Les TIC dans les collectifs diasporiques : étude des Bretons à New York

Dans cet article, nous nous intéressons au collectif de la diaspora bretonne à New York. En tant que réseau de connaissances diasporiques, ce collectif d’expatriés agit pour le développement de son pays d’origine. Nous étudierons ici les usages des technologies de l’information et de la communication (TIC) opérés par ce collectif, au travers des traces numériques. Cette analyse nous permet de caractériser trois phases d’activités successives qui correspondent à différents régimes d’engagement. Notre analyse met en lumière les interactions qui existent entre les outils techniques, le type de relation à l’intérieur du collectif et les connaissances produites par cet ensemble.In this paper, we focus on a group of Breton people settled in New York City. This diaspora knowledge network is acting for the development of its country of origin. We focus on this collectivity’s uses of information and communication technologies by examining their logs. This analysis describes three different stages that correspond to different régimes d’engagement. Our analysis highlights intereactions between technological tools, the types of relationships within the collectivity and the knowledge produced by the group.Este artículo se interesa en el colectivo de la diáspora bretona en Nueva York. En tanto que red de conocimiento diaspórico, este colectivo de expatriados actúa en favor del desarrollo de su país de origen. A través de rastros digitales, se estudian los usos de las tecnologías de la información y de la comunicación (TIC) utilizadas por dicho colectivo. Este análisis nos permite caracterizar tres fases de actividades sucesivas que corresponden a los diferentes regímenes de compromiso. Tal análisis arroja luz sobre las interacciones existentes entre las herramientas técnicas, el tipo de relación existente en el interior del colectivo y los conocimientos producidos por este conjunto

Formats techniques, formats communautaires, formats d’engagement : le cas d’une communauté diasporique

A l'image des communautés virtuelles traitées par Howard Rheingold, la plupart des travaux sur cette thématique partent de l'offre technique pour analyser la communauté qui se développe autour de (sur, dans, avec, grâce à) cette infrastructure (l'incertitude sur la préposition qui va qualifier la relation est significative). A partir de cette approche, on débouche aisément sur une adéquation peu interrogée entre offre technique et communauté sans possibilité de comparer les différentes communautés entre elles. Il est en effet impossible à partir de ce point de départ de penser la diversité des supports techniques qui peuvent concourir à faire tenir la communauté en question et à redéfinir ses frontières pertinentes (...)

Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality

Urban gardens are popular green spaces that have the potential to provide essential ecosystem services, support human well-being, and at the same time foster biodiversity in cities. We investigated the impact of gardening activities on five soil functions and the relationship between plant (600 spp.) and soil fauna (earthworms: 18 spp., springtails: 39 spp.) in 85 urban gardens (170 sites) across the city of Zurich (Switzerland). Our results suggest that high plant diversity in gardens had a positive effect on soil fauna and soil multifunctionality, and that garden management intensity decreased plant diversity. Indices of biological activity in soil, such as organic and microbial carbon and bacterial abundance, showed a direct positive effect on soil multifunctionality. Soil moisture and disturbance, driven by watering and tilling, were the driving forces structuring plant and soil fauna communities. Plant indicator values proved useful to assess soil fauna community structure, even in anthropogenic plant assemblages. We conclude that to enhance soil functions, gardeners should increase plant diversity, and lower management intensity. Soil protective management practices, such as applying compost, mulch or avoiding soil tilling, should be included in urban green space planning to improve urban biodiversity and nature’s contribution to people

A gardener’s influence on urban soil quality

Gardens are hot spots for urban biodiversity and provide habitats for many plant and animal species, both above- and below-ground. Furthermore, gardens provide a wide range of ecosystem services, including carbon (C) storage and nutrient cycling. Although the soil is the foundation of sustainable gardens providing those ecosystem services, very little is known about the consequences of garden management on soil quality. Here we present a comprehensive assessment of urban garden soil quality, including biotic and abiotic site characteristics combined with land-use history and garden management information in a multivariate evaluation. A set of 44 soil quality indicators was measured at 170 sites of 85 gardens in the city of Zurich, Switzerland, comprising contrastingly managed garden habitats along a gradient of urban density. Taken together, our results show that garden management was the driving factor that influenced soil quality and soil functions. Eco-physiological soil quality indices were useful to identify differences in disturbance and intensity of soil use, showing highest microbial [microbial biomass (Cmic)/soil organic carbon (SOC)] and lowest metabolic (qCO2) quotients in perennial grass sites compared to annual vegetable sites. Despite the intensity of soil disturbance in annual vegetable and flower beds, the highest endogeic earthworm biomass and diversity were found in those habitats. Whereas decomposition of green tea bags was higher in grass sites. Soil heavy metal contents varied considerably and could not be linked with garden management practices, but with spatial patterns of industry and traffic. We conclude that understanding soil quality in urban ecosystems needs multi-indicator frameworks to capture the complexity of soil characteristics and the influencing factors in space and time. This study contributes to a better understanding of urban gardens and enhances the development of sustainable soil management strategies aimed at long-term improvement of soil quality and related ecosystem services in cities

Litter decomposition driven by soil fauna, plant diversity and soil management in urban gardens

In the face of growing urban densification, green spaces in cities, such as gardens, are increasingly important for biodiversity and ecosystem services. However, the influences of urban green space management on biodiversity and ecosystem functioning (BEF) relationships is poorly understood. We investigated the relationship between soil fauna and litter decomposition in 170 urban garden sites along a gradient of urbanisation intensity in the city of Zurich, CH. We used litter bags of 1 and 4 mm mesh size to evaluate the contribution of soil meso- and macrofauna on litter decomposition. By using multilevel structural equation models (SEM), we investigated direct and indirect environmental effects and management practices on litter decomposition and litter residue quality. We evaluated the role of taxonomic, functional and phylogenetic diversity of soil fauna species on litter decomposition, based on a sample of 120 species (81,007 individuals; 39 collembola, 18 earthworm, 16 isopod, 47 gastropod species). We found highest litter decomposition rates using 4 mm mesh size litter bags, highlighting the importance of soil macrofauna. Urban warming, a proxy for urbanisation intensity, covaried positively, whereas soil disturbances, such as intensive soil and crop management, were negatively correlated with decomposition rates. Interestingly, soil fauna species richness decreased, with the exception of gastropods, and soil fauna abundance increased with urban warming. Our data also show that plant species richness positively affected litter decomposition by increasing soil fauna species richness and microbial activity. A multivariate analysis of organic compounds in litter residues confirmed the importance of soil fauna species richness and garden management on litter decomposition processes. Overall, we showed, that also in intensively managed urban green spaces, such as gardens, biodiversity of plants and soil fauna drives key ecosystem processes. Urban planning strategies that integrate soil protecting management practices may help to maintain important ecosystem services in this heavily used urban environment

Urban soil quality assessment - a comprehensive case study dataset of urban garden soils

Soil is the foundation of ecosystem functioning in urban green spaces and provides key ecosystem

Sociologie de la composition des collectifs web 2.0 : le cas de la diaspora bretonne

The Breton diaspora is a prolific field to question the composition of web 2.0 collectives. Web 2.0 collectives refer to new types of assemblies that appears within the web. The problem is theses assemblies are only socially or technically questioned. Observing web collectives through diaspora is useful to construct a new point of view that embrace cognitive, social and technical approaches. With pragmatic sociology and the actor network theory we designed an original method to analyse the digital data produced by web collectives. We selected three collectives from the larger field of the breton diaspora, to analyse them with accuracy. The results show different kinds of mediators which composed web collectives. Far from creating homogeneity, technologies are introducing much more differences. Web collectives present a particular configuration of social, technical and cognitive elements to explore and innovateLa diaspora bretonne offre un terrain fertile pour questionner la composition des collectifs web 2.0. Nous faisons ici référence aux nouvelles formes de regroupements qui émergent avec le web mais que l'on aborde trop souvent en distinguant les problématiques sociales des problématiques techniques. En recourant aux diasporas, nous décentrons notre regard pour aborder ces collectifs selon un point de vue tout à la fois technique, social et cognitif. Dans ce travail, nous recourrons à la sociologie de la traduction et à la sociologie pragmatique pour construire une méthodologie basée sur l'analyse des traces numériques produites par les collectifs. Après avoir identifié au sein de la diaspora bretonne trois collectifs correspondants à nos critères, nous les avons analysé à l'aide de trois formats, afin d'identifier les médiateurs de différentes natures qui les composent. Nos résultats démontrent que les collectifs web sont des regroupements proliférants et hétérogènes. Loin d'homogénéiser les cultures ou les civilisations, les technologies web favorisent l'exploration et la combinaison. Les collectifs web détiennent une dynamique et un fonctionnement en proche qui favorisent l'innovatio

Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality

Urban gardens are popular green spaces that have the potential to provide essential ecosystem services, support human well-being, and at the same time foster biodiversity in cities. We investigated the impact of gardening activities on five soil functions and the relationship between plant (600 spp.) and soil fauna (earthworms: 18 spp., springtails: 39 spp.) in 85 urban gardens (170 sites) across the city of Zurich (Switzerland). Our results suggest that high plant diversity in gardens had a positive effect on soil fauna and soil multifunctionality, and that garden management intensity decreased plant diversity. Indices of biological activity in soil, such as organic and microbial carbon and bacterial abundance, showed a direct positive effect on soil multifunctionality. Soil moisture and disturbance, driven by watering and tilling, were the driving forces structuring plant and soil fauna communities. Plant indicator values proved useful to assess soil fauna community structure, even in anthropogenic plant assemblages. We conclude that to enhance soil functions, gardeners should increase plant diversity, and lower management intensity. Soil protective management practices, such as applying compost, mulch or avoiding soil tilling, should be included in urban green space planning to improve urban biodiversity and nature's contribution to people.publishe