A Mata Atlântica é um dos biomas mais biodiverso e ameaçados do planeta. Grande parte de seus remanescentes está localizada no Vale do Ribeira (SP), onde se encontra a maioria das populações quilombolas do estado. Os quilombos do vale surgiram de povoados formados por escravos abandonados, fugidos e alforriados que vem ocupando o vale desde o início da colonização européia na região, no século XVI. A principal estratégia de subsistência destas populações ao longo dos séculos foi a coivara, sistema agrícola capaz de conferir grande heterogeneidade à paisagem florestal. Entretanto, nas últimas décadas, a coivara tem sofrido um processo de transformação, devido a fatores como: o aumento demográfico, o avanço da economia de mercado, a implantação de leis ambientais e políticas desenvolvimentistas. O objetivo deste estudo é compreender como a coivara contribuiu para a formação da paisagem florestal na comunidade de remanescente de quilombo de São Pedro, no vale do Ribeira. A construção de uma narrativa histórica dos processos que contribuíram para as transformações deste sistema auxilia na compreensão das mudanças nos padrões de subsistência locais e de que forma estas se refletem nessa paisagem. Para tanto, levantamos a memória social local, através de técnicas etnográficas e de história oral. Além disso, realizamos trilhas monitoradas para estudar a percepção ambiental das unidades paisagísticas, bem como a configuração espacial das roças e capoeiras. Com a aplicação de tais métodos, pudemos constatar que no passado, a abertura de clareiras para o cultivo dependia de uma série de fatores: a disponibilidade de capital social para o trabalho, a demanda familiar para a produção de alimento e as relações econômicas com o mercado regional. Ao mesmo tempo, a lógica de ocupação da paisagem era fruto da associação entre o conhecimento da dinâmica ecológica local e normas sociais estabelecidas. A unidade doméstica, composta pela casa de fora e pela capuova, foi a expressão material mais constante da agência humana na paisagem. Os processos de transformação da coivara se iniciaram na década de 1950, com a construção de rodovias e consequente diminuição do isolamento regional. A partir disso, a intensificação do corte de palmito e o estabelecimento da pecuária com a chegada dos grileiros, na década de 1970, levaram ao redirecionamento das atividades econômicas. Por consequência, ocorreu a diminuição da área das unidades agrícolas e do número de áreas sob cultivo. A partir da construção de uma escola no bairro, nos anos 70, ocorreu a concentração das residências em vila, que estimulou a concentração das unidades de cultivo ao redor. A intensificação da fiscalização ambiental na região, nos anos 80, passou a restringir as atividades locais de subsistência. Como resultado, observamos que duas tendências podem ser observadas atualmente: segmentação e homogeneização da paisagem em áreas destinadas ao manejo, por um lado, e o estabelecimento de uma formação de floresta madura, não mais passível de derrubada, por outro. Tal tendência pode resultar na diminuição da complexidade estrutural e da dinâmica ecológica da floresta local. Concluímos que, apesar da nova configuração espacial da coivara e da tendência à segmentação, a criação de pastagens e a extração de palmito parecem ser mais impactantes para a fragmentação da paisagem florestal. Por conta das mudanças levantadas, atualmente a população de São Pedro se depara com o desafio de combinar as restrições ambientais à necessidade de produzir itens com valor de mercado. Somado a isso, precisam reorganizar o trabalho coletivo e reformular a concepção local da paisagem e o seu uso para garantir, no futuro, sua permanência neste território. / The Atlantic Rainforest is one of the worlds most diverse and threatened biomes. The majority of its remnants are located at the Ribeira Valley (SP) where several of the States quilombola populations remain. The Valleys quilombos originated from a population of freed, abandoned or refugee slaves brought to the region in the beginning of the European colonization during the 16th century. The main subsistence strategy these populations have developed is the slash-and-burn agriculture (coivara), a system capable of proffering great heterogeneity to the forest landscape. However, the coivara system has been undergoing a transformation process in the last decades due to demographic increase, advance of the local economy and the implementation of environmental and political developmental legislation. The aim of this study is to understand how the coivara system has contributed to the forest landscape formation of the São Pedro quilombo community at the Ribeira Valley. A historic narrative of the processes that contributed to the systems transformation helps understand the changes in the local subsistence patterns and the way these changes reflect in the landscape. In order to do so, the local social memory was sought through ethnographic and oral history methods. Furthermore, monitored trails were carried out to study the environmental perception of landscape units and the spatial configuration of swidden and fallow plots. These methods allowed us to realize that, in the past, gap openings for crop cultures depended on a series of factors, such as: availability of social capital for labor, family demand on crop production, and economic ties with the regional market. Simultaneously, the landscape occupation was a product between the knowledge of the local ecological dynamics and the established social norms. The domestic unit, composed of the casa de fora and the capuova, was the most constant expression of human presence in the landscape. The coivara transformation processes began in the 1950s with road constructions decreasing the regions isolation. From then on, the intensification of palm-heart extraction and cattle ranching brought along with land grabbers in the 1970s, redirected the communities economic activities. As a consequence, both the number of cultivated areas and the area of each agricultural unit decreased. During the 70s, with the construction of a school in the region, the houses were displayed in a village form, which stimulated the concentration of cultivated units around it. Moreover, the intensification of environmental inspection in the region during the 80s restricted their local subsistence activities. As a result, two tendencies may be observed nowadays: segmentation and homogenization of the landscape into areas destined to management on one hand, and the establishment of a mature forest formation, unable to be cut down, on the other. This might result in a decrease of the structural complexity and ecological dynamics of the local forest. We conclude that, despite the new spatial configuration of the swidden plots and the tendency to segmentation, cattle grazing sites and palm-heart extraction seem to be most harmful, causing most of the forest landscape fragmentation. Due to these changes, the São Pedro community faces, nowadays, the challenge of combining their need to produce items with market value with the environmental restrictions brought upon them. Moreover, they must reorganize their collective labor activities and reformulate the local landscape conception and use to ensure, in the future, their permanence in that territory.

In this thesis natural science is combined with environmental psychology in order to determine how deforestation and subsequent agricultural expansion in the Peruvian highland jungle has affected the natural environment and rural livelihoods. This region is part of one of the most biodiverse areas on Earth and is also exposed to high pressure from deforestation that threatens the ecosystems as well as the well-being of local populations. The problem stretches beyond the upper Amazon since the region constitutes headwaters to theAmazon Riverand is part of the most important forest ecosystem of the world. This study evaluates the relative controls of human induced land-cover change and natural factors on the chemical status of soils, stream waters, and sediments, mainly through a spatial sampling design. The field work was located to two adjacent river basins underlain by sedimentary rocks. Streams of 48 independent sub-basins, the two main rivers, 80 upland soil sites (weakly developed soils on sandstone and siltstone) and four vertical profiles of floodplain sediments were sampled and analysed for major and trace elements, including nutrients and potentially toxic metals. Further, perceptions of environmental changes were investigated through a combination of quantitative and qualitative interview data collected from 51 smallholder farmers. Soils of primary forests were found to be chemically similar to those of regenerated forests and agricultural land-covers (pastures and coffee plantations), and differences in chemical concentrations between streams draining areas to varying degrees covered by forest were assigned to natural variability. In addition, the chemical composition of alluvial deposits was similar in the two drainage basins despite a substantial difference in exploitation degree (30 % versus 70 % cleared from forest). Thus, no evidence was found of long-term changes in the geochemistry of the Subandean river basins as a result of the conversion of primary forest to agricultural land-uses. The farmers, however, perceived an overall increase in environmental degradation as well as a change towards drier and warmer climatic conditions. The climate change was reported to be the main factor responsible for a negative trend in life quality (rural livelihoods). The results may be used in the work of identifying priorities and key factors necessary for environmental and socioeconomic sustainability in the upper Amazon. / En esta tesis se combina la ciencia natural con la psicología ambiental con el fin de determinar como la ampliación de la frontera agrícola ha afectado el medio ambiente y los medios de vida en la selva alta del Perú. Esta región forma parte de una de las zonas con mayor biodiversidad en el planeta y a su vez está expuesta a una alta presión de la deforestación que amenaza a los ecosistemas, así como el bienestar de la población en esta zona. Así mismo, este problema se hace sentir mas allá de la selva alta ya que esta zona forma parte de las cabeceras del río Amazonas y pertenece al ecosistema forestal más importante del mundo. Este estudio evalúa los efectos de la agricultura de tala y quema, en comparación con los factores naturales, sobre las propiedades químicas de los suelos, las quebradas, y los sedimentos, principalmente a través de un diseño de muestreo espacial. El trabajo de campo se realizó en dos cuencas fluviales adyacentes que están compuestas por rocas sedimentarias. Quebradas de 48 sub-cuencas independientes, dos ríos principales, 80 localidades de suelo (poco desarrollados sobre areniscas y limolitas) y cuatro perfiles verticales de sedimentos fluviales fueron muestreados y analizados para los elementos mayores y menores, incluyendo nutrientes y metales potencialmente tóxicos. También se han investigado las percepciones sobre los cambios ambientales usando una combinación de datos cuantitativos y cualitativos, recopilados a través de entrevistas a 51 agricultores. Según los resultados no hubo diferencias significativas entre la química de suelos de bosques primarios y tierras agrícolas (pastos, plantaciones de café y de bosques secundarios). En cuanto a las quebradas, las diferencias en las concentraciones de sustancias químicas entre sub-cuencas afectadas por la deforestación en diferentes grados fueron asignados a una variabilidad natural. Además, la composición química de los depósitos aluviales fue similar en las dos cuencas a pesar de una diferencia sustancial en el grado de explotación (30 % en comparación con 70 % deforestado). Por lo tanto, no se encontró evidencia de cambios persistentes en la geoquímica de las cuencas Subandinas como resultado de la conversión de bosques a tierras agrícolas. Sin embargo los agricultores percibieron una tendencia general de aumento de la degradación del medio ambiente, así como un cambio en el clima a condiciones más secas y cálidas, lo cual fue reportado como el principal factor responsable de un cambio negativo en la calidad de vida. Estos resultados pueden ser utilizados en el trabajo de identificación de prioridades y factores claves para la sostenibilidad ambiental y socioeconómica en la selva alta.

L’occupation du sol en zone forestière de Yangambi dans la Cuvette centrale congolaise (RDC) change rapidement et la fragmentation forestière liée à l’agriculture itinérante sur brûlis est devenue l’un des processus dominant la dynamique paysagère. La présente étude s’est fixée comme objectif de suivre une approche microclimatique en transects pour déterminer la zone de lisière entre les jachères herbeuses et les forêts denses, et ce, afin de mieux comprendre les réponses des propriétés physico-chimiques du sol aux changements d’occupation du sol et à la fragmentation forestière. Deux zones les plus appréciées par les paysans pour leurs exploitations agricoles ont été choisies en fonction des unités pédologiques existantes :la série Yangambi et la série Yakonde. Des échantillons non perturbés du sol de 0-10, 10-20 cm, 20-30 cm et perturbés de 0-20 cm ont été prélevés dans les différentes occupations de sols après la détermination de la zone de lisière. Notre démarche a consisté à comparer les propriétés de sols identiques au plan de leur pédogenèse, sous jachère herbeuse, sous lisière et sous couvert forestier, de façon à quantifier l’effet de lisière sur les propriétés des sols, pour mieux connaître les conséquences édaphiques de la fragmentation des forêts par l’agriculture itinérante sur brûlis. <p>Les résultats obtenus ont montré que la zone de lisière entre les jachères et les forêts denses a une largeur de 70 m pour la série Yangambi et 68 m pour la série Yakonde. Les variations microclimatiques de la lisière en terme de température de l’air, sont intermédiaires (moyenne, minima et maxima) entre celles des jachères herbeuses et des forêts denses. La fragmentation des forêts par l’agriculture itinérante sur brûlis modifie profondément les propriétés physico-chimiques de sols dans les couches superficielles. Un des effets de changements d’occupation du sol et de la fragmentation est la présence d’horizons superficiels à texture sableuse au niveau des jachères herbeuses et des lisières forestières. La densité apparente et la conductivité hydraulique ont subit une importante dégradation sous les jachères herbeuses. A l’inverse, la lisière forestière assure une bonne structure conservatrice du sol (faible densité apparente et bonne conductivité hydraulique). Le sol des forêts denses présente des bonnes propriétés physiques et de ce fait, est pris comme référence à partir duquel les effets de dégradation physique du sol peuvent être appréciés. <p>Le potentiel chimique du sol (pH, phosphore assimilable, le taux de saturation en bases et la CECE) est meilleur au niveau des jachères herbeuses et des lisières forestières par rapport aux forêts denses suite à la pratique du brûlis qui permet de restituer au sol une fraction de la minéralomasse forestière par les cendres. Les teneurs en carbone et azote totaux du sol ont été significativement plus élevées sous les lisières forestières que sous les jachères herbeuses et les forêts denses. Les résultats de l’indice de Kamprath ont montré que, les lisières, en plus de contribuer à l’accroissement de carbone organique du sol, tendent à diminuer la toxicité aluminique de sols étudiés. A l’inverse, l’étude a mis en évidence une toxicité aluminique plus élevée sous la jachère herbeuse de la série Yangambi que sous la lisière. En parallèle, nous avons observé une baisse des teneurs en fer sous toutes les jachères et les lisières forestières. <p>Les pratiques de jachères cultivées et d’agroforesterie s’avèrent incontournables pour enrichir ces sols en matière organique, limiter l’érosion liée au brûlis afin de freiner le lessivage des nutriments, éviter le compactage du sol et assurer le maintien à long terme d’une bonne structure conservatrice du sol.<p><p>In the forest zone of Yangambi, located in the Central Congo Basin (DRC), land use is changing rapidly and forest fragmentation due to slash and burn agriculture has become one of the dominant processes of landscape dynamics. This study's main goal is to apply a microclimatic approach in transects to determine the edge area between the fallow grasslands and dense forests, and, in order to better understand the responses of the soil physico-chemical properties to changes in land use and forest fragmentation. Two most popular areas used by farmers have been selected on the basis of the existing soil units: the Yangambi and Yakonde series. Undisturbed soil samples at depths of 0-10 cm, 10-20 cm, 20-30 cm and the disturbed at 0-20 cm were collected from different the land use types after detecting the edge area. Our approach was to compare the properties of identical soils based on their genesis, under grass fallow, edge and forest cover, so as to quantify the effect of edge on the soil properties, to better understand the edaphic consequences of the forest fragmentation by slash and burn shifting cultivation. <p>The results showed that the edge area between fallow and dense forests has a width of 70 m for the Yangambi series and 68 m for the Yakonde series. Microclimatic variations of the edge in terms of air temperature are intermediate (average, minimum and maximum) between grass fallows and dense forests. The fragmentation of forests by slash and burn shifting cultivation profoundly modifies the physico-chemical properties of soils in the surface layers. One of the effects of changes in land use and fragmentation was the presence of surface layers with more sandy texture in the fallow grassland and forest edges. Bulk density and hydraulic conductivity undergo an important degradation under grass fallows. In contrast, the forest edge ensures a maintenance of the soil structure (low bulk density and good hydraulic conductivity). Dense forest soil has thus good physical properties and therefore is taken as the reference from which the effects of soil physical degradation can be appreciated. <p>The chemical potential of the soil (based on pH, available phosphorus, base saturation and CECE) is better in the grass fallows and forest edges compared to dense forests due to the practice of slash and burn which allows restoration by adding nutrients to the soil through the ashes. The carbon and total nitrogen in the soil were significantly higher under forest edges than in fallow grasslands and dense forests. The results of the-Kamprath index shows the edges, in addition to contributing to an increase in soil organic carbon, tend to decrease the aluminium toxicity of studied soils. By contrast, the study revealed a higher aluminium toxicity under fallow grassland on the Yangambi series that under the edge and the forest. In parallel, we observed a decrease in iron contents in all fallow lands and forest edges. <p>The practices of cultivated fallows and agroforestry are proving unavoidable for enriching these soils in organic material, to reduce erosion related to slash and burn in order to curb the leaching of nutrients, to avoid soil compaction and to maintain a long-term well developed soil structure.<p><p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished