Local food networks are often defined as presenting a variety of alternative food production, consumption, and distribution practices to the conventional food system such as community-supported-agriculture, farmers markets, and community gardens. Local food initiatives are commonly proposed as a model for the future of sustainable agriculture, and in the region of Portland, Oregon the abundance of such alternative venues results from the area's natural surroundings and smart planning. The region is host to 39 farmers markets and Portland is often hailed as one of the country's most sustainable cities. This study examines the role of local food networks in preserving agricultural land uses and livelihoods in Washington County, Oregon, a rapidly growing county adjacent to the city of Portland. I focus on small-scale agricultural landscapes where the producer sells at farmers markets or through community supported agriculture (CSAs). I explore farmers' concerns about urbanization and farmland preservation, their relationship to urban markets, motives to become a farmer, engagement with the surrounding environment, and their difficulties participating in local food networks. In addition, I explore farmers market managers' insights into the development of local food networks and how they see their markets supporting small-scale farmers. In a survey of consumers I examine consumer motives to `buy local' and consumer concerns about farmland preservation. The research is qualitative and explores: 1) the processes shaping the development of local food networks; 2) how particular ideas and images of nature and the countryside inform both consumer desires to purchase from farmers selling locally and; 3) how those same images of nature and the countryside inform and motivate people to become farmers participating in local food networks. In so doing, I argue that the networks that sustain urban and rural systems are important in understanding the development of local food networks, and that the preservation of economically and culturally important agricultural lands in Washington County depends on a diversity of opinions and rural narratives in order to preserve small-scale sustainable farmlands close-in to cities. The conclusion is that local food sold through alternative venues can be used as a means to preserve and develop specific and manageable farm sites and agricultural land uses but the impact is limited. Large scale impacts on agricultural land uses and livelihoods will depend on planners and advocates agreeing on policies that encompass a diversity of opinions, land uses, and land managers, while understanding the array of networks beyond the city that sustain both urban and rural systems.

No description available.

Indiana University-Purdue University Indianapolis (IUPUI) / The transfer of nutrients from US Midwest croplands into surface waters causes eutrophication and a decline in water quality. Temporary retention of nutrient-rich runoff in constructed wetlands can help mitigate these negative impacts through physical entrapment and biological transformation of nitrogen (N) and phosphorus (P). However, with the expectation that wet-dry periods will be more frequent in the region, there is a need to better understand the mechanisms that control nutrient retention and release in US Midwest wetlands constructed on former croplands. In this study, soil cores (30 cm long, 20 cm diam) were collected from two constructed wetlands (4 and 8-yr old), and the surface (0-20 cm) and subsurface (40-60 cm) layers of a cropland where a constructed wetland will be constructed in the future. Soil cores were subjected to either a moist or a dry treatment for 5 weeks, and then flooded with stream water (water depth 6 cm). The flux of nutrients, N2O, cations, and variation in floodwater chemistry (pH and ORP) were monitored for another 5 week period. Porewater was tested during the final 3 weeks of the experiment. Nitrate (0.1-130 mg N m-2 d-1) and inorganic P (Pi) fluxes (0.09-2.9 mg P m-2 d-1) were significantly higher in the dry treatment cores. Regardless of site, the dry treatment also resulted in higher floodwater NO3- concentrations suggesting organic matter mineralization and mineral N build up during the drying phase. However, this initial NO3- release was rapidly denitrified as indicated by the sharp increase in N2O production during that period. In contrast to N, the release of Pi was significantly higher in cores from the cropland. Soil at these sites had higher water extractable Pi and total P. Contrary to the study hypothesis and the results of previous studies, Pi concentration in floodwater and porewater was not correlated with dissolved Fe suggesting that reductive dissolution was not the dominant process controlling P release in US Midwest mineral soils developed from calcareous glacial till. Rather, variation in Ca2+ concentration and its relationship with Pi suggest that dissolution of Ca-containing minerals may be more important and should be the focus of future studies examining the geochemistry of P in these constructed wetlands.

Résumé : En Amérique du Nord, la superficie des monocultures utilisatrices d’intrants tels que des fertilisants et des pesticides couvre aujourd’hui 85 % des surfaces agricoles et autant de pâturages ont disparus en 50 ans afin de répondre aux besoins de l’Homme. Ces changements d’usage des terres ont profondément transformé le paysage et altéré la biodiversité des agro-écosystèmes. Parmi les espèces d’oiseaux champêtres, les insectivores aériens tels l’Hirondelle bicolore, Tachycineta bicolor, ici étudiée, présentent un fort taux de déclin des effectifs, reflétant probablement une dégradation des agro-écosystèmes. Les mécanismes biologiques à l’origine de ce déclin sont encore méconnus ainsi que les patrons de dispersion chez les passereaux migrateurs. Le présent travail vise à étudier les effets environnementaux sur les traits individuels (survie et succès reproducteur) et la dispersion de reproduction (probabilité de disperser et taux d’occupation des sites de reproduction) chez l’Hirondelle bicolore. Pour ce faire, 2200 reproducteurs et 8000 oisillons ont été bagués entre 2004 et 2013 et suivis en reproduction pendant 10 ans sur une aire d’étude au Sud du Québec, laquelle est composée de 40 sites et couvre une mosaïque de paysages agricoles hétérogènes. Le développement d’un nouveau modèle de capture-marquage-recapture, flexible d’utilisation, a permis de réduire les biais d’estimation des probabilités de survie et de dispersion de l’espèce. Cette approche a permis de tester l’effet de plusieurs variables en lien avec la qualité de l’habitat, l’information publique et les caractéristiques individuelles sur la variabilité des paramètres de dispersion, de survie et de succès reproducteur au niveau individuel. Les milieux cultivés intensivement associés à la présence du Moineau domestique, Passer domesticus, un compétiteur pour les cavités de reproduction, diminuaient au maximum de 19 % la survie des mâles. Les femelles étaient quant à elles affectées par le coût de la reproduction, qui était d’autant plus grand en milieu intensif qu’il y avait une présence de moineaux et une disponibilité moindre en ressources alimentaires. Pour autant, la décision de disperser n’était pas affectée par les conditions environnementales que ce soit par la présence de compétiteurs ou la qualité du milieu, et ne dépassait pas les 4 % chez les mâles. Les femelles dispersant jusqu’à 14 fois plus s’appuyaient sur leur expérience personnelle pour décider de disperser. Un échec de reproduction augmentait jusqu’à 7 fois la probabilité de disperser et pour la première fois chez une espèce à courte durée de vie, nous avons montré que la probabilité de disperser était augmentée l’année suivant une première dispersion. Ces patrons de dispersion étaient stables dans le temps. La dispersion semblait donc être un processus coûteux, comparé à la fidélité au site, qui apparaissait comme un phénotype minoritaire dans la population. Elle répondait à des conditions défavorables de reproduction. Enfin, ce travail montre l’utilisation de l’information publique dans la décision de s’établir sur un site généralement fortement dense et productif en jeunes l’année précédente et ce, une fois que la décision de disperser est amorcée. La présence de moineaux et la forte proportion de cultures intensives dans un rayon proche participaient également à ll‘évitement des sites lors de l’établissement. D’après ces résultats, le milieu intensif contribuerait au déclin de l’Hirondelle bicolore. / Abstract : In North America, monoculture areas using high inputs of fertilizers and pesticides cover 85 % of agricultural lands, and as many pastures disappeared in the past 20 years to satisfy human food needs. These land-use changes have deeply transformed landscapes and altered the biodiversity of agro-ecosystems. Among farmland birds, aerial insectivores such as Tree Swallow, Tachycineta bicolor, studied here show a high rate of decline in their abundance, partly reflecting the degradation of agro-ecosystems where they breed. Biological mechanisms leading to the decline and dispersal patterns in migratory passerines are still poorly known. The present work quantifies the environmental effects on Tree Swallow individual traits (survival, reproductive success) and breeding dispersal (probability to disperse and occupation rates of breeding sites). Between 2004 and 2013, 2200 breeders and 8000 chicks were ringed and monitored during 10 breeding seasons on a study area composed of 40 sites and covering a mosaic of heterogeneous agricultural landscapes in southern Québec. The development of a new, flexible capture-mark-recapture model has reduced estimate bias of survival and dispersal probabilities of Tree Swallows. This approach allowed to assess the effect of several variables linked to habitat quality, public information and individual characteristics on dispersal, survival and reproductive success parameters of individuals. Within intensively cultivated landscapes associated to the presence of a nest site competitor, the House sparrow, Passer domesticus, male survival is up to 19 % lower. Females were affected by the cost of reproduction, especially in intensive landscapes where House sparrows and found and where food resources and nest site appear limited. Dispersal probability was not affected by environmental conditions either through the presence of House sparrows or habitat quality, and was restricted to 4 % in males. Females, which dispersed up to 14 times more than males, based their decision on their personal experience. Breeding failure increased up to 7 times the probability to disperse and for the first time in a short-lived species, I show that dispersal likelihood increased if the individual had dispersed in the previous year. These dispersal patterns were stable in time. Dispersal appeared as a costly process compared to site fidelity and was a minority phenotype in the population. It appeared an answer to unfavorable condition for reproduction. Finally, this work shows the use of public information (partners density, fledglings productivity the previous year) on the decision to settle on a site and this, after the dispersal decision had been initiated. The presence of House sparrows and the proportion of intensive areas near nest boxes were used as information to select a breeding site. Based on these findings, agricultural intensification likely plays a role in the decline of Tree swallow populations.

O estado atual do desmatamento de florestas primárias e o restabelecimento de florestas secundárias no Brasil variam de acordo com a região do país. Enquanto alguns domínios têm perdido grandes extensões de cobertura original, como a Floresta Amazônica e o Cerrado, outros têm registrado um aumento na área ocupada por florestas, como é o caso da Mata Atlântica no estado de São Paulo. O processo de regeneração de florestas secundárias tem sido registrado nos últimos 30 anos, devido ao abandono de pastagens e iniciativas de restauração florestal. Dessa forma, o objetivo principal deste estudo foi investigar se florestas secundárias regenerando em pastagens abandonadas diferem em relação à composição e diversidade de espécies florestais sob duas condições distintas de característica da paisagem: áreas com elevada proporção de cobertura florestal no entorno (>30%) e áreas com baixa proporção de cobertura florestal no entorno (<10%). Com base em imagens do ano de 1972, foram delimitadas as áreas ocupadas por remanescentes antigos de vegetação, com idade superior a quarenta anos. Após, o mapa de vegetação produzido com estas imagens foi sobreposto a um mapa de cobertura da terra de 2018, para identificar a expansão e a diminuição da vegetação. Com base nestes dois mapas, nós avaliamos as modificações na estrutura da paisagem, durante este período de 46 anos. Depois disso, nós selecionamos oito áreas, sendo quatro estruturalmente conectadas, com elevada proporção de cobertura florestal no entorno e quatro estruturalmente isoladas, com baixa cobertura florestal no entorno. Em cada área nós avaliamos a composição, riqueza de espécies, densidade, síndrome de dispersão, biomassa acima do solo, diversidade e equabilidade. Contrário ao que esperávamos, nossos resultados demonstraram que as plantas do estrato inferior em áreas com baixa cobertura florestal no entorno tiveram maior proporção de espécies dispersas por animais do que nas áreas com alta cobertura florestal no entorno, bem como também foram encontradas diferenças na composição de espécies da comunidade do estrato inferior. Nossas descobertas indicam que as condições estruturais da paisagem podem influenciar grupos funcionais da comunidade do estrato inferior na região das cuestas, tornando o contexto da paisagem um parâmetro essencial a ser considerado na conservação e restauração da biodiversidade, especialmente em paisagens com elevado grau de fragmentação. / The current state of deforestation of old-growth forests and the restablishmet of secondary forests in Brazil varies according to the region. While some biomes have lost many extensions of original cover, such as Amazon forest and Cerrado, others have registered an increasing in the area occupied by forests, as the case of the Atlantic forest in São Paulo state. The regeneration process of secondary forests has been registered for the last 30 years, due to the abandonment of pastures and initiatives of seedling plantings. Therefore, the main goal of this study was to investigate whether secondary forests regenerating in abandoned pastures differ in relation to the composition and diversity of forest species under two different landscape characteristics: connected areas, with high proportion of forest cover around (>30%) and isolated areas, with low proportion of forest cover around (<10%). Based on images of 1972, old-forest remnants were delimited. After, the vegetation map produced for 1972 was overlapped to a land cover map of 2018 to record the expansion and decrease of vegetation. Based on these two maps, we evaluated the modifications in the landscape structure, during the 46-years period. After that, we selected eight areas, being four structurally connected and four, structurally isolated. At each area we evaluated composition, species richness, diversity, equability, density, dispersal syndrome and aboveground biomass. Contrary to expectations, our results showed that regenerating plants in isolated areas have higher proportion of animal-dispersed seed species than connected areas. We also found differences in the plant composition of regenerating communities between connected and isolated areas. Our findings indicate that structural conditions of the landscape can influence functional groups of the regenerating plants in the cuestas region, making the landscape context an essential parameter to be considered in conservation and restoration plans, especially in highly fragmented landscapes.

Heutige Agrarlandschaften stehen in der Kritik sich in ausgeräumte und unspezifische Räume zu wandeln, in denen wenige Fruchtarten auf immer größeren Schlägen angebaut werden und ein fortwährender Rückgang von Offenlandarten und artenreichen Biotopen stattfindet. In der bisherigen Forschung wurden vor allem die Ursachen für eine Homogenisierung landwirtschaftlicher Fluren betrachtet. Die vorliegende Dissertation untersucht hingegen durch welche Mechanismen ein höheres Maß an Heterogenität in Agrarlandschaften entsteht, entsprechend der Forschungsfrage: Unter welchen Voraussetzungen und durch welche Prozesse bilden sich unterschiedliche physische Erscheinungsformen in der heutigen Agrarlandschaft in einer bestimmten Anordnung heraus, um eine Vielfalt an Nischen für typische Arten und Wiedererkennungspunkte für den menschlichen Betrachter zu bieten? Im theoretischen Teil der Dissertation wurden Wirkungszusammenhänge für strukturbildende Prozesse in Agrarlandschaften aus den Forschungsfeldern der Landschaftsökologie sowie den Planungs- und Sozialwissenschaften ermittelt. Anschließend verknüpfte die Autorin diese Grundlagen zu einem Untersuchungsdesign, um die Forschungsfrage systematisch untersuchen zu können. Im angewandten Teil der Arbeit wurden drei landwirtschaftliche Fluren (Arnsgrün und Colmnitz in Sachsen, Lugau in Brandenburg) hinsichtlich der Mannigfaltigkeit und Dynamik der vorgefundenen physischen Erscheinungsformen in mehrmaligen Begehungen analysiert. Weiterhin führte sie leitfadenbasierte Interviews mit den landnutzenden Akteuren der untersuchten Fluren. Diese dienten u.a. zur Entwicklung einer Typologie, nach welcher die landnutzenden Akteure vertiefend betrachtet werden konnten. Im Ergebnis der Dissertation konnten Ursachen offen gelegt werden, welche zu einem höheren Maß an Nutzungsheterogenität beitragen. Hierzu zählten unterschiedliche, räumlich benachbarte Nutzungsziele und Alterszustände der Vegetation. Heterogene Nutzungsintensitäten und vielfältig angebaute landwirtschaftliche Kulturen zeigten im räumlichen Nebeneinander ebenfalls strukturbildende Wirkung. Die in der Dissertation festgestellten Zusammenhänge legten jedoch offen, dass einer Diversifizierung der Nutzung allein nicht ausreicht, um Agrarlandschaften positiv zu verändern. Vielmehr muss die Bedeutung der landnutzenden Akteure in die Planung einbezogen werden. So ließen sich bestimmte Merkmale der Landnutzer bzw. Akteurstypen feststellen, die mit einer hervorgehobenen Bedeutung für die Entstehung von Lebensräumen wildlebender Arten sowie für die menschliche Orientierung einhergingen. Gleichwohl verdeutlichten die Ergebnisse der Untersuchung, dass in erster Linie das Zusammentreffen verschiedener Akteure die Unterschiedlichkeit von physischen Erscheinungsformen in Agrarlandschaften befördert. Auf Grundlage des erhobenen Datenmaterials leitete die Autorin darüber hinaus acht strukturbildende Prinzipien für die drei untersuchten Fluren ab.

Promouvoir le service de contrôle biologique des bio-agresseurs des cultures nécessite de comprendre le fonctionnement des populations d’ennemis naturels dans des mosaïques agricoles qui sont hétérogènes et dynamiques. Cette thèse porte sur l’étude des déterminants de l’abondance des carabes impliqués dans la régulation des adventices via la consommation de leurs graines. L’analyse des variations d’abondance des espèces à une échelle nationale nous a permis d’évaluer le rôle relatif des facteurs locaux et paysagers et de mettre en évidence le rôle important de la proportion de colza et de prairie dans le paysage sur l’abondance de carabes consommateurs de graines dans les parcelles cultivées. Le suivi expérimental de la composition des communautés de carabes ainsi que du statut nutritionnel et des mouvements de plusieurs espèces dans des dispositifs colza/blé et colza/bordure pérenne sur l’ensemble de la période d’activité des carabes nous a permis de mettre en évidence que (i) les carabes répondent l’hétérogénéité de cette mosaïque agricole (type de culture, qualité de l’habitat au sein d’un même type de culture), avec des réponses souvent spécifiques (ii) que le colza d’hiver joue un rôle important dans le fonctionnement des populations de carabes consommateurs de graines du fait de sa haute qualité d’habitat pour ces espèces, (iii) que la variation de la qualité d’habitat peut jouer sur le mouvement des carabes vers l’habitat adjacent et (iv) que la présence d’une bordure pérenne au voisinage d’une culture favorise le maintien et le fonctionnement de plusieurs espèces consommatrices de graines d’adventices dans la mosaïque agricole. / Promoting biological pest control in crops requires to understand the functioning of natural enemies in heterogeneous and dynamic agricultural mosaics. This thesis focuses on the study of the determinants that influence the abundance of ground beetles involved in the regulation of weeds via the consumption of their seeds. In an analysis of the variations of species abundance at a national scale we identified the respective role of local and landscape factors and showed that oilseed rape and grassland proportions in the landscape were key determinants of the abundance of carabid species in cultivated fields. We then studied carabid communities through combined measured of their abundance, nutritional status and between-habitat movements, during an entire cropping season, in pairs of habitats consisting in winter oilseed rape fields with either a crop (winter cereal fields) or a semi-natural habitat (grassy field margins) as adjacent habitat. We demonstrated that (i) ground beetles respond to the heterogeneity of arable mosaic (crop type, habitat quality within the same crop type), often with specific responses, (ii) winter oilseed rape plays an important role in the functioning of weed seed-eating carabid species due to its high habitat quality, (iii) variations in habitat quality can influence the movement of beetles to the adjacent habitat and (iv) the presence of a grassy field margin in the vicinity of a crop promotes the maintenance and functioning of several species in arable mosaics.

Heutige Agrarlandschaften stehen in der Kritik sich in ausgeräumte und unspezifische Räume zu wandeln, in denen wenige Fruchtarten auf immer größeren Schlägen angebaut werden und ein fortwährender Rückgang von Offenlandarten und artenreichen Biotopen stattfindet. In der bisherigen Forschung wurden vor allem die Ursachen für eine Homogenisierung landwirtschaftlicher Fluren betrachtet. Die vorliegende Dissertation untersucht hingegen durch welche Mechanismen ein höheres Maß an Heterogenität in Agrarlandschaften entsteht, entsprechend der Forschungsfrage: Unter welchen Voraussetzungen und durch welche Prozesse bilden sich unterschiedliche physische Erscheinungsformen in der heutigen Agrarlandschaft in einer bestimmten Anordnung heraus, um eine Vielfalt an Nischen für typische Arten und Wiedererkennungspunkte für den menschlichen Betrachter zu bieten? Im theoretischen Teil der Dissertation wurden Wirkungszusammenhänge für strukturbildende Prozesse in Agrarlandschaften aus den Forschungsfeldern der Landschaftsökologie sowie den Planungs- und Sozialwissenschaften ermittelt. Anschließend verknüpfte die Autorin diese Grundlagen zu einem Untersuchungsdesign, um die Forschungsfrage systematisch untersuchen zu können. Im angewandten Teil der Arbeit wurden drei landwirtschaftliche Fluren (Arnsgrün und Colmnitz in Sachsen, Lugau in Brandenburg) hinsichtlich der Mannigfaltigkeit und Dynamik der vorgefundenen physischen Erscheinungsformen in mehrmaligen Begehungen analysiert. Weiterhin führte sie leitfadenbasierte Interviews mit den landnutzenden Akteuren der untersuchten Fluren. Diese dienten u.a. zur Entwicklung einer Typologie, nach welcher die landnutzenden Akteure vertiefend betrachtet werden konnten. Im Ergebnis der Dissertation konnten Ursachen offen gelegt werden, welche zu einem höheren Maß an Nutzungsheterogenität beitragen. Hierzu zählten unterschiedliche, räumlich benachbarte Nutzungsziele und Alterszustände der Vegetation. Heterogene Nutzungsintensitäten und vielfältig angebaute landwirtschaftliche Kulturen zeigten im räumlichen Nebeneinander ebenfalls strukturbildende Wirkung. Die in der Dissertation festgestellten Zusammenhänge legten jedoch offen, dass einer Diversifizierung der Nutzung allein nicht ausreicht, um Agrarlandschaften positiv zu verändern. Vielmehr muss die Bedeutung der landnutzenden Akteure in die Planung einbezogen werden. So ließen sich bestimmte Merkmale der Landnutzer bzw. Akteurstypen feststellen, die mit einer hervorgehobenen Bedeutung für die Entstehung von Lebensräumen wildlebender Arten sowie für die menschliche Orientierung einhergingen. Gleichwohl verdeutlichten die Ergebnisse der Untersuchung, dass in erster Linie das Zusammentreffen verschiedener Akteure die Unterschiedlichkeit von physischen Erscheinungsformen in Agrarlandschaften befördert. Auf Grundlage des erhobenen Datenmaterials leitete die Autorin darüber hinaus acht strukturbildende Prinzipien für die drei untersuchten Fluren ab.

Landscape heterogeneity is thought to differ among farm management types (i.e. organic and conventional), and this difference is hypothesized to result in variations in pest control by natural enemies. However, it is unclear if these variations in pest control are driven by landscape structure or by farm management practices themselves. Remotely sensed datasets were used to describe the landscape structure surrounding a group of organic and conventional caneberry farms in Oregon and Washington that have different leafroller parasitism rates attributed to farm management type. A finer scale survey was done at one of the farms using the remotely sensed data as well as field surveys. Landscape metrics of diversity, richness and percent non-crop were used to describe the landscapes surrounding the farm fields at scales ranging from 0.05 km to 5.00 km for the large scale study, and 0.05 km to 0.20 km for the fine scale study. In the fine scale study, data on parasitoid species assemblages, diversity, and parasitism rate were collected and analyzed against the calculated landscape metrics spatially and seasonally. The purpose of this study was to quantify effects of farm management type on habitat structure, effect of habitat structure on leafroller parasitism rate, and to access correlations between landscape metrics calculated at the landscape and field scale. Overall, the farms were embedded in a landscape that was broadly similar, with very few differences in landscape structure occurring between organic and conventional farms. Organic farms had higher vegetation height class diversity at the largest scale compared to conventional farms, while conventional farms had significantly higher percent non-crop area compared to organic farms. There was no significant effect of any of the calculated landscape metrics on parasitism rates. In the field scale study, no correlations were found between habitat metrics and parasitism rates, or between field based metrics and those calculated at the landscape scale. The results of this study suggest that conventional and organic caneberry farms in the Willamette Valley are broadly similar in the habitat conditions they provide parasitoids. This suggests that management changes to pesticide use alone could increase levels of leafroller biological control on conventional farms to levels that are comparable to those seen on organic farms. Our comparisons of the landscape scale and field scale landscape metrics showed no connection, this suggests that direct comparisons cannot be made with these particular metrics at these very different scales. Rather than comparing these types of data, it may be more useful to combine them in order to increase the resolution and predictive power of remotely sensed data for describing landscapes at broad scales. / Graduation date: 2013

Comprendre comment la biodiversité des prairies répond aux changements d’utilisation des terres constitue un enjeu majeur pour la conservation de la biodiversité et le maintien des services écosystémiques dans les paysages agricoles. Dans ce travail de thèse, nous avons cherché (i) à analyser la réponse simultanée d’un ensemble de taxons appartenant à différents niveaux trophiques (plantes, herbivores, pollinisateurs, prédateurs) aux changements d’utilisation des terres agissant à différentes échelles spatiales et temporelles ; (ii) à approcher les mécanismes impliqués dans cette réponse et notamment le rôle des interactions trophiques. Notre approche est basée sur l’utilisation de multiples traits fonctionnels liés à l’acquisition des ressources, la taille et la mobilité des organismes. Nous avons testé la réponse de ces traits à l’histoire des paysages, leur configuration et leur composition. Nous montrons qu’il existe une réponse générale de la diversité fonctionnelle multitrophique aux changements d’utilisation des terres. Nous mettons en évidence l’importance des effets historiques du changement d’utilisation des terres à l’échelle des paysages agricoles menaçant le maintien de communautés fonctionnellement diversifiées dans ces paysages. En considérant un set de traits multiples, notre travail a permis d’approcher certains mécanismes par lesquels les changements d’utilisation des terres présents et passés impactent différentes facettes de la biodiversité. Enfin, l’utilisation des traits fonctionnels a permis d’appréhender l’importance des interactions trophiques et leur implication dans la structuration des communautés animales dans les milieux agricoles. / Understanding how grassland biodiversity responds to land use intensification is crucial for both biodiversity conservation and the management of key ecosystem services in agricultural landscapes. My PhD aims at (i) identifying and generalising the effects of land use intensification operating at different spatial and temporal scales across multiple taxonomic groups and trophic levels (plants, herbivores, pollinators, predators and top-predators) ; (ii) investigating the underlying mechanisms of biodiversity response, and particularly the role of trophic interactions. We used multiple functional traits related to resource acquisition, the size of the organisms and their mobility. We tested how multitrophic functional trait diversity responded to landscape history, composition and heterogeneity. Considering multiple taxonomic groups simultaneously, our study brings out a clear response of overall biodiversity to land use intensification. We found that legacy effects of land use intensification operating at the landscape scale are major drivers of present-day multitrophic functional trait diversity in agricultural landscapes. By considering a core set of organismal traits reflecting similar functions across trophic levels, our approach reveals multiple dimensions by which land use intensification filters out biodiversity over time and allows us to generalise its effect across multiple trophic levels and trait-spectrum. Finally, trait-based approach allowed us to assess the importance of trophic interactions and their contribution in shaping animal communities in agricultural landscapes.