Degré zéro. Portée et limites de la théorie de l’artialisation dans la perspective d’une politique du paysage

La théorie de l’artialisation développée par Alain Roger (1997) a longtemps été et est encore une référence, en France tout particulièrement, dans le champ théorique sur le paysage. Cet article résume le débat sur le paysage qui a été contemporain de l’émergence de cette théorie. La définition du paysage proposée par Alain Roger est ensuite soumise à une double critique : interne et externe. La critique interne met en évidence un biais logique dans l’utilisation de la catégorie de patrimonialisation et montre que ce biais interdit à cette théorie de fonder, comme le prétend Alain Roger, une politique du paysage. La seconde, externe, suggère que cette théorie n’explique pas comme elle le soutient l’émergence du paysage. Dans les deux cas, ces limites sont dues à l’absence d’élaboration du lien entre le paysage et son substrat : le degré zéro du paysage, comme l’a nommé Alain Roger.The theory of artialisation developed by Alain Roger (Roger, 1997) is still a conceptual benchmark in landscape theory, particularly in France. This paper briefly reviews the French debate about landscape that was coeval with the emergence of this theory. The definition of landscape implied by Roger’s theory is then submitted to a double criticism,both internal and external. The internal criticism highlights a logical gap in the use of the notion of patrimonialization, which prevents this theory from reaching operativity in the design of landscape policy,although it claims to do so. The second external criticism suggests that this theory does not explain the genesis of landscapes, once again contrary to its claims. In both cases, the gap is due to the missing link between the landscape and its substratum, degré zéro, as Alain Roger has named it

Unexpected Wind Power ‘Potentials’: The Art of Planning with Inherited Socio-Geographical Configurations (France)

International audienc

Explaining the magnetic moment reduction of Fullerene encapsulated Gadolinium through a theoretical model

We propose a Theoretical model accounting for the recently observed reduced magnetic moment of Gadolinium in fullerenes. While this reduction has been observed also for other trivalent rare-hearth atoms (Dy3+, Er3+, Ho3+) in fullerenes and can be ascribed to crystal field effects, the explanation of this phenomena for Gd3+ is not straightforward due to the sphericity of its ground state (S=7/2, L=0). In our model the momentum lowering is the result of a subtle interplay between hybridisation and spin-orbit interaction

Impact de fonte tardive ou hâtive de neige et de glace sur l'export de microalgues dans la mer de Beaufort

Les observations dérivées d’images satellites suggèrent que la réduction récente de l’étendue de la glace de mer a entraîné une augmentation de la production primaire en Arctique. Cependant, peu d’observations in situ sont disponibles pour confirmer ces estimations, en particulier au début de la saison de production. Les cellules de microalgues collectées dans des pièges à particules déployés sur trois sites de la mer de Beaufort au cours de trois à cinq cycles annuels de 2011 à 2017 ont été énumérées et identifiées afin d'étudier les changements dans le timing, l'abondance et la composition de l’export de microalgues en relation avec les variations dans le couvert de neige et de glace de mer. Les diatomées ont dominé les flux de microalgues avec différents assemblages au printemps-été (avril à août; Fragilariopsis spp. et Thalassiosira spp.) et à l'automne (septembre-novembre; Cylindrotheca closterium). La fonte des neiges ou la débâcle des glaces s'est produite dès la fin avril (2016) et jusqu'à la mi-août (2013). Les flux printemps-été des diatomées variaient de 0,05 à 500 mg C m⁻² (< 10⁵ à 1,25 x 10¹⁰ cellules m⁻²) et étaient négativement corrélés à la date de la fonte des neiges (r² = 0,35, n = 12) et à la débâcle des glaces (r² = 0,32, n = 12). L’exportation de l’algue de glace Nitzschia frigida reflète la libération des algues de glace au début de la fonte des neiges. Les flux maximaux de diatomées ont été systématiquement observés peu de temps après la débâcle des glaces. La contribution en pourcentage du flux de carbone associé aux microalgues (MC) au flux de carbone organique particulaire (POC) augmente avec l'ampleur du flux de diatomées. L'ampleur du flux de diatomées automnal relativement faible n'était pas corrélée de manière significative à la date de formation du couvert de glace (r² = 0,24, n = 10). Nos résultats sont généralement cohérents avec les observations satellitaires suggérant une augmentation de la biomasse de microalgues et le développement d’une prolifération de diatomées à l’automne en réponse à une saison libre plus longue dans les mers arctiques. Les variations à l’échelle régionale dans le régime de neige et de glace de mer ont une incidence directe sur le moment et l’ampleur de la production de microalgues et sur sa contribution à l’export de POC dans la mer de Beaufort. Avec le réchauffement climatique, la réduction continue du couvert de neige et de glace dans les mers arctiques entraînera une augmentation des flux de carbone vers le benthos et, potentiellement, une séquestration du carbone en profondeur.Microalgal cells collected in sediment traps deployed at three sites in the Beaufort Sea during three to five annual cycles from 2011 to 2017 were enumerated and identified to investigate changes in the timing, abundance and composition of microalgal export in relation to variations in snow and sea ice cover. Diatoms dominated the microalgal fluxes with different assemblages in spring-summer (April to August; Fragilariopsis spp. and Thalassiosira spp.) and autumn (September-November; Cylindrotheca closterium). Snowmelt or ice breakup occurred as early as late April (2016) and as late as mid-August (2013). The magnitude of the spring-summer diatom flux varied from ~0.05 to 500 mg C m⁻² (< 10⁵ to 1.25 x 10¹⁰ cells m⁻²) and was negatively correlated to snowmelt date (r² = 0.35, n = 12) and sea-ice breakup date (r² = 0.32, n = 12). The export of the ice-obligated algae Nitzschia frigida reflected the release of sea ice algae at the onset of snowmelt. Peak diatom fluxes were consistently observed shortly after seaice break-up. The percent contribution of microalgal carbon to the particulate organic carbon (POC) flux increased with the magnitude of the diatom flux. The magnitude of the relatively small autumnal diatom flux was not significantly correlated to freeze-up date (r² = 0.24, n = 10). Our results are generally consistent with satellite observations suggesting an increase in microalgal biomass and the development of an autumn diatom bloom in response to a longer ice-free season in Arctic seas. Variations at the regional scale in the snow and sea-ice regimes directly impact the timing and magnitude of microalgal production and its contribution to POC export in the Beaufort Sea. With global warming, the ongoing reduction of the sea-ice cover in Arctic seas will result in increased carbon fluxes to the benthos and, potentially, carbon sequestration at depth

Communs paysagers et devenirs éoliens opposés

Cet article part d’un projet éolien contesté et conflictuel dans un village de Seine-et-Marne (France). Il suit l’émergence et la structuration de trajectoires d’opposants dans leur constitution progressive, en explorant les rôles et les devenirs opposés de communs paysagers. À la croisée de ces devenirs opposants et paysagers, l’analyse met en lumière les modalités selon lesquelles, en France, l’accompagnement institutionnel échoue à articuler des communs paysagers hétérogènes pour soutenir l’émergence de projets éoliens partagés.This article starts with the opposition to a wind farm project which led to conflict in a village in Seine-et-Marne (France). It follows the emergence and the gradual structuring of the trajectories of the opposing parties by exploring the roles and different opposing projects for shared landscapes. At the intersection between these conflicting changes and projected landscapes, the analysis sheds light on the reasons why institutions in France fail to establish the connection between heterogeneous shared landscapes to support the emergence of joint wind farm projects

Observation and theoretical description of the pure Fano-effect in the valence-band photo-emission of ferromagnets

The pure Fano-effect in angle-integrated valence-band photo-emission of ferromagnets has been observed for the first time. A contribution of the intrinsic spin polarization to the spin polarization of the photo-electrons has been avoided by an appropriate choice of the experimental parameters. The theoretical description of the resulting spectra reveals a complete analogy to the Fano-effect observed before for paramagnetic transition metals. While the theoretical photo-current and spin difference spectra are found in good quantitative agreement with experiment in the case of Fe and Co only a qualitative agreement could be achieved in the case of Ni by calculations on the basis of plain local spin density approximation (LSDA). Agreement with experimental data could be improved in this case in a very substantial way by a treatment of correlation effects on the basis of dynamical mean field theory (DMFT).Comment: 11 pages, 3 figures accepted by PR

Landscape and the energy transition: Comparing the emergence of wind energy

Debido al reconocimiento generalizado de la realidad del calentamiento global, cada vez hay más países inmersos en el proceso de introducir energías alternativas, como la energía eólica. En este artículo nos centramos en la transformación del espacio que se ha producido como consecuencia de estas nuevas políticas energéticas. Los paisajes constituyen la plasmación (o no) de las visiones y las decisiones políticas. Analizamos el desarrollo de la energía eólica en tres países europeos, Francia, Alemania y Portugal, desde la perspectiva de un estudio etnográfico del paisaje. Proponemos que la implementación efectiva de un futuro bajo en carbono depende en gran medida de las respectivas culturas administrativas nacionales, de las prácticas e iniciativas locales, y de la percepción del espacio a nivel local. En los tres países estudiados, identificaremos las posibles fuentes de tensión y exploraremos cómo se superan (o no) a nivel local, para así dar paso a la aparición de (nuevos) paisajes de energía eólica. Comparamos el papel de las culturas paisajísticas, las instituciones y las prácticas en el desarrollo y la resolución de conflictos sobre el despliegue de la energía eólica. Due to the global acceptance of the reality of global warming, ever more countries are in the process of implementing alternative energies such as wind power. In this article, we focus on the transformation of space as a consequence of these newly established alternative energy policies. Landscapes are the level at which political visions and policy decisions endorse (or not) their very materiality. We analyze the deployment of wind power in three European countries, France, Germany and Portugal through the lens of ethnographic landscape studies. We argue that the successful implementation of low carbon futures is highly dependent on the respective national cultures of administration as well as on local practices, initiatives and perceptions of space at the local level. In each of the countries under scrutiny, we analyze the way in which wind power and landscape issues are framed, we point at potential tensions and explore how these are overcome (or not) at the local level so as to give way for the emergence of (new) wind power landscapes. We compare the role played by landscape cultures, institutions or practices in the development and resolution of tensions over the deployment of wind energy

Understanding the material dimensions of the uneven deployment of renewable energy in two Italian regions

Drawing on empirical material from two Italian regions, we show how various material dimensions have affected the spatial distribution and deployment of renewable energy (RE), in particular solar and wind energy. The paper draws on an approach to the analysis of materiality originally developed in the extractive industries literature, including fossil fuels. The paper acknowledges that RE forms have significantly fewer material components compared with coal, oil and gas and the other extractive industries. Nevertheless, the deployment of RE, the process of turning renewable ‘natural resources’ into productive use as viable forms of energy through stages of energy conversion, storage, transmission and distribution has material aspects like those involved in the deployment of fossil fuels. This paper aims to show how understanding these aspects of renewable energy offers an opportunity to unpack and explain how particular RE paths come to be favoured or hampered, and yields useful insights into the spatial unevenness and variation of RE deployment at the regional level. Italy has introduced a system of renewable energy incentives and between 2010 and 2012 experienced impressive growth in the renewable energy sector. The paper shows how the significant spatial variation in renewable energy deployment in the regions of Apulia and Tuscany can be explained in terms of the influence that the material dimensions exercised in relation to renewable energy deployment processes. The paper suggests that understanding the material dimensions of renewable energy offers useful insights into how and why RE realises – and quite often fails to realise – its potential in specific forms, spaces and places

Forest canopy cover determines invertebrate diversity and ecosystem process rates in depositional zones of headwater streams

1. Previous studies of the ecological linkages between forest and headwater streams have focused primarily on patterns and processes in erosional habitats, typically riffles. Depositional zones trap large amounts of sediments and particulate organic matter, suggesting that they may be important for forest–stream linkages. 2. We studied the invertebrate benthos and two key ecological processes, surface sediment reworking and leaf litter breakdown, in the depositional zones of streams bordered by contrasting riparian vegetation. We compared three stream reaches, draining open canopy forest regenerating after recent clearcut harvesting, with reaches on three different streams bordered by older forests with closed canopies. We also assessed whether, and to what extent, forest canopy cover determined abiotic factors at the reach scale (physicochemistry of stream water) and patch scale (sediment properties). 3. Depositional zones in both types of stream harboured a taxonomically and functionally diverse invertebrate community, including efficient sediment reworkers and specialised shredders. Higher diversity was found in open canopy than in closed canopy streams, despite similarities in habitat morphology and sediment properties. 4. Water temperature and sediment reworking rate were higher in open canopy forest than in closed canopy forest. As rates of sediment reworking, adjusted for temperature, did not differ between forest types, temperature was probably a key factor linking the forest canopy to stream depositional zones. The rates of leaf litter breakdown sometimes varied substantially between streams, but no consistent forest effect was detected for this process. 5. Temperature-adjusted rates of surface sediment reworking and litter breakdown were positively correlated with the density of invertebrates that rework sediments and shredders, respectively. A relationship between these two ecological processes was found across depositional zones in closed canopy forest, but not in open canopy forest. 6. This study on depositional zones provides new evidence of the strong linkage between forest and headwater streams. By moderating stream summer temperature, riparian canopy cover has the potential to affect invertebrate metabolic rates and, indirectly, the intensity of surface sediment reworking. However, other factors, such as the quality and diversity of basal trophic resources, may also account for invertebrate diversity pattern across streams and the positive relationship between litter breakdown and sediment reworking in closed canopy forest