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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

O papel de sistemas agroflorestais para a conectividade em paisagem fragmentada do nordeste do Rio Grande do Sul

Hassdenteufel, Clarissa Britz January 2010 (has links)
Esse estudo teve como objetivo comparar duas formas de manejo de cultivos de banana em relação ao seu potencial de abrigar espécies florestais. Nós assumimos que o registro de espécies florestais utilizando um elemento da matriz mostra que a espécie não evita a matriz totalmente e pode ser capaz de cruzá-la, indicando a importância dessas estruturas para a manutenção de conectividade funcional entre as áreas de hábitat. Foram amostrados 30 cultivos incluindo áreas sob manejo convencional e agroflorestal. Em cada unidade amostral foram realizadas transecções para acessar a proporção de aves florestais, generalistas e de áreas abertas. Variáveis descritoras da estrutura interna e da estrutura da paisagem do entorno dos cultivos foram consideradas para verificar se a avifauna responde à características intrínsecas dos cultivos ou ao contexto de paisagem em que os cultivos estão inseridos. A proporção de espécies florestais foi maior em cultivos agroflorestais (F28;0,001=19,29; p<0,0004), enquanto a proporção de generalistas não apresentou diferença significativa (F28;0,001=0,22; p<0,22) e a de espécies de áreas abertas foi maior em cultivos convencionais (F28;0,001=8,92; p<0,006). Os dois conjuntos de variáveis considerados, isto é, a estrutura interna do cultivo e do entorno deste foram importantes para predizer a proporção de espécies florestais. Embora tenhamos observado o efeito da paisagem na proporção de espécies florestais, salientamos aqui que sistemas convencionais, mesmo em contextos de paisagem similares à sistemas agroflorestais, não apresentaram a mesma proporção de espécies florestais. Esse resultado indica um diferencial de cultivos agroflorestais de banana para a ocorrência de espécies florestais. Em nível de paisagem, a proporção de florestas e consequentemente a diminuição do isolamento entre manchas é o responsável pela presença potencial de espécies em fragmentos. No entanto, em nível de mancha, mesmo esta apresentando um contexto de paisagem favorável para que seja ocupada por espécies de áreas fonte, o mecanismo que influencia a presença das espécies é a elevada estrutura interna dos bananais. / This study aimed to compare two management of banana crops in relation to its potential to host forest bird species. We assume that the record of forest bird species using a matrix element shows that the species does not entirely avoid this area and may be able to cross it, indicating the importance of these structures for the maintenance of functional connectivity between areas of habitat. We sampled 30 areas including crops under conventional and agroforestry management. In each sampling unit we used transects to access the composition and abundance of bird species. Descriptive variables of the internal structure and the structure of the surrounding landscape of crops were considered to determine whether the bird responds to the intrinsic characteristics of the crops or the landscape context in which crops are inserted. The proportion of forest species was higher in agroforestry crops (F28, 0,001 = 19.29, p <0.0004), while the proportion of generalists showed no significant difference (F28, 0,001 = 0.22, p <0.22) and species of open areas was greater in conventional crops (F28, 0,001 = 8.92, p <0.006). The two sets of variables considered, i.e. the internal structure of the crop and of surroundings, were important to predict the proportion of forest birds species. Although we observed the effect of landscape in the proportion of forest species, we note here that conventional systems, even in contexts similar to the landscape agroforestry systems, did not show the same proportion of forest species. This result indicates a upper value of agroforestry crops for the occurrence of forest bird species. At landscape level, the proportion of forests and consequently the lower isolation between patches is responsible for the potential presence of species in fragments. However, at patch level, even it is presenting a landscape context favorable to be occupied by a species of source areas, the mechanism that influences the presence of the species is the high internal structure of the banana plantations.
242

Desempenho de forrageiras anuais de inverno sob distintos níveis de irradiância

Kirchner, Roque 12 February 2009 (has links)
O trabalho objetivou determinar possíveis efeitos na produção e qualidade de forragem das espécies anuais de inverno: aveia preta (Avena strigosa schreb) cv. comum, aveia branca (Avena sativa L) cv. Fapa 2, azevém (Lolium multiflorum L,) cv. comum, Trigo (Triticum aestivum L. ) duplo propósito cv. BRS Tarumã, ervilhaca peluda (Vicia villosa), em função de três diferentes níveis de irradiância (luminosidade): a) nível céu aberto com 100% de irradiância; b) nível 15x3 com 70% de irradiância e 222 árvores de Pinus taeda/ha e c) nível 9x3 com 21% de irradiância e 370 árvores de Pinus taeda/ha O delineamento experimental foi de blocos completos ao acaso, em parcelas subdivididas e três repetições. O azevém foi a espécie mais produtiva em todos os níveis de irradiância, embora a ervilhaca tenha a menor redução de produção quando sombreada. Houve maior potencial hídrico nas plantas e maior umidade no solo, em ambientes sombreados, mesmo assim a produção de forragem foi drasticamente reduzida (81%) no nível de menor irradiância. O teor de proteína bruta (PB) aumentou, enquanto os nutrientes digestíveis totais (NDT) diminuíram da maioria das espécies estudadas em ambientes com menores níveis de irradiância. Os níveis de irradiância não influenciaram os teores de K. / This study aimed to determine possible effects in forage production and quality of the following annual winter forage: black oat (Avena strigosa Schreb) cv. Common, white oat (Avena sativa L.) cv. FAPA 2, ryegrass (Lolium multiflorum L,) cv. common, hairy vetch (Vicia villosa), wheat (Triticum aestivum L.) cv. dual purpose. BRS Tarumã under three different levels of irradiance (luminosity): a) full sunlight with 100% of irradiance b) level of 15x3 with 70% of irradiance and 222 trees per hectare and c) level of 9x3 with 21% of irradiance, with 370 trees/ha. The experimental design was completely randomized blocks, with split plots and three replicates. The ryegrass presented the highest production to all the irradiance levels, although the vetch presented the lower dry matter reduction under shading. There was higher water potential in plants and higher soil moisture under shading, however, forage production was strongly diminished (81%) at the lower irradiance levels. The crude protein increased while the total digestible nutrients decreased to most of the studied species in environment with lower levels of irradiance. The irradiance levels did not influenced the K content.
243

O papel de sistemas agroflorestais para a conectividade em paisagem fragmentada do nordeste do Rio Grande do Sul

Hassdenteufel, Clarissa Britz January 2010 (has links)
Esse estudo teve como objetivo comparar duas formas de manejo de cultivos de banana em relação ao seu potencial de abrigar espécies florestais. Nós assumimos que o registro de espécies florestais utilizando um elemento da matriz mostra que a espécie não evita a matriz totalmente e pode ser capaz de cruzá-la, indicando a importância dessas estruturas para a manutenção de conectividade funcional entre as áreas de hábitat. Foram amostrados 30 cultivos incluindo áreas sob manejo convencional e agroflorestal. Em cada unidade amostral foram realizadas transecções para acessar a proporção de aves florestais, generalistas e de áreas abertas. Variáveis descritoras da estrutura interna e da estrutura da paisagem do entorno dos cultivos foram consideradas para verificar se a avifauna responde à características intrínsecas dos cultivos ou ao contexto de paisagem em que os cultivos estão inseridos. A proporção de espécies florestais foi maior em cultivos agroflorestais (F28;0,001=19,29; p<0,0004), enquanto a proporção de generalistas não apresentou diferença significativa (F28;0,001=0,22; p<0,22) e a de espécies de áreas abertas foi maior em cultivos convencionais (F28;0,001=8,92; p<0,006). Os dois conjuntos de variáveis considerados, isto é, a estrutura interna do cultivo e do entorno deste foram importantes para predizer a proporção de espécies florestais. Embora tenhamos observado o efeito da paisagem na proporção de espécies florestais, salientamos aqui que sistemas convencionais, mesmo em contextos de paisagem similares à sistemas agroflorestais, não apresentaram a mesma proporção de espécies florestais. Esse resultado indica um diferencial de cultivos agroflorestais de banana para a ocorrência de espécies florestais. Em nível de paisagem, a proporção de florestas e consequentemente a diminuição do isolamento entre manchas é o responsável pela presença potencial de espécies em fragmentos. No entanto, em nível de mancha, mesmo esta apresentando um contexto de paisagem favorável para que seja ocupada por espécies de áreas fonte, o mecanismo que influencia a presença das espécies é a elevada estrutura interna dos bananais. / This study aimed to compare two management of banana crops in relation to its potential to host forest bird species. We assume that the record of forest bird species using a matrix element shows that the species does not entirely avoid this area and may be able to cross it, indicating the importance of these structures for the maintenance of functional connectivity between areas of habitat. We sampled 30 areas including crops under conventional and agroforestry management. In each sampling unit we used transects to access the composition and abundance of bird species. Descriptive variables of the internal structure and the structure of the surrounding landscape of crops were considered to determine whether the bird responds to the intrinsic characteristics of the crops or the landscape context in which crops are inserted. The proportion of forest species was higher in agroforestry crops (F28, 0,001 = 19.29, p <0.0004), while the proportion of generalists showed no significant difference (F28, 0,001 = 0.22, p <0.22) and species of open areas was greater in conventional crops (F28, 0,001 = 8.92, p <0.006). The two sets of variables considered, i.e. the internal structure of the crop and of surroundings, were important to predict the proportion of forest birds species. Although we observed the effect of landscape in the proportion of forest species, we note here that conventional systems, even in contexts similar to the landscape agroforestry systems, did not show the same proportion of forest species. This result indicates a upper value of agroforestry crops for the occurrence of forest bird species. At landscape level, the proportion of forests and consequently the lower isolation between patches is responsible for the potential presence of species in fragments. However, at patch level, even it is presenting a landscape context favorable to be occupied by a species of source areas, the mechanism that influences the presence of the species is the high internal structure of the banana plantations.
244

Agroecologia quilombola ou quilombo agroecológico? Dilemas agroflorestais e territorialização no Vale do Ribeira/SP / Agroecology quilombo or quilombo agroecological? Agroforestry Dilemmas and territorialization in the Vale do Ribeira/SP

Laura De Biase 15 July 2016 (has links)
A pesquisa apresentada nesta tese tem como objetivo realizar uma análise e reflexão sobre as estratégias metodológicas da agroecologia, com o intuito de compreender a forma pela qual lógicas econômicas não capitalistas (camponesa, quilombola e/ou indígena) têm participado e/ou poderiam participar do processo de construção- concepção e execução- deste campo do conhecimento. Numa busca por caminhos que indicassem as formas de equalizar as relações de poder inerentes ao diálogo de saberes e fazeres previsto na teoria agroecológica, optou-se por analisar a comunidade quilombola do bairro Ribeirão Grande -localizada no Vale do Ribeira, Barra do Turvo/SP - e suas experiências de produção agroflorestal e envolvimento com uma associação/cooperativa agroflorestal reconhecida nacional e internacionalmente, a Cooperafloresta. O recorte analítico neste território, portanto, compreende a investigação tanto sobre a comunidade quilombola, quanto sobre as estratégias metodológicas da Cooperafloresta. No decorrer da pesquisa identificou-se a existência de uma tensão entre o saber-fazer quilombola e o saber-fazer agroflorestal. Para compreender o processo de formação deste conflito e analisar as formas de relação estabelecidas no âmbito das experiências agroecológicas, realizou-se: uma análise biográfica da liderança quilombola Nilce de Pontes Pereira do Santos; um histórico e caracterização da comunidade do Ribeirão Grande desde o seu interior; e uma discussão sobre a forma pela qual a Cooperafloresta se constituiu naquele território. A intersecção entre estas três perspectivas de análise nos permitiu estabelecer cinco constatações, que se orientaram, de forma geral, para a identificação da contribuição da geografia à agroecologia . A conclusão desta pesquisa indicou a pertinência da orientação do método agroecológico à apreensão da totalidade da identidade local e da agroecologia enquanto contribuição ao movimento de comunidades rurais não capitalistas. / The research presented in this thesis aims to perform an analysis and reflect on the methodological strategies of agroecology, in order to understand the way in which non­ capitalist economic logic (peasant, Maroon and/or indigenous) have been and/or could be involved in the process - design and execution - of building this field of knowledge. Looking for paths that could indicate means to equalize the power relations inherent in the dialogue of knowledge and practices set out in agroecological theory, we chose to analyze the quilombo community of Ribeirão Grande neighborhood - located in the Vale do Ribeira, Barra do Turvo/SP- and their experience with agroforestry production and involvement with an agroforestry association/cooperative nationally and internationally recognized, Cooperafloresta. The analytical approach in this area therefore includes research on both the quilombo and the methodological strategies of Cooperafloresta. The existence of a tension between the quilombo and the agroforestry know-hows could be identified during the study. Research took place in order to understand the process of formation of this conflict and analyze the forms of relationship established under the agroecological experiences: a biographical analysis of quilombo leader Nilce de Pontes Pereira do Santos; a past history and characterization of Ribeirão Grande community from the inside; and a discussion about how Cooperafloresta has been constituted on that territory. The intersection of these three perspectives of analysis allowed us to establish tive findings, which guided, in general, to identifying the contribution of geography to agroecology. The conclusion of this research indicated the relevance of the guidance of agroecological method to the seizure of all the local identity and of agroecology as a contribution to the movement of rural non-capitalist communities.
245

Áreas prioritárias para serviços ecossistêmicos hidrológicos no Sistema Cantareira / Priority areas to hydrology ecosystem services in Cantareira System

Claudia Moster 18 July 2018 (has links)
A modelagem de serviços ecossistêmicos hidrológicos é uma ferramenta auxiliar na tomada de decisões para investimento financeiro em práticas de uso da terra e em projetos para a restauração florestal. Em virtude da necessidade de melhoria no provimento desses serviços ao menor custo de investimento para o Sistema Cantareira, este trabalho teve o objetivo de simular cenários para avaliação de atividades de transição do uso e cobertura da terra e identificação de áreas prioritáriass, considerando critérios ambientais, sociais e políticos. A região do estudo compreende um complexo hidráulico de transposição de bacias dos rios Piracicaba, Capivari e Jundiaí (PCJ) para a bacia do Alto Tietê, que possui a finalidade de abastecimento de água para a região metropolitana de São Paulo. Foram utilizados os modelos InVEST e RIOS, ferramentas compostas por métodos consagrados da literatura científica, como a equação universal da perda de solo e o balanço hídrico de massa em bacias. São modelos baseados na valoração do capital natural, utilizados para a avaliação da exportação de sedimentos e produção de escoamento base, de acordo com o valor de investimento e o custo de atividades, respectivamente. As atividades definidas para transição compreenderam a alteração das áreas agrícolas de pastagem para sistema agroflorestal (silvipastoril), a restauração florestal assistida e a regeneração natural. A diferença entre os cenários foi a adoção das atividades propostas e o montante de recursos a ser aplicado por sub-bacia. Os melhores cenários para redução na exportação de sedimentos foram avaliados em relação à transição na área total de drenagem e para a produção hídrica sazonal. O modelo RIOS demonstrou maior sensibilidade aos custos das atividades de transição e à efetividade no controle da erosão, sendo que, os critérios aplicados para áreas preferenciais demonstraram um bom resultado na priorização das áreas. No modelo InVEST foi possível identificar as sub-bacias que apresentaram maior exportação de sedimentos e os cenários com melhor resultado para a diminuição, identificados como plantio e regeneração. A regeneração demonstrou ser a atividade com melhor benefício, com redução de 33,20% e aumento de 24,10% no escoamento base, quando considerada a área preferencial de transição em APP, declividade até 25% e vertentes de face sul, para a distribuição de áreas pelo modelo. / The modeling of hydrological ecosystem services is an auxiliary tool in decision making for financial investment in land use practices and in forest restoration projects. Due to the need for improvement in the provision of these services at the lowest investment cost for the Cantareira System, this work aimed to simulate scenarios for the evaluation of land use and land cover transition activities and identification of priority areas, with environmental, social and political criteria. The study area comprises a hydraulic complex for the transposition of the Piracicaba, Capivari and Jundiaí (PCJ) river basins into the Alto Tietê basin, which has the purpose of supplying water to the metropolitan region of São Paulo. The InVEST and RIOS models, composed by scientific tools approaches as university soil loss equation and water mass balance in watersheds. They are based on the valuation of natural capital, used for the evaluation of sediment exports and production of base flow, according the investment value and cost of activities, respectively. The activities defined for transition included the change from pasture to agroforestry (agroforestry pasture), assisted forest restoration and natural regeneration. The difference between the scenarios was the adoption of the proposed activities and the amount of resources to be applied in each watershed. The best scenarios for the reduction of sediment exports were evaluated in relation to the transition in the total drainage area and for seasonal water production. The RIOS model showed greater sensitivity to the costs of transition activities and erosion control effectiveness, and the criteria applied to preferential areas showed a good result in the prioritization of the areas. In the InVEST model, it was possible to identify the watersheds that had the highest export of sediments and the scenarios with the best result for the decrease, identified as planting and regeneration. Regeneration was the most favored activity, with a reduction of 33.20% and 24.10% of increase in the base flow, when considering the transition in APP, the slope by 25% and south face slopes as choose criteria to model distribution areas.
246

Análise emergética de um sistema agroflorestal = Sítio Catavento, Indaiatuba, SP / Emergy analysis of an agroforestry system

Albuquerque, Teldes Correa 19 August 2018 (has links)
Orientador: Enrique Ortega Rodriguez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T18:54:34Z (GMT). No. of bitstreams: 1 Albuquerque_TeldesCorrea_D.pdf: 7267454 bytes, checksum: 6b7d1a0c37b6579116030821ad560cea (MD5) Previous issue date: 2012 / Resumo: A forma de produção da agricultura em larga escala, intensiva em defensivos agrícolas, tem demonstrado ser destrutiva quanto à preservação da biodiversidade e de outros fatores de produção como solo e água. Neste sentido, novas alternativas de produção agrícola têm sido estudadas e aplicadas objetivando a recuperação dos solos, entre as quais se destaca a metodologia de sistemas agroflorestais (SAFs). A presente pesquisa tem como objetivo estudar o processo de recuperação de uma área degradada por meio da implantação de um sistema agroflorestal no Sítio Catavento, localizado no município de Indaiatuba, São Paulo, para evidenciar a viabilidade econômica dos SAFs para pequenos produtores rurais, assim como mostrar a eficiência dessa técnica na recuperação de solo degradado. Foram utilizadas neste trabalho as seguintes ferramentas científicas: (a) metodologia emergética proposta por Howard T. Odum, (b) metodologia de consórcio de espécies com sucessão vegetal e ciclagem de nutrientes desenvolvida por Ernst Götsch. Foram feitos: o levantamento dos dados sobre cobertura do solo, espécies vegetais existentes e a classificação das mesmas, bem como a identificação de suas funções ecológicas e econômicas e seus ciclos de vida. Foi equacionado e calculado o crescimento de cada uma das espécies do sistema agroflorestal. Foi estimado o valor da percolação de água de chuva. Foram obtidos os indicadores emergéticos para um ciclo completo de recuperação florestal (cinquenta anos). Os índices emergéticos calculados foram: Transformidade (Tr), Renovabilidade (%R), Razão de Rendimento Emergético (EYR), Razão de Investimento de Emergia (EIR) e a Razão de Intercâmbio de Emergia (EER). Foram encontrados os seguintes valores: a Transformidade se mantém entre 8000 e 12000, o valor inicial de EYR é 2 e depois cresce (6,5 no ano 10 e 13 no ano 50), EIR inicia com 0,17 e chega aos 40 anos com o valor de 0,10 pois o investimento é mínimo, EER inicia com 1,0 e depois decresce rapidamente (0,2 no ano 4) e a seguir decresce lentamente com o valor mínimo de 0,1 no ano 40 e depois se recupera um pouco (chegando a 0,2 no ano 50) e a Renovabilidade inicia em 52% e chega a 81% no terceiro ano, depois cresce lentamente até atingir 93% no ano 50. O lucro anual foi calculado para o caso da agricultura patronal e da agricultura familar considerando uma área de 1 ha. A patronal tem rentabilidade negativa nos primeiros 4anos, a partir do ano 5 o lucro é US$ 550 / ha.ano, no ano 6 é 900 US$ ha.ano e no ano 40 chega a US$ 17000/ ha.ano. Para o agricultor familiar os resultados são melhores / Abstract: The large-scale agricultural production system with intensive use of pesticides has been questioned by not preserving the biodiversity, the soil and the water. In this sense, new alternatives for agricultural production have been studied and implemented aiming at recovering the soil through farming techniques, among which stands out the agroforestry systems (AFS). This research aims to study the recovery of a degraded area through the establishment of an agroforestry system in Catavento farm, located at Indaiatuba county, São Paulo, in order to demonstrate either the economic viability of agroforestry systems for small farmers and the high ecological efficiency of this agricultural practice for recovering degraded environments. The method used in this study is based in: (a) ecosystems assessment using emergy methodology, as proposed by H. T. Odum (1996); (b) species consortium with vegetable succession and nutrients cycling, methodology developed by Ernst Götsch. A data survey has been done on soil covering, existing species and their classifications, as well as the identification of their ecological and economic functions and their life cycles. By applying the mentioned methodologies, a prediction of the agroforestry system behavior and a diagnosis of the dynamic process of ecological restoration have been done, using emergy indicators calculated for one complete cycle of forest recovery (fifty years). The emergy indices obtained were: Transformity (Tr), Renewability (% R), Emergy Yield Ratio (EYR), Emergy Investment Ratio (EIR) and Emergy Exchange Ratio (EER). There were found the following indices: Transformity remains between 8000 and 12000; the initial value of EYR is 2 and then it grows to 6.5, in year 10 and to 13, in year 50; the value of EIR starts at 0.17 and, after 40 years it decreases to 0.10 because the investment is minimum; the value of EER (1.0) at first decreases rapidly (0.2 in year 4) and then decreases slowly (minimum value of 0.1 in 40 years) and then it shows a slight recovery (up to 0.2 years in 50), Renewability starts at 52% and reaches 81% in the third year, then grows slowly up to 93% in 50 years. The annual profit has been calculated for the cases of employer and familiar agricultures. In the employeremployee case, the profitability is negative in the first 4 years; in the year 5, the profit is $550/ha.year, goes to US $ 900/ha in year 6 and reaches a maximum in year 40 (US$ 17.000). For the family managed farm without employees, results are better. The Catavento SAF results are promising and show, besides the recovery of biodiversity, greater valuation of rural activity, with improved socioeconomic conditions for families of small farmers / Doutorado / Engenharia de Alimentos / Doutor em Engenharia de Alimentos
247

Environmentally friendly agriculture in Tanzania : A case study of a farm in Himiti village, Babati

Karlsson, Marie January 2016 (has links)
Total agriculture area has during the last decades been reduced because of urbanization, land deterioration, and inputs of chemicals. Today many farmers produce monocultures and the agricultural production system has been reaching far away from a natural system. Attention is now needed to establish and minimize environmental impacts through changes towards a more environmentally friendly agriculture, worldwide. The aim of this thesis has been to examine an agroforestry system in Babati to see if and how this agricultural system is a sustainable agricultural production system. Through the theoretical framework of this thesis the agroforestry system is compared to what current research frontier present as needed for a more environmentally friendly agriculture, with the main importance to obtain fertile soils.The case study were made through semi-structural interviews and observation between February and March 2016 and showed that the agroforestry system examined met many of the needs presented for a sustainable agriculture, through no tillage, low-input of pesticides and no fertilizers, and by having a diverse system with crops and trees supporting healthy soils.
248

The tropical mixed garden in Costa Rica : a potential focus for agroforestry research?

Price, Norman William 05 1900 (has links)
Overpopulation and over-exploitation of resources continues to strain the process of development for many countries in the tropics. In Latin America deforestation and the subsequent marginalization of these lands has put pressure on the agricultural research community to develop appropriate land-use systems for these areas. Agroforestry is one class of such systems that are presently receiving much attention. The tropical mixed garden, in particular, is one such system that has attracted attention from researchers in various countries. The present study has focused upon the traditional mixed garden system, as found in Costa Rica, with the objective of determining its potential for increased contribution to small farming systems. Development of the data base for this assessment included a survey of 225 farms distributed throughout Costa Rica, year-long case studies of six farms, divided between two contrasting ecological zones, and a simple simulation model of a mixed garden agroforestry system. The mixed garden is clearly an important component of small farming systems in Costa Rica. Though half of the gardens studied were only between 0.01 to 0.20 hectares in size, half were greater, and a few encompassed a hectare or more of land. As a percent of total farm size, mixed gardens were most important in the Tropical Dry Forest and Tropical Moist Forest life zones. Mixed gardens are more common in economically depressed areas and less so in areas where farmers are well off. The ranking of various factors representing ecological complexity of mixed gardens is what one would expect if difference in garden complexity were determined solely by between-zone differences in the environment, thus supporting hypothesis 1. On the other hand, multivariate analysis of species presence/absence data for mixed gardens suggest that the hypothesis (Hypothesis 2) that Holdridge's system of ecological classification is an adequate means of stratifying the variation in species composition in mixed gardens is false. The findings also support the hypothesis (Hypothesis 3) that the mixed garden has a higher energy benefit-cost ratio than commercial cropping systems. The commercial cropping systems on the farms studied consumed between 9 to 10,000 times the amount of cultural energy as did the mixed gardens. Mixed gardens on small farms have the potential to contribute much more to the cash economy of the farm household than they generally do at present. The observations reported here concerning labour patterns and management practices, together with the economic analysis, support the hypothesis (Hypothesis 4) that the output of the mixed garden can be improved. The economic and labour use analysis presented here also supports the hypothesis (Hypothesis 5) that "the mixed garden exists as a supplementary enterprise whose primary function is to absorb excess farm labour." With due regard for the limitations of a simulation of the type used in this thesis, I find support for the contention that the traditional mixed garden in Costa Rica can be developed into an ecologically conservative yet commercially viable cropping system. In particular, the incorporation of high-value timber species shows the potential to significantly improve the long-term economy of the farm. Integrating animal production, as Wagner (1957) had advocated earlier, also can enhance garden productivity. / Graduate and Postdoctoral Studies / Graduate
249

Mathematical Programming Applications in Agroforestry Planning

Reeves, Laurence H. 01 May 1991 (has links)
Agroforestry as a sustainable production system has been recognized as a land use system with the potential to slow encroachment of agriculture onto forested lands in developing countries. However, the acceptance of nontraditional agroforestry systems has been hampered in some areas due to the risk-averse nature of rural agriculturalists. By explicitly recognizing risk in agroforestry planning, a wider acceptance of agroforestry is possible. This thesis consists of a collection of three papers that explore the potential of modern stock portfolio theory to reduce financial risk in agroforestry planning. The first paper presents a theoretical framework that incorporates modern stock portfolio theory through mathematical programming. This framework allows for the explicit recognition of financial risk by using a knowledge of past net revenue trends and fluctuations for various cropping systems, with the assumption that past trend behavior is indicative of future behavior. The paper demonstrates how financial risk can be reduced by selecting cropping systems with stable and/or negatively correlated net revenues, thereby reducing the variance of future net revenues. Agroforestry systems generally entail growing simultaneously some combination of plant and/or animal species. As a result, interactions between crops usually cause crop yields within systems to deviate from what would be observed under monocultural conditions, thus requiring some means of incorporating these interactions into mathematical models. The second paper presents two approaches to modeling such interactions, depending on the nature of the interaction. The continuous system approach is appropriate under conditions where yield interactions are linear between crops and allows for a continuous range of crop mixtures. The discrete system approach should be used where nonlinear interactions occur. Under this second approach, decision variables are defined as fixed crop mixtures with known yields. In the third paper, the techniques presented above were applied to a case study site in Costa Rica. Using MOTAD programming and a discrete system approach, a set of minimum-risk farm plans were derived for a hypothetical farm. For the region studied, results indicate that reductions in risk require substantial reductions in expected net revenue.
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Agroforestry in the Temperate Landscape: Precedent, Practice, and Design Proposal

Darr, Alexander Norton 20 September 2019 (has links)
Temperate agroforestry systems are an important area of research and practice in Eastern North America with the goal of creating more diverse, productive, and environmentally sound agricultural landscapes by using trees as key crops. There is extensive published research on contemporary temperate agroforestry models as well as tropical indigenous agroforestry systems, but publicly accessible properties that demonstrate these practices are currently limited. These practices, which include: Alley Cropping, Multi-functional Riparian Buffers, Short-rotation coppice, Non-timber forest farming, and novel crop breeding have potential to radically reshape American agricultural practices. As sediment and erosion control becomes stricter in agricultural land, and if future carbon tax or pricing legislation comes into play, non-tillage based agricultural practices will become more prevalent throughout the United States and the rest of the world. In the Mid-Atlantic region of the United States, where this project is based, orchards are a common perennial cropping system, but at present the industry is reliant on chemical inputs that have an economic and ecological cost associated with them. Developing, demonstrating, and popularizing systems that incorporate native, crop-bearing perennials, in a manner that is legible, aesthetically pleasing, and well-integrated into the surrounding topography and agricultural vernacular, this thesis will offer a proof-of-concept to landowners curious about incorporating low-input agroforestry practices. This thesis presents a series of unpublished manuscripts based on research of historical agroforestry practices in temperate North America. These manuscripts focus on agroforestry practices as they were practiced over nearly 500 years of American history. These findings culminate in the proposition of a design for an agroforestry research and demonstration farm in the Mid-Atlantic United States. The goal of this design is to recontextualize a historic dairy farm in Maryland, USA with the construction of a new education, production, and design center. This center, along with its associated infrastructure, the cropping layout, and an interpretive trail through a range of agroforestry systems proposes an immersive environment that allows a visitor to experience agroforestry at its many scales, from garden to wild-land. / Master of Landscape Architecture / Temperate agroforestry systems are an important area of research and practice in Eastern North America with the goal of creating more diverse, productive, and environmentally sound agricultural landscapes by using trees as key crops. There is extensive published research on contemporary temperate agroforestry models as well as tropical indigenous agroforestry systems, but publicly accessible properties that demonstrate these practices are currently limited. These practices, which include: Alley Cropping, Multi-functional Riparian Buffers, Short-rotation coppice, Non-timber forest farming, and novel crop breeding have potential to radically reshape American agricultural practices. As sediment and erosion control becomes stricter in agricultural land, and if future carbon tax or pricing legislation comes into play, non-tillage based agricultural practices will become more prevalent throughout the United States and the rest of the world. In the Mid-Atlantic region of the United States, where this project is based, orchards are a common perennial cropping system, but at present the industry is reliant on chemical inputs that have an economic and ecological cost associated with them. Developing, demonstrating, and popularizing systems that incorporate native, crop-bearing perennials, in a manner that is legible, aesthetically pleasing, and well-integrated into the surrounding topography and agricultural vernacular, this thesis offers a masterplan to create a proof-of-concept demonstration site to landowners curious about incorporating low-input agroforestry practices. This thesis presents a series of unpublished manuscripts based on research of historical agroforestry practices in temperate North America. These manuscripts focus on agroforestry practices as they were practiced over nearly 500 years of American history. These findings culminate in the proposition of a design for an agroforestry research and demonstration farm in the Mid-Atlantic United States. The goal of this design is to recontextualize a historic dairy farm in Maryland, USA with the construction of a new education, production, and design center. This center, along with its associated infrastructure, the cropping layout, and an interpretive trail through a range of agroforestry systems proposes an immersive environment that allows a visitor to experience agroforestry at its many scales, from garden to cultivated wilds.

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