqueuille. Les résultats de ces comparaisons sont encourageants et soulignentla pertinence du choix et de la représentation des processus écologiques clés qui composent ce modèlemécaniste.Ce travail de thèse propose donc un modèle, en total adéquation avec les besoins actuels en terme demodélisation de l’écosystème prairial, qui permet de mieux comprendre la dynamique de la végétationherbacée et les interactions entre productivité, diversité et stabilité. / Dynamic modelling of ecological systems is an essential method to understand, predict and control thedynamics of semi-natural ecosystems, which involves complex processes. The main objective of this PhDthesis is to develop a simulation model of the medium- and long-term dynamics of the herbaceous vegetationin permanent grasslands, taking into account both biodiversity and productivity. Grasslandecosystems are often hot spots of biodiversity, which contributes to the temporal stability of their services.On an agricultural perspective, this important biodiversity contributes to the forage quality, andbesides, it induces a higher ability of the vegetation cover to resist to different climatic scenarios (globalwarming, heat and drought waves).However, this key aspect of biodiversity is only poorly included in grassland models : often absent ofmodelling or included in a very simple form. Building on those considerations, this PhD work exposes thewriting of a process-based succession model, described by a system of Ordinary Differential Equationsthat simulates the aboveground vegetation dynamics of a temperate grassland. This model implementedthe main ecological factors involved in growth and competition processes of herbaceous species, and couldbe adjust to any level of diversity, by varying the number and the identity of species in the initial plantcommunity. This formalism of mechanistic models allows us to analyse relationships that link diversity,productivity and stability, in response to different climatic conditions and agricultural management.In mathematical grassland models, plant communities may be represented by a various number of statevariables, describing biomass compartments of some dominant species or plant functional types. The sizeof the initial species pool could have consequences on the outcome of the simulated ecosystem dynamicsin terms of grassland productivity, diversity, and stability. This choice could also influence the modelsensitivity to forcing parameters. To address these issues, we developed a method, based on sensitivityanalysis tools, to compare behaviour of alternative versions of the model that only differ by the identityand number of state variables describing the green biomass, here plant species. This method shows aninnovative aspect, by performing this model sensitivity analysis by using multivariate regression trees. Weassessed and compared the sensitivity of each instance of the model to key forcing parameters for climate,soil fertility, and defoliation disturbances. We established that the sensitivity to forcing parameters ofcommunity structure and species evenness differed markedly among alternative models, according tothe diversity level. We show a progressive shift from high importance of soil fertility (fertilisation level,mineralization rate) to high importance of defoliation (mowing frequency, grazing intensity) as the sizeof the species pool increased.These results highlight the need to take into account the role of species diversity to explain the behaviourof grassland models. Besides, to properly take into account those interactions in the grassland cover, theconsidered species pool size considered in the model needs to be high enough. Finally, we compare modelsimulations of the aboveground vegetation to measures from two experimental sites, the mowing grasslandof Oensingen, and the grazing grassland of Laqueuille. Results of these comparison are promising andhighlight the relevance of the choice and the representation of the different ecological processes includedin this mechanistic model.Thus, this PhD work offers a model, perfectly fitting with current needs on grassland modelling, whichcontribute to a better understanding of the herbaceous vegetation dynamics and interactions betweenproductivity, diversity and stability.