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Are urban areas better environmentally managed than countries ?
No full textGovernment entities are crucial in implementing effective mitigation and adaptation strategies to cope with climate change. This article introduces an innovative quantitative composite index to assess environmental performance across the city and country levels: a Deterioration of Environmental Performance Index (DEPI). This new index provides valuable and objective insights into the sustainability of territorial development strategies. This article aims to understand how local and national governments address environmental challenges by leveraging these metrics. We compute the annual index evolution for ten countries from 2001 to 2020. Our findings reveal that, compared to baseline levels, environmentally harmful outcomes generally decrease more significantly (or increase less sharply) over time. In addition, countries tend to outperform their cities in managing five critical environmental impacts: air pollution, river flooding, coastal flooding, forest fires, and heatwaves
Extreme flood deposits in the Roya Valley during the Holocene: characterisation and recurrence intervals
No full textInternational audienceFloods are among the costliest natural disasters, causing extensive damage and fatalities worldwide. Mountainous regions of the Mediterranean Alps are highly vulnerable to extreme hydrological events, whose frequency is increasing in the context of climate change favouring convective storms. In October 2020, the Roya valley was struck by an extreme hydrological event. The amount of rainfall (return period >1000yr) and discharge (>100yr), triggered major geomorphological changes, including subsantial channel widening, slope destabilisation and extensive bank erosion. This study provides unprecedented sedimentological data on torrential dynamics in the Roya Valley, based on 14C and OSL dating of newly exposed flooding deposits following Storm Alex. Five clusters of preserved fluvial and torrential deposits ranging from the Younger Dryas–Holocene transition to the Little Ice Age are identified. These preservation clusters correspond to periods of wetter condition and anthropogenic influence. By combining sedimentological analyses with documented pollen and sediments records from lakes in the Mercantour massif, as well as historical archives, this study presents one of the first flood-frequency reconstructions for a Mediterranean Alpine catchment over a multi-millennial timescale. Past flooding events (on centennial to millennial scales) leave distinctive sedimentary signatures, characterised by thick deposits and the mobilisation of coarse particles, before being reworked within the broader autogenic dynamics of the river system. Reconstructing the frequency and occurrence of past extreme flood events provides key insights into the conditions under which such events occurr, and offers valuable information for the development of flood-risk scenarios, particularly in mountainous areas that are among the most affected by contemporary climate change
Spectroscopic properties of amber chromophore in silicate glasses
No full textInternational audienceThe structure of the amber chromophore, a Fe3+ oxysulfide complex, is investigated in a suite of soda‐lime glasses, using optical absorption spectroscopy (UV‐Vis‐NIR), Raman spectroscopy, and electron paramagnetic resonance (EPR). These spectroscopic data on glasses containing a similar Fe‐content show an outstanding linear variation as a function of S concentration. This chemical dependence allows us to assign a composite Raman band at 420 cm-1 to the presence of Fe‐S bonds. EPR data indicate that the classical EPR signal of Fe3+ in glasses coexists with another signal showing an axial distortion of the Fe3+ site, due to O2- ‐S2- substitution. These data support the presence of tetrahedral Fe3+ in a mixed ligand configuration with three O and one S neighbors. The two optical absorption bands observed in the UV range, near 24,200 and 34,000 cm-1, are due to S2- —Fe3+ and O2- —Fe3+ charge transfer transitions within the chromophore, respectively. The former is at the origin of a broad Gaussian‐shaped absorption band, causing a tail that extends into the visible range. The absence of a discrete absorption band in the visible range, together with a continuously increasing absorption with increasing wavenumbers, causes the original brown color of amber glasses. The amber chromophore concerns only a minority of Fe3+ sites, as shown by EPR. However, as the electronic transitions associated with charge transfer are allowed and intense, the amber chromophore has an efficient coloring power. The Fe2+ optical absorption spectrum remains identical to that observed in soda‐lime glasses containing iron, without specific site distortion, showing the absence of substituted sulfide ligands in the coordination site of Fe2+ . The control of the melting atmosphere conditions for chromophore formation plays a crucial role. Glass melting experiments in platinum or graphite crucibles are consistent with the literature, indicating that glasses develop an amber color only under intermediate redox conditions, estimated to correspond to an oxygen partial pressure in the range of 10-10 to 10-8 atm. Above and below this range, S2- and Fe3+ do not coexist, and the glass is colorless
Insights into L4 ordinary chondrites from the Gueltat Zemmour fall, Morocco: Modal mineralogy, chondrule characteristics, and magnetic signatures
No full textInternational audienceThe Gueltat Zemmour meteorite, an L4 ordinary chondrite that fell in southern Morocco on 21 August 2018, was investigated through petrographic, mineralogical, geochemical, and magnetic analyses. X-ray diffraction indicates a modal composition dominated by forsteritic olivine (39.7(4) weight %), enstatite (32.4(3) %), plagioclase (7.3(1) %), troilite (3.7(1) %), and Fe–Ni metal phases (16.9 %, kamacite-dominated). Chondrules represent ∼82 % of the surface area, with porphyritic olivine–pyroxene and porphyritic olivine as the dominant types, and an average diameter of ∼500 μm. Gamma spectrometry confirmed the presence of short-lived cosmogenic radionuclides (e.g., 7Be, 22Na, 26Al, 48V), with a 22Na/26Al activity ratio consistent with a recent fall. Magnetic hysteresis properties and the preservation of tetrataenite in cloudy zone textures indicate slow cooling during parent-body metamorphism. The sulfide assemblage, dominated by troilite with rare pentlandite, combined with Fe/S (∼0.98) and Fe_ox/Si (∼0.36) ratios, reflects reducing redox conditions near the iron–wüstite buffer and minimal secondary alteration. These integrated results confirm the classification of Gueltat Zemmour as an equilibrated L4 chondrite and provide new insights into the thermal history and redox state of L-group parent bodies, contributing to a broader understanding of the early evolution of ordinary chondrites
No impact of black-eye symptom on foraging behaviour and reproductive success of Northern gannets following highly pathogenic avian influenza
No full textInternational audienceHighly Pathogenic Avian Influenza Virus (HPAIV) is currently causing major wild animal population crashes all over the world including Antarctica. Yet, there are important knowledge gaps on the implications of long-lasting symptoms for the ecology of surviving individuals and the conservation of their populations. Using GPS tracking devices and long-term demographic data, we examined the effects of HPAIV on a seabird population of Northern gannets (Morus bassanus) in the colony of Rouzic, France. One year after the HPAIV outbreak of 2022, the breeding gannet population declined by 38 % and 22.3 % of surviving breeders were zombie birds: they had darkened irises, a black-eye symptom indicative of past infection to HPAIV. Importantly, we demonstrate that black eyes were not associated with detectable differences in the foraging behaviour and habitat use of surviving breeding gannets. Compared to years prior to the outbreak, the foraging effort of breeding individuals was lower and breeding success was higher, aligning with Ashmole's halo hypothesis, which posits that smaller seabird populations face lower intra-specific competition for food in the vicinity of their breeding colony and thereby, have a reduced foraging range. Our results highlight the importance of density-dependant mechanisms in population responses to sudden mass-mortalities, but raise conservation concerns, especially for species facing cumulative threats. In the long-term, locally depleted populations may reach critical thresholds where individual abundance and productivity may not be sufficient to maintain a positive demographic growth rate, ultimately leading to local population extinctions
Ecological and management drivers of pest regulation via multitrophic pathways in tropical insular agroecosystems
No full textInternational audienceHighlights: • In La Réunion agroecosystems, field vegetation diversity boosts arthropod diversity. • Crop pests and damage decrease with increasing natural enemy diversity. • Pest regulation service benefits from field non-crop vegetation diversity. • Management and landscape factors also affect trophic cascades. • Vegetation diversity effects can outweigh management and landscape factors.Abstract: Natural pest regulation services provided by arthropod natural enemies are a cornerstone of ecological intensification. While vegetation diversification is known to support natural enemy communities, its relative contribution and interactions with other drivers for pest regulation services remains unclear, especially in dynamic and diversified smallholder agroecosystems under the tropics. In this study, we investigate how crop and non-crop field vegetation diversity, farming practices, climatic and landscape parameters jointly shape arthropod community structure and their services in the aerial and ground strata in tropical market gardening systems on La Réunion Island. We surveyed 22 open-field market gardening systems during two seasons. Using a multitrophic, piecewise structural equation modeling approach, we assessed direct and indirect cascading effects of local and landscape factors on arthropod diversity and pest regulation services. Results show that in aerial communities, non-crop vegetation richness generated a positive bottom-up trophic cascade. It enhanced herbivore diversity which, in turn, increased natural enemy richness, ultimately reducing pest abundance and crop damage, particularly during the dry season. In contrast, insecticide use suppressed natural enemy richness and reduced the effectiveness of pest regulation. Ground-dwelling communities were more strongly influenced by landscape fragmentation, semi-natural habitat cover, and temperature, with less evidence for structured trophic cascades. Overall, beneficial cascading effects of vegetation on pest regulation services in above-ground communities may outweigh the impacts of other management and landscape drivers. These findings underscore the potential of promoting vegetation diversity and reducing pesticide use as key strategies for enhancing natural pest regulation in tropical smallholder agroecosystems
Optimal structures of crop irrigation strategies with state constraints
No full textInternational audienceWe investigate an optimal control problem of crop irrigation with non-autonomous and non-smooth dynamics. Depending on contexts and objectives, several formulations associated to different constraints and criteria can be derived. Our work aims at providing optimal feedback solutions for these problems by deriving and analyzing the optimality necessary conditions. To this end, we assemble the different problems into a common formulation, and we carry out a dedicated way of handling state constraints. We show that all optimal irrigation strategies belong to a family of simple parameterized time-varying feedback controls, independently of the context and objective, and suitable for computational purposes
Involvement of Taiman in juvenile hormone signaling controlling sexual maturation in a male moth
No full textInternational audienceIn insects, juvenile hormone (JH) is essential for orchestrating reproductive events. For example, in the male moth Agrotis ipsilon, the behavioral response to female sex pheromone is linked to neuronal sensitivity in the primary olfactory centers (antennal lobes, ALs), and the maturation of accessory sex glands (ASGs) are known to be age-and JH-dependent. The molecular basis of this regulatory action of JH is not fully deciphered, and we show here that the heterodimerizing partner of Methoprene-tolerant called Taiman (Tai) is essential for the sexual maturation of male A. ipsilon. Tai expression in ALs and ASGs is elevated from the third day of adult life and is responsible for the acquisition of behavioral responsiveness to the sex pheromone and ASG maturation. Tai-deficient old males exhibited altered sexual behavior and delayed ASG maturation. Moreover, the expression levels of Tai and Krüppel homolog 1 (Kr-h1), an early JH-induced transcription factor, were reduced in ALs and ASGs of JH-deprived and Tai-deficient old males, respectively. Exogenous JH injection into young males resulted in precocious sexual maturation and this JH induction was suppressed by Tai silencing. Our results demonstrate that Tai is an actor of the JH signaling pathway that operates in ALs and ASGs to promote pheromone information processing and consequently the display of sexual behavior in synchrony with ASG maturation, ultimately optimizing male reproductive success. Thus, this study provides additional insights into the molecular mechanisms underlying hormonal regulation of sexual maturation in insects
Biodiversity co-variation patterns in a range of soil organism taxa across highly contrasting ecosystems
No full textInternational audienceSoil biodiversity as a critical component of terrestrial ecosystems and their functioning varies across spatial scales and environmental conditions. However, it remains unclear whether and how biodiversity patterns co-vary among different soil taxa across ecosystems.In this study, we compared diversity patterns of plants, earthworms, nematodes, bacteria, and fungi, as five major groups of soil organisms, across six strongly contrasting ecosystems ranging from mountain peatland to crop fields, including within-ecosystem variation in soil moisture. We hypothesized co-variation in taxonomic richness (alpha diversity) and composition (beta diversity) of multiple groups of soil organisms across ecosystems, moisture conditions and spatial scales.In partial contrast to our initial hypothesis, co-variation in the taxonomic richness among these groups was limited, though significant positive associations were found among bacteria, fungi, and earthworms across all sites. Plant diversity showed distinct associations with soil organism diversity, particularly with earthworms and bacteria, highlighting above-belowground biodiversity linkages. Beta diversity showed substantial co-variation among all soil organism groups, reflecting a spatial coupling of their communities that was influenced by differences in soil moisture conditions. These patterns were more pronounced in near-natural and no-till agroecosystems compared to conventional agricultural systems. Our results highlight that ecosystem type shapes broad-scale taxonomic richness, while local soil moisture critically influences soil biodiversity and spatial community composition, emphasizing the multi-scale drivers of soil biodiversity.</div
Beyond species means – the intraspecific contribution to global wood density variation
No full textInternational audienceWood density is central for estimating vegetation carbon storage and a plant functional trait of great ecological and evolutionary importance. However, the global extent of wood density variation is unclear, especially at the intraspecific level. We assembled the most comprehensive wood density collection to date, including 109 626 records from 16 829 plant species across woody life forms and biomes (GWDD v.2, available here: doi: 10.5281/zenodo.16919509 ). Using the GWDD v.2, we explored the sources of wood density variation within individuals, within species and across environmental gradients. Intraspecific variation accounted for c . 15% of overall wood density variation (SD = 0.068 g cm −3 ). Variance was 50% smaller in sapwood than heartwood, and 30% smaller in branchwood than trunkwood. Individuals in extreme environments (dry, hot and acidic soils) had higher wood density than conspecifics elsewhere (+0.02 g cm −3 , c . 4% of the mean). Intraspecific environmental effects strongly tracked interspecific patterns ( r = 0.83) but were 70–80% smaller and varied considerably among taxa. Individual plant wood density was difficult to predict (root mean square error > 0.08 g cm −3 ; single‐measurement R 2 = 0.59). We recommend (1) systematic sampling of multiple individuals and tissues for local applications, and (2) expanded taxonomic coverage combined with integrative models for robust estimates across ecological scales.La densidad de la madera es fundamental para estimar el almacenamiento de carbono vegetal y constituye un rasgo funcional de gran importancia ecológica y evolutiva. Sin embargo, el alcance global de la variación de la densidad de madera no está claramente descrito, especialmente a nivel intraespecífico. Recopilamos la colección más completa de densidad de madera hasta la fecha, que incluye 109 626 registros de 16 829 especies de plantas leñosas de diversas formas de vida y biomas (GWDD v.2, disponible aquí: doi: 10.5281/zenodo.16919509 ). Utilizando la GWDD v.2, exploramos las fuentes de variación en la densidad de la madera entre individuos y especies, así como a través de gradientes ambientales. La variación intraespecífica representó aproximadamente el 15% de la variación total de la densidad de la madera (SD = 0.068 g cm −3 ). La varianza fue un 50% menor en la albura que en el duramen, y un 30% menor en la madera de ramas que en la del tronco. Los individuos en ambientes extremos (secos, cálidos, suelos ácidos) presentaron una densidad de madera mayor que sus congéneres en otros lugares (+0.02 g cm −3 , ~4% de la media). Los efectos ambientales intraespecíficos siguieron estrechamente los patrones interespecíficos ( r = 0.83), sin embargo, resultaron entre un 70% y un 80% menores y variaron considerablemente entre los taxones. La densidad de madera por individuo fue difícil de predecir (RMSE >0.08 g cm −3 ; R 2 de medición única = 0.59). Recomendamos (1) el muestreo sistemático intraespecífico de múltiples individuos para aplicaciones locales y (2) una cobertura taxonómica ampliada combinada con modelos integradores para obtener estimaciones robustas a través de las escalas ecológicas.La densité du bois est essentielle pour estimer le stockage de carbone de la végétation et constitue un trait fonctionnel d’une grande importance écologique et évolutive. Cependant, l’ampleur de la variation globale de la densité du bois reste mal caractérisée, en particulier au niveau intraspécifique. Nous avons rassemblé la base de données la plus complète à ce jour sur la densité du bois, comprenant 109 626 mesures provenant de 16 829 espèces de plantes ligneuses appartenant à diverses formes de vie et biomes (GWDD v.2, disponible ici: doi: 10.5281/zenodo.16919509 ). À l’aide de la GWDD v.2, nous avons exploré les sources de variation de la densité du bois au sein des individus, au sein des espèces et le long de gradients environnementaux. La variation intraspécifique représentait environ 15% de la variation totale de la densité du bois (SD = 0,068 g cm −3 ). La variance était 50% plus faible dans l’aubier que dans le duramen, et 30% plus faible dans le bois des branches que dans celui du tronc. Les individus vivant dans des environnements extrêmes (secs, chauds, sols acides) présentaient une densité du bois plus élevée que leurs congénères ailleurs (+0,02 g cm −3 , soit ~4% de la moyenne). Les effets environnementaux intraspécifiques reflétaient les tendances interspécifiques ( r = 0,83), mais étaient 70 à 80% plus faibles et variaient considérablement entre taxons. La densité du bois à l’échelle individuelle était difficile à prédire (RMSE >0,08 g cm −3 ; R 2 = 0,59). Nous recommandons (1) un échantillonnage systématique de plusieurs individus et tissus pour les applications locales et (2) un élargissement de la couverture taxonomique combiné à des modèles intégratifs afin d’obtenir des estimations robustes à travers les échelles écologiques