Handle with care! Post-crisis growth in the EU

In this policy brief, Jean Pisani-Ferry and Bruno van Pottelsberghe show that although the crisis originated in the US, Europeâ??s outlook has deteriorated faster and more sharply leading to the worst crisis observed during the post-war era. However, the length of the crisis matters at least as much at its depth, and policymakers should not overlook the medium term consequences of their actions.

Un regard critique sur Tré Maroua (Le Saix, Hautes-Alpes, France), la coupe candidate pour le PSM du Berriasien

The Tré Maroua site in SE France was recently selected by the Berriasian Working Group (BWG) of the International Subcommission on Cretaceous Stratigraphy (ISCS) as the candidate locality for the reference section of the Berriasian Global Boundary Stratotype Point (GSSP). However, on the basis of our preliminary investigation at this site and also from field observations over a larger area, this candidate section is paleogeographically located on a deep-water slope riddled with successive erosional surfaces, stratigraphic hiatuses and breccias. It does not meet at least four of the five "geological requirements for a GSSP". Accordingly, in our opinion, its candidacy must be definitely precluded.Le site de Tré Maroua en SE France a récemment été sélectionné par le Groupe de Travail Berriasien de la Sous-Commission Internationale de Stratigraphie du Crétacé comme la localité candidate pour la coupe de référence du Point Stratotypique Mondial (PSM) du Berriasien. Cependant, sur la base de nos recherches préliminaires effectuées sur ce site et dans les environs, il apparaît que cette coupe paléogéographiquement située sur un paléotalus profond comportant des surfaces d'érosion emboîtées, des hiatus stratigraphiques importants et des brèches de resédimentation. Elle ne répond pas à au moins quatre des cinq "exigences géologiques pour un PSM". Par conséquent, à notre avis, sa candidature devrait être définitivement écartée

Memos to the new Commission- Europe's economic priorities 2010-2015

These Memos, addressed to the next Commission President and to the new European commissioners, are written by Bruegel Scholars and edited by Senior Research Fellow André Sapir and focus on key economic aspects of EU policy-making. The new Commission will enter office at a challenging time for Europe, the EU and the Commission itself. The crisis has clearly exposed weaknesses in EU governance which need to be addressed and the memos make a number of concrete recommendations of relevance for major economic fields, as well as for the EU and Commission as a whole. Addressing the next Commission President, André Sapir and Jean Pisani-Ferry propose that effective leadership will be necessary to give strategic direction to the Commission, "you [the president] should therefore be ready to fight for ideas and take risks" (JPF-AS). The Memos suggest that the EU will need to assert a position on commonly agreed rules, propose new solutions and, importantly, has an opportunity now to redefine the European narrative in the global arena. Focusing on the most important economic questions at EU level, the Bruegel memos are intended to be strategic, outlining the state of affairs that will be met by the new Commission and the key challenges and priorities they will need to consider over the next five years.

A high order purely frequency-based harmonic balance formulation for continuation of periodic solutions

Combinig the harmonic balance method (HBM) and a continuation method is a well-known technique to follow the periodic solutions of dynamical systems when a control parameter is varied. However, since deriving the algebraic system containing the Fourier coefficients can be a highly cumbersome procedure, the classical HBM is often limited to polynomial (quadratic and cubic) nonlinearities and/or a few harmonics. Several variations on the classical HBM, such as the incremental HBM or the alternating frequency/time domain HBM, have been presented in the literature to overcome this shortcoming. Here, we present an alternative approach that can be applied to a very large class of dynamical systems (autonomous or forced) with smooth equations. The main idea is to systematically recast the dynamical system in quadratic polynomial form before applying the HBM. Once the equations have been rendered quadratic, it becomes obvious to derive the algebraic system and solve it by the so-called ANM continuation technique. Several classical examples are presented to illustrate the use of this numerical approach.Comment: PACS numbers: 02.30.Mv, 02.30.Nw, 02.30.Px, 02.60.-x, 02.70.-

Matières organiques des sols forestiers et changements climatique et atmosphérique

La matière organique des sols (MOS) constitue le plus grand réservoir de carbone des écosystèmes terrestres et elle est une composante majeure de la fertilité. Son évolution sous l’impact des changements atmosphériques et climatiques est porteuse d’enjeux essentiels à moyen et long terme, à l’échelle globale comme à l’échelle locale. Nous présentons ici une synthèse des connaissances sur cette évolution des MOS dans les forêts. Les principales méthodes d’étude sont les comparaisons d’inventaires pédologiques, l’interprétation de corrélations spatiales avec le climat en tendances temporelles, les suivis expérimentaux en laboratoire ou en forêt des flux d’entrée et de sortie du carbone dans le sol, et toute une gamme de modèles visant à assembler ces connaissances et à prédire l’évolution des MOS. Les résultats confirment qu’il faut s’attendre à plus ou moins long terme à un appauvrissement en MOS, dû au réchauffement, dans les forêts boréales et tempérées. Cependant, les dépôts azotés ont un effet positif sur le stockage de matière organique dans le sol, qui n’est pas encore intégré dans les modèles terrestres à l’échelle globale. Enfin, les expérimentations d’enrichissement de l’air en CO2 en forêt n’ont pour l’instant pas d’effet sur le stockage de carbone dans le sol, mais on peut s’attendre à des effets positifs à plus long terme. Sur le plan qualitatif, les dépôts azotés et le réchauffement contribuent à réduire la limitation de la fertilité par l’azote, et il est prévisible que la limitation par le phosphore gagne en importance relative

Soil properties explain tree growth and mortality, but not biomass, across phosphorus-depleted tropical forests

We observed strong positive relationships between soil properties and forest dynamics of growth and mortality across twelve primary lowland tropical forests in a phosphorus-poor region of the Guiana Shield. Average tree growth (diameter at breast height) increased from 0.81 to 2.1 mm yr-1 along a soil texture gradient from 0 to 67% clay, and increasing metal-oxide content. Soil organic carbon stocks in the top 30 cm ranged from 30 to 118 tons C ha-1, phosphorus content ranged from 7 to 600 mg kg-1 soil, and the relative abundance of arbuscular mycorrhizal fungi ranged from 0 to 50%, all positively correlating with soil clay, and iron and aluminum oxide and hydroxide content. In contrast, already low extractable phosphorus (Bray P) content decreased from 4.4 to <0.02 mg kg-1 in soil with increasing clay content. A greater prevalence of arbuscular mycorrhizal fungi in more clayey forests that had higher tree growth and mortality, but not biomass, indicates that despite the greater investment in nutrient uptake required, soils with higher clay content may actually serve to sustain high tree growth in tropical forests by avoiding phosphorus losses from the ecosystem. Our study demonstrates how variation in soil properties that retain carbon and nutrients can help to explain variation in tropical forest growth and mortality, but not biomass, by requiring niche specialization and contributing to biogeochemical diversification across this region

Translating environments

Far from being inert materials activated by human ingenuity, natural resources come to be made and unmade through ongoing processes of translation, through which they acquire new potentialities and meanings. In this introduction, we review the key concept of translation for anthropology and explore some of its multiple analytical possibilities in the context of human-environment relations. Based on insights offered by the articles in this collection, we propose a twofold definition of environments as both translating subjects and objects of translation. In grounding our analytical definition, we focus on the enactment of material transformations (as the result of both relations of mutual determination with humans and processes of objectification of the environment), the implications of incommensurability and erasure in processes of (attempted) translation, and the indeterminacy that accompanies (re)configurations of materials, relations and values