Agricultural land use near streams frequently results in long-term disturbance to woody riparian vegetation and an alteration of reach scale geomorphic structure. Such disturbances often result in increased fine sediment input to the stream along with direct changes in channel structure. The study described here was designed to quantify stream geomorphic changes associated with agriculture and their influence on reach scale transient storage hydraulics and sediment biological function. Six small streams in the Appalachian Mountains of western North Carolina were selected to compare 3 reaches with active near-stream agriculture to 3 forested reference reaches. The study site categories differed significantly in many structural and hydraulic properties including slope, sinuosity, sediment size, and transient storage extent. However, differences cannot be attributed to land use alone. Distinct disparity in slope suggests that many of the categorical differences between stream types may also reflect valley scale structure. Despite these larger scale controls, the abundance of suspendable fines varied substantially among agricultural stream substrates, possibly due to varied land-use practices. Suspendable fine sediments and valley slope explained 91 % of variability in transient storage exchange, and abundance of inorganic fine sediments explained 77 % of variability in sediment microcosm nitrate production. This study supports conclusions that reach-scale influence of fine sediments occurred within the context of larger-scale valley structure, with implications on stream hydraulics and biogeochemistry. / Master of Science

No Abstract Provided / Thesis / Bachelor of Arts (BA)

In this work it is address the question of how certain climatic variables may be significant related to alterations of avian biodiversity in a semi-agricultural Natura wetland side in Northern Greece. Particularly, the current research highlights the effects of climate and land cover intensity on the Thermaikos gulf bird biodiversity and its importance for healthy ecosystem functioning. Also, the maintenance of a good state of conservation in the Thermaikos gulf has direct impacts on a larger scale since it benefits the rest of the Natura wetlands network considering the connectivity related to migratory birds. Furthermore, the methodology which is used is essential to help inform the science-based management of environments that support threatened and endangered wildlife and can be further applied to other wetlands in the Mediterranean with similar weather conditions and agricultural land use. The alteration in compositional diversity of bird abundances has been studied at the species level from 2012 to 2017 in one of the most important wetland Natura sites in Northern Greece and by using different biodiversity indices. Shannon Entropy was lower during 2012 (DH = 1.509) albeit remained in similar levels from 2013 and afterwards. The highest values of Shannon Entropy were recorded in 2014 (DH = 2.927) and 2016 (DH = 2.888) suggesting that there is a higher diversity compared to the other observation years and especially 2012. The yearly trends of the Simpson dominance index and the Gini-Simpson Index had quite similar patterns. The Berger-Parker index, DD, which represents the maximum proportion of any species estimated in the sample assemblage, had its highest values in 2012 (DD = 0.58) and 2017 (DD = 0.39) and its lowest in 2014 (DD = 0.13) and 2016 (DD = 0.15). A complete characterization of diversity was possible through the projection of Hill numbers and the Rényi entropy, parameterized by the order q in terms of an empirical curve. According to the Hills numbers pooled over the years, the mean species abundance (q = 0) was estimated at 31 species, the mean biodiversity (q = 1) was 13 species and the most dominant species (q = 2) were 8 species. The quantification of bird biodiversity in the particular research area patterns is a fundamental task to evaluate current management actions, improve conservation and design future management strategies. Moreover, the interplay between temperature, relative humidity and three different bird biodiversity indexes, including Shannon Entropy, Simpson’s dominance (evenness) index and the Berger-Parker index has been also examined. By using different modeling approaches, parametric and non- parametric multivariate models, we make effort to get a consensus on the interrelationships between climate and avian biodiversity. In particular, it is been shown that in most cases nonlinear models and surface-plot analysis methodology, are able to capture the relation of a considerable increase in the estimated biodiversity indexes with increased temperatures and rain levels. Thus, biodiversity is to a significant extent affected by the aforementioned climate factors at a proximate level involving synergies between the different climate factors. Finally, the combined effect of climate variables and remote sensing land cover indicators on bird richness has been also explored to detect any influence on bird diversity due to agricultural intensification. In particular the association between bird richness and environmental drivers, as well as remote sensed land cover indices was explored for seven successive seasons using correlation analysis and a Cox-Box transformed multivariate linear model. Three climate variables were tested: mean temperature, rain level and mean relative humidity and three land cover indices: the Normalized Difference Vegetation Index (NDVI), the Atmospheric Resistance Vegetation Index (ARVI) and an Agricultural Band Combination Index (ABCI). Among the environmental drivers explored, temperature, rain levels and ABCI were significantly correlated to bird richness in contrast to NDVI and ARVI which showed a lower correlation, while relative humidity displayed the poorest correlation. Additionally, the multivariable linear model indicates that temperature, rain levels and ABCI have a statistically significant effect (p<0.05) on bird species richness accounting for 73,02% of data variability. Based on the overall model results and the related 3D contour plot model simulations, we conclude that bird species richness increases with an increase in temperature and rain levels, as well as with a decrease in agricultural intensity (ABCI). Concluding, in most cases temperature, rain levels and agricultural intensity significantly influenced bird richness in a combined manner. Furthermore, agricultural intensification has resulted in most cases in the loss of bird richness. Understanding the factors that can affect the biodiversity is of great importance for rational land use planning and conservation management of semi-Natural areas. Agriculture is the main driving force that influences the topographic and biological diversity of Europe, shaping the natural landscape of the European countryside for thousands of years. Revealing potential interrelationship between biodiversity, climate drivers and landscape indicators, although is a complex—even though challenging—task, contributing to our understanding of the mechanisms connecting climate change with ecosystem functioning. Moreover, a better understanding of biodiversity functioning in relation to human activities in natural protected areas as well as climate is essential for biodiversity awareness and the design of effective biodiversity-related conservation management policies.

Many factors influence agricultural land, in particular, climate change show the most significant and serious effect on agricultural land in Phong Dien district. This study applied Binary Logistic analysis, using the SPSS software, on data collected through state agencies, fieldwork and interviews. The study has identified the impact of climate change on agricultural land by several factors; the most significant influence is derived from temperature and other extreme weather factors. In addition, the elements of rainfall, wind, and cold air also have a substantial impact on agricultural land causing serious consequences such as damage, loss of construction quality, overload of water supply and drainage systems, landslides, damage to infrastructure systems, etc. Some adaptive solutions to counteract the effects of climate change on agricultural land include changing crop structure, upgrading facilities, raising awareness of officials, and peo-ple about climate change. / Công tác sử dụng đất nông nghiệp chịu ảnh hưởng từ rất nhiều yếu tố. Trong đó, yếu tố tác động của biến đổi khí hậu gây ảnh hưởng lớn và nghiêm trọng nhất đối với việc sử dụng đất nông nghiệp nói chung và trên địa bàn huyện Phong Điền nói riêng. Nghiên cứu đã sử dụng phân tích Binary Logistic trên phần mềm SPSS từ các số liệu thu thập được qua các cơ quan nhà nước, thực địa, phỏng vấn. Từ đó, nghiên cứu đã xác định được tác động của biến đổi khí hậu đến sử dụng đất nông nghiệp thông qua các yếu tố: Gây ảnh hưởng lớn nhất là yếu tố nhiệt độ và yếu tố cực đoan khác; ngoài ra, các yếu tố lượng mưa, chế độ gió và không khí lạnh cũng tác động không nhở vào việc sử dụng đất nông nghiệp . Các yếu tố này gây ra các hậu quả nghiêm trọng như làm hư hại, giảm chất lượng công trình, làm quá tải hệ thống cấp thoát nước, làm sạt lở, hư hại hệ thống cơ sở hạ tầng… Nghiên cứu đã đề xuất được một số giải pháp thích ứng của biến đổi khí hậu đến việc sử dụng đất nông nghiệp như thay đổi cơ cấu cây trồng, nâng cấp cơ sở vật chất, nâng cao nhận thức của cán bộ và người dân về biến đổi khí hậu.

How do indigenous people perceive and practice eco-agriculture, especially when it was introduced as a development project? This thesis aims to delve into this question by focusing on a policy-induced agrarian transition for Pumi community in Sino-Myanmar borderlands. Using ethnographic methods, I intend to offer an intimate account of a provincial programme to facilitate eco-agriculture in this ethnic region. With the conceptual framework presented, the current research starts with the introduction of Pumi agricultural history and indigenous farming knowledge, with a focus on Pumi biocultural heritage. Then, I will examine how the process of ‘indigenisation of modernity’ (Sahlins 2000) has occurred against the backdrop of Pumi eco-agriculture programme. The insights will be distilled from three different aspects, which are agricultural land use, technical practices, and governance issues. For each aspect, I will scrutinise to what degree the government is following an industrial model to design the eco-agriculture agenda which corresponds to the ‘conventionalisation hypothesis’ of organic production (Buck 1997) and is thus in alignment with their long-term strategic goals to ‘modernise’ this borderland region through agricultural transformations, whereas the local Pumi farmers are actively coping with the government’s external interventions, meanwhile searching for the ‘alternative pathway’ towards agricultural modernisation. In the final chapter, I will interpret the motives of the both actors in the programme. For the government, the post-development theory will be employed to provide a critique of the ‘development discourse’ embedded in the agenda. For local farmers, the concept of ‘environmentality’ (Agrawal 2005) will be focused to interpret the Pumi farmers’ motives to indigenise, which ultimately questioning the transforming powers of modernity and globalisation on Pumi agrarian society. Basically, this thesis aims to trace the socio-political processes which drive the ‘agrarian transition’ in a Southeast Asian frontier, and further demonstrate how the resource abundance in the borderlands can underpin intense processes of commodification and dispossession (Nevins and Peluso 2008; Ishikawa 2010; see also Milne and Mahanty, 2015), the implications of which crystallised in an ethnographic context. To a larger extent, this research aims to shed lights on the interactions between social structure and individual agency ― although the Pumi farmers are struggling to survive with the adaptation to modern inputs, they are still marginalised by the structured inequality of the market economy, which limited the farmers’ opportunities to improve their own livelihoods. Furthermore, this research also has significant policy implications as it addresses the issues such as agricultural policy and ethnic relations in the borderland regions. By reflecting upon the overlapping implications of highland livelihoods, agencies, and the transforming powers of social change, the current study aims to build a locally rooted understanding of Pumi eco-agriculture programme, and provide lessons for sustainable planning and future policy-making for rural development in developing countries such as China.

Sustainability is one of the biggest goals of humankind in the new millennium. An increasing global demand on agricultural products stimulates agricultural expansion in Brazil, especially in the Southwestern Amazon, namely in the Cerrado and Amazon biomes. A better understanding of biogeochemical cycles and their influence on natural and agricultural systems is key to achieve environmental sustainability and improve agricultural efficiency. These biogeochemical cycles are driven by microbes, and the aim of this thesis was to correlate microbial functional group abundances with differences in carbon, nitrogen, and greenhouse gas cycles in response to land use changes in Southwestern Amazon soils. This work was performed at the University of São Paulo, Brazil, and at the University of Massachusetts Amherst, USA, while the candidate was enrolled in Ph.D. programs at both universities. The thesis is composed of five studies. The first study shows that land use change from Cerrado and forest to agriculture (soybean, Glycine max (L. Merrill), in succession with other crops) or pasture (Brachiaria brizantha (Hochst. ex A. Rich.) did not reduce soil microbial diversity but changed microbial structure. The second study, a physicochemical background for this land use conversion, describes the alteration of C and N stocks, soil chemical parameters, and microbiological parameters such as biomass, biological C stocks, and changes in the abundance of prokaryotes and fungi. In the third and fourth studies microcosm experiments depict how the agricultural change to soybean and Brachiaria alter the original microbial structure found in forest or cerrado. These studies focused on abundances of key biogeochemical genes (amoA, nirK, nirS, norB, nosZ, mcrA, and pmoA) and correlated gene copy abundances with C, N, and GHG measurements. In the fifth study, in situ soil surveys and GHG samplings were used to characterize the changes from forest to pasture (B. brizantha, 25 years) or soybean crop system (for 2 years or 25 years in succession). We found correlations between genes and processes, indicating that gene abundances provide important microbial information for the understanding of the targeted biogeochemical cycles. Land use, rather than plant species, promotes alterations in microbial gene abundances and processes. During the survey period, forest exhibited higher microbial activity, resulting in higher nitrate availability and N2O emissions. These processes were correlated with higher abundances of process related genes. Nitrate and N2O emissions were lower in agricultural and pasture soils. CO2 emission was higher in the two-year-old soybean plot. The forest and two-year-old soybean plots acted as a sink for CH4, while the pasture plots represented a source of it. The results validated the use of gene abundance determination as a valuable tool to better understand C, N, and GHG processes. The genes nirK, nosZ, and 16S rRNA presented the best correlations with the processes. A larger temporal and spatial analysis is needed to infer statements on the processes dynamics due to land use change. For the first time gene abundance measurements were used to integrate the C, N and GHG cycles, giving insights into land use changes in Southwestern Amazon / Sustentabilidade é um dos maiores objetivos da humanidade no novo milênio. Uma demanda crescente por produtos agrícolas tem estimulado a expansão agrícola no Brasil, especialmente no Sudoeste da Amazônia, nos biomas Cerrado e Amazônia. Um melhor entendimento dos ciclos biogeoquímicos e suas influências em sistemas naturais e agrícolas é chave para se alcançar sustentabilidade ambiental e aumentar eficiência agrícola. Esses ciclos biogeoquímicos são guiados por microrganismos, e o objetivo dessa tese foi correlacionar abundância de grupos funcionais de microrganismos com carbono, nitrogênio e gases de efeito estufa (GEE) em resposta a mudança do uso da terra em solos do sudoeste da Amazônia. Esse trabalho foi realizado na Universidade de São Paulo e na Universidade de Massachusetts Amherst enquanto o doutorando esteve matriculado nas duas universidades. A tese é composta de cinco estudos. O primeiro estudo mostra que a mudança no uso da terra de Cerrado e floresta para agricultura (soja, Glycine max (L. Merrill), em sucessão com outros cultivos) ou pastagem (Brachiaria brizantha (Hochst. ex A. Rich.) não reduz diversidade microbiana, mas muda sua estrutura. O segundo estudo descreve as alterações nos estoques de C, N, parâmetros químicos e microbiológicos da conversão de Cerrado para agricultura e pastagem. No terceiro e no quarto estudos, microcosmos foram usados para avaliar a influência de soja e braquiária na microbiota dos solos. Genes chaves dos processos biogeoquímicos (amoA, nirK, nirS, norB, nosZ, mcrA, e pmoA) foram quantificados e correlacionados com C, N e GEE. No quinto estudo, coletas in situ de solo e gases foram usadss para caracterizar a mudança do uso da terra de floresta para pastagem (braquiária, 25 anos) e para agricultura (soja, segundo ano, e soja, 25 anos, em sucessão com outras culturas). Correlações entre genes e processos foram encontradas, indicando que abundância gênica fornece importantes informações para o entendimento dos ciclos biogeoquímicos. Mudança no uso da terra como um todo, mais do que a mudança de vegetação, promove as alterações na abundância gênica e processos do solo. Durante o período de coleta, floresta exibiu maior atividade microbiana, resultando em maior disponibilidade de nitrato e emissão de N2O. Esses processos correlacionam com maior abundância dos genes relacionados aos processos. Quantidades de nitrato e N2O foram menores em agricultura e pastagem. As emissões de CO2 foram maiores na área de soja de segundo ano. Os solos de floresta e soja de segundo ano se mostraram como drenos de metano, enquanto que a pastagem foi uma fonte de emissão. Os resultados validam o uso de abundância gênica como uma técnica valiosa para um melhor entendimento dos ciclos do C, N e GEE. Os genes nirK, nosZ, e 16S rRNA apresentaram as melhores correlações com os processos. Uma análise temporal e espacial mais abrangente é necessária para generalizações sobre a dinâmica dos processos na região estudada. Pela primeira vez abundância gênica foi usada para integrar os ciclos do C, N e GEE, colaborando para um melhor entendimento dos processos relacionados à mudança no uso da terra no sudoeste da Amazônia

Sustainability is one of the biggest goals of humankind in the new millennium. An increasing global demand on agricultural products stimulates agricultural expansion in Brazil, especially in the Southwestern Amazon, namely in the Cerrado and Amazon biomes. A better understanding of biogeochemical cycles and their influence on natural and agricultural systems is key to achieve environmental sustainability and improve agricultural efficiency. These biogeochemical cycles are driven by microbes, and the aim of this thesis was to correlate microbial functional group abundances with differences in carbon, nitrogen, and greenhouse gas cycles in response to land use changes in Southwestern Amazon soils. This work was performed at the University of São Paulo, Brazil, and at the University of Massachusetts Amherst, USA, while the candidate was enrolled in Ph.D. programs at both universities. The thesis is composed of five studies. The first study shows that land use change from Cerrado and forest to agriculture (soybean, Glycine max (L. Merrill), in succession with other crops) or pasture (Brachiaria brizantha (Hochst. ex A. Rich.) did not reduce soil microbial diversity but changed microbial structure. The second study, a physicochemical background for this land use conversion, describes the alteration of C and N stocks, soil chemical parameters, and microbiological parameters such as biomass, biological C stocks, and changes in the abundance of prokaryotes and fungi. In the third and fourth studies microcosm experiments depict how the agricultural change to soybean and Brachiaria alter the original microbial structure found in forest or cerrado. These studies focused on abundances of key biogeochemical genes (amoA, nirK, nirS, norB, nosZ, mcrA, and pmoA) and correlated gene copy abundances with C, N, and GHG measurements. In the fifth study, in situ soil surveys and GHG samplings were used to characterize the changes from forest to pasture (B. brizantha, 25 years) or soybean crop system (for 2 years or 25 years in succession). We found correlations between genes and processes, indicating that gene abundances provide important microbial information for the understanding of the targeted biogeochemical cycles. Land use, rather than plant species, promotes alterations in microbial gene abundances and processes. During the survey period, forest exhibited higher microbial activity, resulting in higher nitrate availability and N2O emissions. These processes were correlated with higher abundances of process related genes. Nitrate and N2O emissions were lower in agricultural and pasture soils. CO2 emission was higher in the two-year-old soybean plot. The forest and two-year-old soybean plots acted as a sink for CH4, while the pasture plots represented a source of it. The results validated the use of gene abundance determination as a valuable tool to better understand C, N, and GHG processes. The genes nirK, nosZ, and 16S rRNA presented the best correlations with the processes. A larger temporal and spatial analysis is needed to infer statements on the processes dynamics due to land use change. For the first time gene abundance measurements were used to integrate the C, N and GHG cycles, giving insights into land use changes in Southwestern Amazon / Sustentabilidade é um dos maiores objetivos da humanidade no novo milênio. Uma demanda crescente por produtos agrícolas tem estimulado a expansão agrícola no Brasil, especialmente no Sudoeste da Amazônia, nos biomas Cerrado e Amazônia. Um melhor entendimento dos ciclos biogeoquímicos e suas influências em sistemas naturais e agrícolas é chave para se alcançar sustentabilidade ambiental e aumentar eficiência agrícola. Esses ciclos biogeoquímicos são guiados por microrganismos, e o objetivo dessa tese foi correlacionar abundância de grupos funcionais de microrganismos com carbono, nitrogênio e gases de efeito estufa (GEE) em resposta a mudança do uso da terra em solos do sudoeste da Amazônia. Esse trabalho foi realizado na Universidade de São Paulo e na Universidade de Massachusetts Amherst enquanto o doutorando esteve matriculado nas duas universidades. A tese é composta de cinco estudos. O primeiro estudo mostra que a mudança no uso da terra de Cerrado e floresta para agricultura (soja, Glycine max (L. Merrill), em sucessão com outros cultivos) ou pastagem (Brachiaria brizantha (Hochst. ex A. Rich.) não reduz diversidade microbiana, mas muda sua estrutura. O segundo estudo descreve as alterações nos estoques de C, N, parâmetros químicos e microbiológicos da conversão de Cerrado para agricultura e pastagem. No terceiro e no quarto estudos, microcosmos foram usados para avaliar a influência de soja e braquiária na microbiota dos solos. Genes chaves dos processos biogeoquímicos (amoA, nirK, nirS, norB, nosZ, mcrA, e pmoA) foram quantificados e correlacionados com C, N e GEE. No quinto estudo, coletas in situ de solo e gases foram usadss para caracterizar a mudança do uso da terra de floresta para pastagem (braquiária, 25 anos) e para agricultura (soja, segundo ano, e soja, 25 anos, em sucessão com outras culturas). Correlações entre genes e processos foram encontradas, indicando que abundância gênica fornece importantes informações para o entendimento dos ciclos biogeoquímicos. Mudança no uso da terra como um todo, mais do que a mudança de vegetação, promove as alterações na abundância gênica e processos do solo. Durante o período de coleta, floresta exibiu maior atividade microbiana, resultando em maior disponibilidade de nitrato e emissão de N2O. Esses processos correlacionam com maior abundância dos genes relacionados aos processos. Quantidades de nitrato e N2O foram menores em agricultura e pastagem. As emissões de CO2 foram maiores na área de soja de segundo ano. Os solos de floresta e soja de segundo ano se mostraram como drenos de metano, enquanto que a pastagem foi uma fonte de emissão. Os resultados validam o uso de abundância gênica como uma técnica valiosa para um melhor entendimento dos ciclos do C, N e GEE. Os genes nirK, nosZ, e 16S rRNA apresentaram as melhores correlações com os processos. Uma análise temporal e espacial mais abrangente é necessária para generalizações sobre a dinâmica dos processos na região estudada. Pela primeira vez abundância gênica foi usada para integrar os ciclos do C, N e GEE, colaborando para um melhor entendimento dos processos relacionados à mudança no uso da terra no sudoeste da Amazônia

早期農業係臺灣社會經濟發展之基石，各相關農業政策皆以糧食增產為主要目標，後因後期臺灣經濟由農業為主漸漸轉向以工業為主，故在時代變遷下，過去多數文獻指出第一次農地改革強調以「所有權」為中心，成功達到農業生產增加目的，以及Arthur Young之名言「荒漠變花園」，認為「所有權」是激勵農民生產之誘因，在現今都市化擴張及工商業發展的社會背景下，是否仍為當前農地政策之主要思維？實有重新探討之必要。爰此，本研究為探討臺灣農地利用是否仍需存有「所有權」之迷思，嘗試釐清在時代變遷下，農民是否須擁有農地所有權才能激勵農民從事農地利用？或只要能保障農民之投入成本能於未來收益相符，即便是透過使用權方式承租農地亦能激勵農民從事利用？並期能透過財產權觀點分析現行農地利用政策，提供未來農地政策研擬修訂之重要參考依據。 基此，本研究首先整理過去相關文獻及政府統計資料，在此基礎上釐清過去涉及地權政策之農地改革變遷過程，以及臺灣農地利用現況問題，藉以建立後續分析架構。其次，針對宜蘭縣三星鄉農民進行問卷調查，以釐清農民在從事農作過程中，擁有農地所有權對農民之影響情形，並瞭解農民透過購買或承租方式擴大農場經營規模之考量為何。最後，為深入分析及探究問卷調查結果之背後影響因素，本研究再針對中央及地方政府機關行政人員進行訪談，據以進行綜合分析。透過此研究脈絡之探討，本研究獲得之重要發現與結論，茲分述如下。 一、本研究透過實證分析得知，農民擁有農地所有權雖會對農地利用有正面影響，但不必然會直接激勵農民從事農作，仍需視當時的社會制度下，何種行為能夠激勵農民達到行為目標（增加所得），即具有激勵效果。而農民擁有農地使用權，亦能提高從事農地利用意願、激勵努力從事農業生產及維護農地環境，惟因使用權具有期限，故相較於農民擁有農地所有權，在提高農地改良投資及對長期從事農作有幫助兩方面，較無法激勵農民。因此，本研究結論指出過去以所有權為中心之農地政策，因社會變遷結果，不必然須再以所有權為中心，亦能具有激勵農民從事農作生產之效果。 二、依據本研究分析及推論，第一次農地改革之成功，應不能僅歸於創設所有權，而是因為透過政策實施重新界定財產權範圍，並建置財產權之權利及義務關係，故使農民投入之成本與未來收益能相符，願意投入更多的勞力從事農作，進而激勵農民願意努力從事農業生產，而建立第一次農地改革成功基礎。以此觀點亦能說明，第二次農地改革後，即便農民擁有農地所有權，惟因從事農作收益不佳，農民投入之成本於未來並無法充分回收時，則會變相導致農民任其休耕、閒置、消極利用，或是觀望日後農地變更之增值。因此，所有權並非能直接激勵農民從事農地利用，即便農民係透過承租方式擴大農場經營規模，只要能保障農民投入成本能與未來獲得收益相符，皆可激勵農民努力從事農作。 三、經本研究調查發現，由於目前購買農地價格太高，且農民擁有農地所有權與使用權對農地利用激勵效果相似，因此在資金條件不足情況下，透過承租方式取得農地，可減輕農民在資金負擔方面的壓力，實為未來主要擴大農場經營規模之方式。而目前政府所推動之小地主大佃農政策，雖係以承租方式擴大農場經營規模，且施行迄今頗具績效，然其政策績效似有成長趨緩之趨勢，故本研究針對小地主大佃農政策績效成長趨緩之原因進行分析，發現主要因地主願意出租之農地多已經初步釋出、三七五減租政策之持續影響、農民健康保險資格影響農地整合活化、缺乏地緣關係難透過承租農地擴大農場經營規模及特殊農業經營傾向以購買農地擴大農場經營規模等五項原因，可能影響該政策績效有趨緩成長之勢。故本研究基於研究觀察及發現，據以研提五項政策修正建議，包括：1.由於農地多已初步釋出，故應開始從農地規模化轉而思考農地集中化，不再僅追求量的成長；2.透過農地管理中心整合目前委託經營、口頭租約、代耕之擴大農場經營規模方式，不僅以書面契約為必要條件；3.調整農民健康保險之資格條件，不必然以擁有或承租一定農地面積以上為審查必要條件；4.透過現有大佃農師徒學習或是參與學習方式，引領新農民獲得當地農村信任感，順利承租農地；5.獎勵地主及承租人雙方簽訂長期農地租賃契約，以刺激承租人規劃及思考更長期之農地利用等，可供作為政府機關未來進行相關政策修訂及調整之參考依據。

L’objectif principal de cette thèse est d’instruire l’organisation des successions culturales, à l’échelle de la France et sur un recul décennal, tant en terme de cinétiques localisées qu’en terme de dynamiques liées à des variables explicatives du milieu physique et socio-technico-économiques. Ce travail de « fouille de données » est appliqué en France métropolitaine, en utilisant les bases de données publiques disponibles. Notre étude couvre la période 1992-2003 où s’implémenta la réforme de 1992 de la Politique Agricole Commune européenne et l’agenda 2000 en France. A partir d’une fouille de données sur l’ensemble des points Terruti sur cette période, 2549 successions culturales de trois ans furent identifiées. Ensuite, 21 clusters de l’ensemble des 430 régions agricoles (RA) françaises, quatre systèmes de culture, 90 RA, parangons des 430 RA, et trois régions principales appartenant à cinq des 21 clusters, regroupant les cultures de céréales, oléagineux et protéagineux, ont été définis. Deux approches de cinétiques des successions ont été réalisées : Une étude envisageant les successions de culture qui suivent les retournements de prairies permanentes. Une recherche des dynamiques d’évolution de successions culturales en lien avec des conditions externes. Nous proposons une utilisation ultérieure des méthodes mobilisées qui ont montré leur capacité à cartographier les grandes tendances d’évolution en France et à identifier les principales variables explicatives de ces évolutions. Les apports de cette thèse contribuent à améliorer notre compréhension des processus qui organisent les successions culturales en France et construisent par ces pratiques agricoles très dynamiques des impacts forts sur le territoire agricole français / In the context of changing agricultural policy, the development of agricultural production systems, increasing concern for agricultural sustainability and shifts in agricultural land management practice-related land-use change, the main objective of this thesis was to mine crop sequence patterns (CSP) and the relationships between CSP and the biophysical and socio-technical-economic conditions in mainland France from historical census data (e.g. land-cover survey, agricultural censuses, population census). Our study period 1992-2003 covers the implementation period of the 1992 European Union Common Agricultural Policy reform and Agenda 2000 in France. Both the classical statistical and data mining technique were applied in alone or combined ways in this thesis. First, we proposed an innovative approach to representing CSP within a given area and period at a large regional scale in a stationary way. The 2549 3-year crop sequences (CSs) were first identified as major CSs within all 430 agricultural districts (ADs) in mainland France during this period. Next, 21 clusters of ADs , four types of cropping systems, 90 representative ADs and three principal planting zones of cereals, oilseeds, and protein crops belonging to five clusters identified previously were further defined. We then explored CSP in a dynamic way by investigating CSP after grassland-to-cropland conversion, the temporal variability of CSP, and the evolution of the relationships between CSP and the external conditions over the study period. We conclude that the approaches developed here permit the representation of CSP at the large regional scale in both stationary and dynamic ways using time series land-cover data denoting specific agricultural cover types. The findings of this thesis contribute to improving the understanding of the process and pattern of human land management practices by agriculture affecting the terrestrial biosphere

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