A expansão agropecuária governa as mudanças no uso do solo no Brasil devido à alta demanda dos mercados interno e externo por alimento, fibra e energia. Entretanto, os efeitos e os processos decorrentes dessas alterações no ciclo hidrológico e na conservação do solo são pouco estudados de forma experimental em regiões de clima tropical e subtropical. No Estado de São Paulo, o uso do solo acontece de forma intensiva, as áreas de Cerrado nativo estão fragmentadas e pastagens vêm sendo substituídas por plantações de cana-de-açúcar devido à alta demanda por etanol e açúcar. Este trabalho tem como objetivo compreender as relações, trocas, variações e tendências das componentes do balanço hídrico e dos processos erosivos em potenciais mudanças no uso do solo que são encontradas no Sudeste do Brasil: de condições naturais (Cerrado sensu stricto) para pastagem, cana-de-açúcar e solo exposto. Para isso, foram monitorados, nos diferentes usos do solo, as condições meteorológicas, o escoamento superficial, a evapotranspiração, o conteúdo de água no solo, a erosão do solo e a flutuação do nível freático do aquífero. As alterações no uso do solo modificam significativamente o balanço hídrico, com aumento do escoamento superficial (pelo menos 14 mm ano-1) e diminuição da evapotranspiração (pelo menos 529 mm ano-1) quando o Cerrado sensu stricto é substituído por pastagem ou cana-de-açúcar. Entretanto, no Cerrado sensu stricto o volume de água disponível para percolação ao longo da zona não saturada e potencial recarga do aquífero tende a ser menor que em áreas agrícolas. As observações mostram que o solo exposto e a cana-de-açúcar possuem os maiores valores erosão do solo (16,00 ± 5,97 t ha-1 ano-1 e 0,64 ± 0,49 t ha-1 ano-1, respectivamente). Além disso, há semelhanças entre as taxas de perda de solo na pastagem (0,11 ± 0,04 t ha-1 ano-1) e no Cerrado sensu stricto (0,14 ± 0,06 t ha-1 ano-1). Devido às curtas séries de dados de escoamento superficial e erosão do solo, a adoção de modelos de base física como o WEPP (Water Erosion Prediction Project), é alternativa viável para simulações que considerem as variabilidades climáticas de regiões subtropicais. Projeções climáticas revelam que não ocorrerão alterações significativas nas respostas (escoamento superficial e erosão do solo) em relação ao clima base atual apesar do aumento significativo na precipitação nos cenários mais drásticos (entre 5% e 9%). Por fim, a manutenção do ciclo hidrológico e o controle da erosão do solo alcançados pelo Cerrado sensu stricto são benefícios que contrastam com a diminuição da recarga potencial do aquífero em áreas de vegetação densa. A cana-de-açúcar e a pastagem são usos do solo concorrentes e seus efeitos nos padrões hidrológicos e na erosão do solo se equilibram. / The agricultural expansion in Brazil drives land use changes due to the higher demand of internal and external markets for food, fiber and fuel. However, the effects and processes that result from these changes on hydrological cycle and soil conservation are not well explored in an experimental approach under tropical and subtropical climates. The land use is intense in the State of São Paulo, where the undisturbed woodlands in the Cerrado biome are fragmented and pasturelands are transformed in sugarcane plantations due to the higher sugar and ethanol demands. This thesis aims to comprehend the relations, trade-offs and variations of the water balance components and soil erosion processes under potential land use changes that can be found in southeastern Brazil: from natural landscapes (wooded Cerrado) to pastureland, sugarcane and bare soil. They were monitored in these different land uses: meteorological conditions, runoff, evapotranspiration, soil moisture content, soil erosion, and water table fluctuation. The land uses changes significantly influence the water balance, increasing the runoff (at least 14 mm yr-1) and decreasing evapotranspiration (at least 529 mm yr-1) when wooded Cerrado is substituted by pasture or sugarcane. Nevertheless, the soil water content available for deep percolation through the unsaturated zone and potential aquifer recharge in the wooded Cerrado tend to be smaller than in agricultural fields. Soil loss observations reveal that bare soil and sugarcane have the highest rates (16.00 ± 5.97 t ha-1 yr1 and 0.64 ± 0.49 t ha-1 yr-1, respectively). Additionally, there are similarities between the soil loss rates of pastureland (0.11 ± 0.04 t ha-1 yr-1) and wooded Cerrado (0.14 ± 0.06 t ha-1 yr-1). Due to the short-period observations of runoff and soil erosion, the use of a process-based model such as WEPP (Water Erosion Prediction Project) is a feasible alternative for simulations considering climatic variability under subtropical conditions. Projected climates reveal that in spite of significant increased rainfall (between 5% and 9%) in the most drastic scenarios, there are no significant changes on runoff and soil erosion rates in relation to the actual baseline climate. Finally, the hydrological stability and soil erosion control are benefits reached by the wooded Cerrado that contrast with the decrease in potential aquifer recharge in a dense vegetation area. Sugarcane and pasture are concurrent land uses and their effects on hydrological patterns and soil erosion are equivalent.

Anciennement espaces de production, les forêts intramétropolitaines ont été délaissées et peu considérées dans l’aménagement périurbain durant l’entre-deux guerres et les premières décennies d’après-guerre. L’exploitation des ressources naturelles et la création de lotissements résidentiels saisonniers puis permanents mitent dans l’indifférence les forêts, boisés et milieux humides des régions métropolitaines (Fortin et Després, 2009). La montée des préoccupations environnementales et l’émergence de nouvelles aspirations quant à la qualité du cadre de vie ont toutefois entrainé, dans les dernières années du 20e siècle, un changement de perspective. De nouvelles formes de valorisation ont été peu à peu prônées (Paquette, 2007; Donadieu et Périgord, 2005; Desprès et Fortin, 2009). Les qualités paysagères, récréatives et écologiques aujourd’hui associées aux espaces forestiers entrent dès lors en concurrence avec certaines activités et pratiques d’aménagement (Fortin et Després, 2009; Donadieu et Périgord, 2005). Dans cette perspective, ce travail de recherche s’intéresse au processus de transformation des valeurs sociales investies dans les espaces forestiers intramétropolitains, et plus précisément celui de la forêt de Terrebonne. L’analyse de différents documents d’archives (documents de planification, publicités, articles de journaux, etc.) a permis de faire ressortir les valeurs sociales portées par différents groupes d’acteurs et d’observer leurs transformations dans le temps. À la lumière des résultats obtenus, les années 1970 se sont révélées être celles de l’invention de la forêt comme espace de loisir à l’échelle régionale et de l’émergence des préoccupations sociales. Cette appropriation de la forêt par les résidents laisse place, 10 ans plus tard, à des revendications pour la protéger qui ne cesseront de prendre de l’importance au courant des années subséquentes. Au tournant des années 2000, la forêt devient un levier de valorisation territoriale pour les instances décisionnelles. La dernière décennie montre, quant à elle, l’émergence de la forêt écologique, une compréhension de plus en plus collective du milieu forestier qui lui octroie une valeur de support à la biodiversité et de milieu-levier contre les changements climatiques. Soulevant également l’omniprésence de valeurs écologiques dans le discours de la communauté locale à compter des années 2000, l’étude a permis de cerner l’utilisation de stratégies argumentaires destinées à renforcer les revendications en faveur de la protection de la forêt et de montrer l’importance de les étudier afin de mieux saisir les valeurs réellement investies à son égard. En somme, ce mémoire permet de mettre en lumière les impacts de la transformation des valeurs investies dans la forêt intramétropolitaine sur les pratiques d’aménagement ainsi que sur le discours promotionnel des promoteurs immobiliers et des instances municipales (municipalités et municipalités régionales de comté). / Intrametropolitan forests, often consisting of formerly productive land, were neglected from consideration in suburban and peri-urban development planning for several decades from the interwar period. Exploitation of natural resources and the creation of seasonal and permanent allotments proceeded with little regard for the forests, woodlands and wetlands of metropolitan regions (Fortin and Després, 2009). Since the late 20th century, environmental preoccupations and increasing aspirations for quality of the living environment have contributed to a change of perspective. New forms of awareness have gradually emerged (Paquette 2007; Donadieu and Perigord, 2005; Després and Fortin, 2009). The aesthetic, recreational and ecological qualities associated with wooded spaces is beginning to conflict with current practices (Fortin and Després, 2009; Donadieu and Périgord, 2005). Our research focuses on the transformation of the societal value invested in intrametropolitan forests, in particular that of the Terrebonne Forest. The analysis of archival material (planning documents, advertisements, newspaper articles, and similar) allows the values of different social groups to be identified and observed as they transform over time. In light of the results obtained, the 1970s appears to be the years of emergence of forest as a recreational space. It is also the period of the emergence of social concerns in regard of the natural environmental deterioration. Ten years later, this appropriation of the forest by the residents led them to demand its protection, and increasingly so over subsequent years. In the 2000s the forest became a lever for development for decision-making bodies. In the decade before 2020 the forested intrinsic ecological value has been recognized, due to its contribution to collective well-being, biodiversity, and its role addressing climate change. Raising the omnipresence of ecological values in the discourse of the local community from the 2000s, the study also made it possible to identify the use of argumentative strategies intended to reinforce the claims in favor of the protection of forest by the local community and the importance of studying them for a better understanding of the values actually invested in the forest. This thesis sheds light on the impacts of the transformation of the values invested in the forest on planning and development practices as well as on the promotional discourse of real estate developers, municipalities and MRC.