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Shifting cultivation is considered to be a key cause of deforestation in the tropics as agriculturalists transform the rain forest into cropland and later allow for its regeneration through fallowing. Forest fallows strongly influence the ecological and economic potential of shifting cultivation, yet, secondary forest management among shifting cultivators remains poorly understood. This study focuses on secondary forest management among peasant households in a land-abundant ejido, near the Calakmul Biosphere Reserve of Mexico. Data were gathered through in-depth household interviews and field visits with 44 households, accounting for more than 450 fields. Striking differences were found in fallowing practices in Nuevo Becal. The holding of secondary forest is related to access to male labour, wealth in land-assets, household age, and the holding of pasture. Fallow length at the plot level is associated with household age, land holding size and the manner in which land is acquired. Fallow periods tend to be longer for cycles begun from primary forest and appear to have become longer over time. This study demonstrates the importance of the microdynamics that influence differential land use decisions among households under apparently similar environmental and macroeconomic conditions.

Orientadora: Profª. Drª. Helena França / Coorientador. Prof. Dr. Leandrro Reverberi Tambosi / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia Ambiental, Santo André, 2018. / Esse trabalho objetivou mapear e quantificar a agricultura itinerante praticada pelas populações tradicionais caiçaras na região do atual Parque Estadual do Prelado (PEP), uma das unidades de conservação do Mosaico de Unidades de Conservação Juréia-Itatins (MUCJI), situado na região litorânea sul do estado de São Paulo, entre 1962 e 2011. Fotografias aéreas de 1962, 1972, 1981, 2000 e 2011 foram digitalizadas, ortorretificadas e interpretadas em Sistema de Informações Geográficas (SIG). As roças foram mapeadas e quantificadas em relação ao número e área. Constatou-se que 12,4% da área do PEP foi manejada pela agricultura, e que os 87,6% restantes não foram usados para essa atividade nos últimos 60 anos. As áreas cultivadas estavam distribuídas pelas bordas do Parque, sobre a Floresta Ombrófila Densa de Terras Baixas, próximas às estradas e rios, mesmo que distantes das unidades domésticas. No ano de 2011, 95% da área que havia sido utilizada previamente para agricultura estava regenerada como floresta, e apenas 0,05% da área total do PEP permanecia como roça. A análise indicou que 40% das áreas manejadas não apresentaram a classe de roças em nenhum mapeamento dos anos estudados, sugerindo que essas áreas só foram cultivadas nas décadas anteriores a 1960; nos 60% restantes, ou houve cultivo por duas ou mais décadas, ou o pousio foi inferior a 10 anos. A agricultura itinerante, que vinha diminuindo desde a década de 1960, apresentou ruptura praticamente definitiva após a criação da unidade de conservação em 1986. / The purpose of this work is to map and quantify the shifting cultivation practiced by traditional communities caiçaras in the region of Prelado State Park (PEP), one of the units of the Juréia-Itatins Conservation Units Mosaic (JICUM) located in the southern coastal region of the state of São Paulo between 1962 and 2011. Aerial photographs from 1962, 1972, 1981, 2000 and 2011 were scanned, orthorectified and interpreted in a Geographic Information System (GIS). The plots were mapped and quantified in relation to the number and area. It was found that 12.4% of the PEP area was managed by traditional practices of shifting cultivation, and that the remaining 87.6% was not used for this activity in the last 60 years. The cultivated areas were distributed along the edges of the Park, over the Dense Ombrophilous Forest of the Coastal Plain, close to the roads and rivers, even if far from the houses. In 2011, 95% of the area that had previously been used for shifting cultivation was regenerated as forest, and only 0.05% of the total area of the PEP remained as a traditional agriculture. The analysis has indicated that 40% of the areas which were managed by traditional agriculture was not cultivated prior to 1960; in the remaining 60%, there was no agricultural management for two or more decades, or perhaps there was fallow for less than 10 years. Shifting cultivation, which was decreasing since the 1960s, suffered a definitive rupture after the creation of the protected area Jureia-Itatins Ecological Station in 1986 (later converted in JICUM).

No description available.

No description available.

O presente trabalho teve por objetivo compreender a dinâmica do manejo da agrobiodiversidade nos roçados de mandioca em comunidades ribeirinhas de várzea e terra firme das Reservas de Desenvolvimento Sustentável Amanã e Mamirauá, na Amazônia, e suas relações com as formas de organização da produção, do espaço e do trabalho adotadas pelos produtores. Para tal foi trabalhado um conjunto de metodologias baseados na teoria de sistemas agrários, análise de agroecossistemas, etnoecologia e análise genética utilizando microssatélites. Os resultados indicaram que: 1) Nas duas reservas existem três identidades produtivas, forjadas a partir da principal fonte de renda: agricultores, pescadores e agricultores-pescadores (desenvolvem as duas atividades com fins de comercialização); 2) Os ribeirinhos classificam diversos ambientes como aptos para a agricultura, e a partir deles diversos sistemas de cultivo, que variam em função do ecossistema (várzea ou terra-firme); 3) Existem duas racionalidades produtivas na agricultura (comercialização e auto-consumo), que moldam as racionalidades de manejo da agrobiodiversidade; 4) A diversidade específica e varietal nos roçados diminui à medida que se aumenta o grau de especialização produtiva, tanto da pesca, quanto da agricultura. Contudo, isso não se verifica do ponto de vista genético, uma vez que os genes estão bem distribuídos nas variedades e populações, independente da lógica produtiva; 5) Os roçados de mandioca da RDS Amanã e RDS Mamirauá são extremamente diversos geneticamente, apresentando altos valores de riqueza alélica, polimorfismo e heterozigosidade; 6) A diversidade genética está estruturada basicamente dentro de cada roçado, o que indica alto fluxo gênico entre as variedades de cada roçado e entre as variedades dos diferentes roçados, proporcionada principalmente pela troca de variedades entre agricultores, diminuindo a diferença entre roçados e aumentando a freqüência de diferentes alelos em cada roçado; 7) Os pescadores e as comunidades de várzea têm papel fundamental na dinâmica da agrobiodiversidade, pois abrigam grande número de espécies e variedades de mandioca nos roçados; 8) Portanto, em todas as comunidades a agricultura tem papel fundamental, o que denota que as estratégias de assessoria devem prever a dimensão de sistemas de produção em suas intervenções. / This study had the objective of understanding the agrobiodiversity management dynamics in roçados (swidden fields of cassava) in riverine communities of the Amanã and Mamirauá Sustainable Reserves in the Amazon and its relations with production, space and work management adopted by the families. The methodology adopted was based on the agrarian systems theory, agroecosystems analysis, ethnoecology and microsatellites genetic analysis. The results indicated that: 1) In the two reserves there are three productive identities, forged from the main source of economic income: agriculturists, fishing and agriculturist-fishing (they develop the two activities with commercialization aims); 2) The informers classify diverse environments as apt for agriculture, and from them diverse crop systems, that vary in function of the ecosystem (land-firm or floodplain); 3) There are two productive rationalities in agriculture (commercialization and self-consumption), which adapts to the rationalities of agrobiodiversity management; 4) The specific and varietal diversity in the roçados decreases as the level of productive specialization increases, both the fishing and agriculture. However, this is not verified in the genetic point of view, where the genes are well distributed in the varieties and populations, independent of the productive logic; 5) The roçados at the Amanã and Mamirauá SDR are extremely diverse, presenting high values of allelic diversity, polymorphism and heterozigosity; 6) The genetic diversity is structured basically within each roçado, which indicates high gene flow among the varieties of each roçado and among the varieties of the different roçados, promoted mainly by the exchange of varieties between agriculturists, diminishing the difference between roçados and increasing the frequency of different alleles in each roçado; 7) The floodplain fishing and communities have an important role in the agrobiodiversity dynamics, as they shelter a great number of species and cassava varieties in their roçados; 8) Therefore, in all the communities agriculture has an important role, which denotes that the extension strategies must foresee the production systems approach in their interventions.

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Wild plant resources are harvested and managed by people in a variety of land-uses but few studies examine the interactions of landscape dynamics and the use and availability of wild plant resources. I address this question using a case study of common property lands with a history of community forestry and traditional shifting cultivation. Specifically I ask: What is the perceived importance of plant resources obtained in agricultural and forest environments? Have forest and agricultural land-use/land covers changed? How do landscape changes, and in particular shorter fallow times, influence the availability and use of plant resources? / The perceived importance of wild plant resources was studied using free-listing and ranking exercises with focus groups of men and women. Remote sensing and interviews served to analyse landscape dynamics (1976-2000) and to identify local forest conservation regulations. The impact of shorter fallow times on the availability of forage and firewood in agricultural fields was assessed by sampling 26 fields derived from short to long fallows, while a household survey served to characterize patterns of firewood collection. / Men attributed highest importance to commercial forest products, while resources most valued by women were domestic resources obtained in a variety of environments. High rates of forest retention were observed; conservation was focused on forests with high densities of commercial products. The agricultural zones shifted from a mosaic of diverse successional stages to a homogeneous landscape dominated by younger fallows and shorter fallow periods; these changes led to reductions in the availability of firewood and some forage species. Firewood collection was related to accessibility; areas with the least amount of firewood available (short-fallow cycles and low forest cover) experienced the highest collection pressure. / The findings demonstrate that indigenous territories can be very dynamic, even when rates of forest conservation are high, and that changes in land-use and landscape structure have important implications for the availability and use of wild plant resources. A conceptual model linking landscape dynamics to wild plant use is proposed and the significance of the results for community-based conservation initiatives is discussed.

O presente trabalho teve por objetivo compreender a dinâmica do manejo da agrobiodiversidade nos roçados de mandioca em comunidades ribeirinhas de várzea e terra firme das Reservas de Desenvolvimento Sustentável Amanã e Mamirauá, na Amazônia, e suas relações com as formas de organização da produção, do espaço e do trabalho adotadas pelos produtores. Para tal foi trabalhado um conjunto de metodologias baseados na teoria de sistemas agrários, análise de agroecossistemas, etnoecologia e análise genética utilizando microssatélites. Os resultados indicaram que: 1) Nas duas reservas existem três identidades produtivas, forjadas a partir da principal fonte de renda: agricultores, pescadores e agricultores-pescadores (desenvolvem as duas atividades com fins de comercialização); 2) Os ribeirinhos classificam diversos ambientes como aptos para a agricultura, e a partir deles diversos sistemas de cultivo, que variam em função do ecossistema (várzea ou terra-firme); 3) Existem duas racionalidades produtivas na agricultura (comercialização e auto-consumo), que moldam as racionalidades de manejo da agrobiodiversidade; 4) A diversidade específica e varietal nos roçados diminui à medida que se aumenta o grau de especialização produtiva, tanto da pesca, quanto da agricultura. Contudo, isso não se verifica do ponto de vista genético, uma vez que os genes estão bem distribuídos nas variedades e populações, independente da lógica produtiva; 5) Os roçados de mandioca da RDS Amanã e RDS Mamirauá são extremamente diversos geneticamente, apresentando altos valores de riqueza alélica, polimorfismo e heterozigosidade; 6) A diversidade genética está estruturada basicamente dentro de cada roçado, o que indica alto fluxo gênico entre as variedades de cada roçado e entre as variedades dos diferentes roçados, proporcionada principalmente pela troca de variedades entre agricultores, diminuindo a diferença entre roçados e aumentando a freqüência de diferentes alelos em cada roçado; 7) Os pescadores e as comunidades de várzea têm papel fundamental na dinâmica da agrobiodiversidade, pois abrigam grande número de espécies e variedades de mandioca nos roçados; 8) Portanto, em todas as comunidades a agricultura tem papel fundamental, o que denota que as estratégias de assessoria devem prever a dimensão de sistemas de produção em suas intervenções. / This study had the objective of understanding the agrobiodiversity management dynamics in roçados (swidden fields of cassava) in riverine communities of the Amanã and Mamirauá Sustainable Reserves in the Amazon and its relations with production, space and work management adopted by the families. The methodology adopted was based on the agrarian systems theory, agroecosystems analysis, ethnoecology and microsatellites genetic analysis. The results indicated that: 1) In the two reserves there are three productive identities, forged from the main source of economic income: agriculturists, fishing and agriculturist-fishing (they develop the two activities with commercialization aims); 2) The informers classify diverse environments as apt for agriculture, and from them diverse crop systems, that vary in function of the ecosystem (land-firm or floodplain); 3) There are two productive rationalities in agriculture (commercialization and self-consumption), which adapts to the rationalities of agrobiodiversity management; 4) The specific and varietal diversity in the roçados decreases as the level of productive specialization increases, both the fishing and agriculture. However, this is not verified in the genetic point of view, where the genes are well distributed in the varieties and populations, independent of the productive logic; 5) The roçados at the Amanã and Mamirauá SDR are extremely diverse, presenting high values of allelic diversity, polymorphism and heterozigosity; 6) The genetic diversity is structured basically within each roçado, which indicates high gene flow among the varieties of each roçado and among the varieties of the different roçados, promoted mainly by the exchange of varieties between agriculturists, diminishing the difference between roçados and increasing the frequency of different alleles in each roçado; 7) The floodplain fishing and communities have an important role in the agrobiodiversity dynamics, as they shelter a great number of species and cassava varieties in their roçados; 8) Therefore, in all the communities agriculture has an important role, which denotes that the extension strategies must foresee the production systems approach in their interventions.

It is evident that Ethiopia is one of the countries of Africa that is experiencing significant population growth as well as land use/cover dynamics. Land use/cover induced degradation of natural resources is a major challenge to the country’s development. The main objective of this study was to investigate the impact population dynamics has had on land use/cover in Mandura district. Data on population over time were taken from the CSA during the 1984, 1994 and 2007 national census results. A total of 210 farm households from three kebeles: 105 from the local people and 105 from migrants were surveyed in May 2011 to acquire data on socioeconomic, land use, resource use and management. Aerial photographs of 1957, 1982 and SPOT-5 image of the 2006/07 were used to generate data on land use/cover changes. The results indicate that population has substantially increased, more than fourfold between 1957-2006/07, mainly due to migration from the surrounding areas, government sponsored resettlements, and flourishing of new urban centers. No less important is mortality has decreased due to immunization and the birth rate has been increasing due to improved maternal and child care as compared to the situation prior to the 1990s. The change on land use/cover show that from the total land use/cover conversions, which totals 58,403 ha of land, farm land constitutes 90.1 %. The study finds natural population increase, migration, urbanization, agricultural extensification, institutional weakness, land tenure insecurity, famine and drought, and poverty as root causes. The study further identifies existence of all weather road, resettlement, Tana-Beles project, expansion of agriculture, land colonization, wood extraction for fuel, and soil fertility decline as direct causes of land use/cover changes. As a result of change of customary land tenure system, the local population has been forced to engage in extractive economic activities that have never been practiced in the past. Therefore, the study calls for coordinated efforts for resources use and management at different levels, land use policy formulation, devising alternative sources of livelihoods and fuel, regulating migration and involvement of the wider community in policy formulation and implementations. / Geography / D. LITT. et. Phil. (Geography)