ABSTRACT Forest fires are becoming more intense and frequent, which has serious consequences for animal populations. Rapid assessment of the impact of fires on endangered species is essential for accurately guiding conservation efforts. The impacts of fire can be immediate, such as death from heat or smoke, or delayed, such as injury and habitat degradation. In burnt landscapes, survivors are largely deprived of shelter from extreme weather conditions and predators, as well as food resources and their usual geographical landmarks. However, survivors represent the greatest hope for repopulation. The lack of post‐fire monitoring data on individual behavior and physiology may mislead conservation decisions. Knowing how survivors adapt to degraded post‐fire habitats is critical, although implementing rigorous assessments is particularly challenging, especially for long‐lived species. In the summer of 2021, a forest fire in south‐eastern France devastated 5276 ha of Mediterranean habitats, causing high mortality rates (40% to 60%, depending on vegetation density and fuel availability) and numerous injuries in one of the last populations of the protected Hermann's tortoises ( Testudo hermanni hermanni ). Injured (after veterinary care) and unharmed survivors ( N = 25) were immediately monitored by radio tracking for 2 years. Control individuals ( N = 10) were monitored after the fire on a nearby unburnt control site, allowing a reliable assessment of delayed fire effects. Surprisingly, the survivors did not leave the devastated landscapes. The image of devastated landscapes with survivors apparently wandering over scorched earth is misleading; tortoises experimentally displaced to intact areas rapidly returned to their original ranges, and burnt‐area survivors selected high quality residual microhabitats and maintained body condition and movements comparable to control individuals in unburnt habitats.

Rare and endemic plant populations are particularly vulnerable to global human-induced perturbations. Teucrium polium subsp. purpurascens (Benth.) (S. Puech, 1976) (Lamiaceae) is a rare and endangered plant species restricted to the coastal habitats of the Calanques National Park (southern France). Most populations are found on a continental archipelago located at two kilometres from the mainland. To investigate the interactions of Teucrium polium subsp. purpurascens with its flower visitors, we compared the insect’s richness and abundance foraging on this rare species, as well as its relative attractiveness, with those of a widespread close relative Teucrium flavum (L., 1753). Here, we show a strong dichotomy in floral visitors foraging on the two plant species, T. p. purpurascens being visited by a wide diversity of insects while T. flavum attracted almost exclusively bees. The two plant species also have very distinct guilds of visiting bees, with only nine species in common. Moreover, the plants’ attractiveness strategies are widely dissimilar. Teucrium p. purpurascens offers a large number of highly nectar-concentrated flowers to a guild of small, short-tongued bees, while T. flavum produces a larger quantity of less concentrated nectar for a guild of large, long-tongued bees. The differences between the two species in both attractiveness strategies and flower visitor guilds highlight the need to consider plant-flower visitor interdependencies for the conservation of rare and isolated plant species.

Urban streams are increasingly affected by historical and ongoing industrial pollution. This study examined the distribution and bioaccumulation of metals and metalloids (MM) along the Aygalades stream (Marseille, France), a highly impacted urban watershed. One important finding was the widespread and severe contamination by metals and metalloids (MM) throughout the stream, with concentrations reaching exceptionally high levels. Sediments and soils showed extremely high concentrations of Cu, Pb, As, and Cr, while water showed localized chromium peaks suggesting direct industrial inputs, reflecting both legacy and current contamination sources. A second key feature is the high bioaccumulation observed in various freshwater organisms, particularly in benthic macroalgae Cladophora glomerata, which showed exceptional MM accumulation, especially for Cr and Pb, confirming its value as a biomonitor. Macroinvertebrates such as Baetis rhodanii and Caenis luctuosa also exhibited elevated metal concentrations, suggesting potential exposure to contaminated sediments and other environmental sources, while tolerant crustaceans (Gammarus pulex, Asellus aquaticus) showed comparatively lower concentrations, suggesting differences in metal regulation among taxa. Riparian plants (Rubus ulmifolius, Ficus carica) also accumulated metals, supporting their potential use in phytostabilization. Overall, MM concentrations in biotic compartments generally mirrored spatial contamination patterns observed in abiotic matrices. These findings revealed extensive contamination across environmental compartments and taxa, illustrating the urban stream syndrome and emphasizing the long-term ecological consequences of industrial pollution in urban streams.

In the face of habitat degradation and subsequent species decline, translocation has become a popular management tool to increase persistence of threatened species. Astragalus tragacantha, a rare and endangered thorny cushion shrub mainly occurs, in southeastern France, along degraded coastal habitats, near a large Mediterranean conurbation. Most individuals (88.4% of 4919) are listed inside the French Calanques National Park (CalNP), south of the city of Marseille. Its peri-urban location combines challenges of protection under high anthropogenic pressure. This study was carried out as part of the European LIFE Habitats Calanques project, aiming to restore fragmented coastal habitats and vulnerable plant populations. Our objective was to implement translocations to reduce the extinction risk of A. tragacantha populations. Plantlets were transplanted in the Cal-NP, in seven reinforcement (augmentation) sites and three (re)introduction ones displaying contrasted microhabitats. A subset of plantlets was regularly monitored to look for correlations between survival rates and environmental factors such as soil type, nutrient contents, or herbaceous and rocks cover. After 53 months, the average survival rate of transplanted A. tragacantha was 26%, with high variability between sites. Contrasting effects of environmental factors on plant survival versus final plant size were observed. Indeed, survival rates were higher in rocky microhabitats compared to richer soils. On the latter, plant cushions were bigger, but those habitats were less favorable due to competition with herbaceous plants. This study highlights the need to consider the influence of microhabitat on plant survival, but also plant development and reproduction, when planning the translocation of threatened plants for conservation.

Les colonies d’oiseaux marins nicheurs impactent la physico-chimie des sols ainsi que les communautés végétales sur les îles. Ces écosystèmes insulaires sont caractérisés par des plantes endémiques adaptées aux conditions stressantes (xéricité, salinité, sol superficiel, vent). Plusieurs études ont permis d’évaluer les effets de l’augmentation démographique d’oiseaux marins, mais peu ont réalisé un suivi sur le long terme en prenant en compte leur déclin après explosion démographique. L’objectif de la présente étude (sur 24 ans) a consisté à mesurer les changements physico-chimiques des sols, de la composition des communautés végétales en relation avec la diminution démographique des Goélands leucophées (Larus michahellis Naumann, 1840) sur les archipels insulaires du Frioul et de Riou (Marseille, France). Les enjeux conservatoires de ce contexte insulaire ont été analysés en caractérisant les types fonctionnels des plantes (formes de croissance de Raunkiaer et stratégies de vie de Grime) et en étudiant la variation des plantes à enjeu de conservation, puisque l’apport de nutriments et de polluants, tels que les éléments traces métalliques, via les goélands peut entraîner leur disparition. Pour cela, des analyses de sol (en 1997 et 2021) ainsi que des relevés floristiques (en 1997, 2008 et 2021) ont été réalisés sur 78 placettes permanentes situées sur neuf îles et sur le littoral continental du Parc national des Calanques. Depuis 1997, les teneurs en nitrogène et le pH ont augmenté, alors que le carbone organique ainsi que le rapport C/N ont diminué. En 2021, les mesures des concentrations en éléments traces révèlent des niveaux de contamination relativement faibles sur le continent et les archipels. De 2008 à 2021, les communautés végétales des îles ont été caractérisées par une augmentation du nombre de plantes rudérales. Le déclin des effectifs de Goélands leucophées n’a pas engendré de diminution des plantes tolérantes aux perturbations ni d’augmentation très significative de la flore à enjeu de conservation, mais a entraîné une augmentation des chamaephytes et du recouvrement total de la strate herbacée. Nos résultats suggèrent donc une rémanence des altérations des paramètres des sols ainsi que des communautés végétales toujours rudéralisées. Cependant, une résilience s’opère en termes de recouvrement de la strate herbacée lorsque la pression des goélands diminue.

Urbanisation is a growing phenomenon causing the decline of wild bees globally. However, bees manage to persist in the urban environment thanks to islands of vegetation in public parks and private gardens. While we are beginning to comprehend the impact of urbanisation on bees’ diversity and abundance, our understanding of its impact on the functional diversity of wild bees is limited. Here, we employ an integrative approach to investigate the response of wild bees to urbanisation at the community, species, and individual levels. To do so, we sampled wild bees in 24 public parks along an urbanisation gradient in the Mediterranean city of Marseille. We found that species richness and abundance decreased in more urbanised areas, but increased in larger city parks. Moreover, we observed larger individuals within species, but not larger species, in larger city parks, suggesting that park size plays a crucial role for urban bees at the intraspecific level. Interestingly, brightly coloured species were found in parks surrounded by a large amount of impervious surface, highlighting the importance of colour traits in the response to environmental changes. Finally, we showed that larger species, but not larger individuals, were also more colourful. In summary, our study not only confirmed that urbanisation negatively impacts community-level traits, but that it also filters species based on coloration and affects individuals’ body size. This improves our understanding of the functional response of wild bees to urbanisation. We suggest that increasing park size may partly compensate for the negative effects of urbanisation on wild bees.

Beyond ecological and health impacts, invasive alien plant species can generate indirect and direct costs, notably through reduced agricultural yields, restoration, and management of the invaded environment. Acacia dealbata and Ailanthus altissima are invasive plant species that cause particularly significant damage to the railway network in the Mediterranean area. The allelopathic properties of Mediterranean plant species could be used as nature-based solutions to slow down the spread of such invasive plant species along railway borders. In this context, a mesocosm experiment was set-up: (i) to test the potential allelopathic effects of Cistus ladanifer, Cistus albidus, and Cotinus coggygria leaf aqueous extracts on seed germination and seedling growth of A. dealbata and A. altissima; (ii) to evaluate whether these effects depend on the extract dose; and finally, (iii) to estimate whether these effects are modified by soil amendment. Leaf aqueous extracts of the three native plant species showed negative effects on both seed germination and seedling growth of the two invasive species. Our results show that the presence of allelochemicals induces a delay in seed germination (e.g., A. dealbata germination lasted up to 269% longer in the presence of high-dose leaf aqueous extracts of C. coggygria), which can lead to a decrease in individual recruitment. They also highlight a decrease in seedling growth (e.g., high-dose C. coggygria leaf aqueous extracts induced a 26% decrease in A. dealbata radicle growth), which can alter the competitiveness of invasive species for resource access. Our results also highlight that compost addition limits the inhibitory effect of native Mediterranean plants on the germination of invasive alien plants, suggesting that soil organic matter content can counteract allelopathic effects on invasive alien plants. Thus, our findings revealed that the allelopathic potential of certain Mediterranean plant species could be a useful tool to manage invasive plant species.

L’étude des plantes vasculaires introduites par les humains hors de leur aire de répartition naturelle a généré une terminologie très prolifique qui est souvent devenue absconse et inutilement complexe. Durant les dernières décennies, l’écologie des invasions a cherché, au contraire, à replacer les processus d’introduction, de naturalisation et d’invasion des taxons au sein d’un cadre théorique unifié. Dès lors, la terminologie qui décrit le statut d’un taxon le long de la séquence introduction-naturalisation-invasion peut être clarifiée et simplifiée. Dans le cadre du projet d’inventaire des plantes vasculaires exogènes de France hexagonale, nous proposons de moderniser et d’harmoniser la terminologie française avec celle de la littérature internationale en se fondant, autant que possible, sur des processus écologiques. Ce travail a conduit à approfondir des notions telles que néotaxon, ainsi qu’à préciser le sens de « plante invasive » et de « plante exotique envahissante » en fonction des abondances locale (au niveau d’une population) et régionale (au niveau d’un territoire) et de la prise en compte ou non de leurs impacts. Une terminologie clarifiée devrait aussi permettre aux gestionnaires de mieux cibler et optimiser leurs stratégies de gestion.

Urban streams display consistent ecological symptoms that commonly express degraded biological, physical, and chemical conditions: the urban stream syndrome (USS). Changes linked to the USS result in consistent declines in the abundance and richness of algae, invertebrates, and riparian vegetation. In this paper, we assessed the impacts of extreme ionic pollution from an industrial effluent in an urban stream. We studied the community composition of benthic algae and benthic invertebrates and the indicator traits of riparian vegetation. The dominant pool of benthic algae, benthic invertebrates and riparian species were considered as euryece. However, ionic pollution impacted these three biotic compartments' communities, disrupting these tolerant species assemblages. Indeed, after the effluent, we observed the higher occurrence of conductivity-tolerant benthic taxa, like Nitzschia palea or Potamopyrgus antipodarum and plant species reflecting nitrogen and salt contents in soils. Providing insights into organisms’ responses and resistance to heavy ionic pollution, this study sheds light on how industrial environmental perturbations could alter the ecology of freshwater aquatic biodiversity and riparian vegetation.

Seabird colonies have a strong influence on both the physical and chemical soil parameters and plant communities of the islands where they settle to nest. Scientists have studied the effects of the demographic explosion of seabird pop- ulations, but few have explored the long-term effects when the colonies were in decline. The aim of this study was to investigate diachronic changes over a 24 year period of soil parameters, floristic composition and plant functionnal types (Raunkiaer growth forms and Grime life strategies) up to the decrease of the number of nesting yellow-legged gulls (Larus michahellis Naumann, 1840) on Mediterranean islands. We used 78 permanent plots to survey the vegeta- tion and the soil parameters on 9 islands and one mainland area within the Calanques National Park (south east of France), for three periods (i.e., 1997, 2008, 2021). Since 1997, the increase of nesting gulls has caused a nitrogen and pH increase and organic carbon and C/N ratio de- crease, although the values were still higher than mainland plots without nesting gulls. This has led to changes in plant species composition e.g., higher values of N favouring the development of ruderal plant species, still present in high frequency in 2021. Furthermore, plant species highly tolerant to disturbances (i.e., R Grime strategy) in harsh environ- ments were still favoured even after the decline of gull abundance. However, both the frequency of the chamaephytes and the vegetation cover has increased with the decline of gull colony. In 2021, measures of trace elements' concentra- tions and calculation of pollution load index (Cu, Pb and Zn) reveals relatively low multi-contamination levels on the mainland and the archipelagos.On naturally oligotrophic and semi-arid Mediterranean islands, gull colonies induce a persistent alteration in soil char- acteristics that still influences plant communities (composition and functional types), 11 years after the decline in bird abundance.

Due to the widespread use of pesticides and the lack of floral resources in many agricultural landscapes, beekeepers have moved numerous honey bee colonies in protected areas which could shelter an important diversity of wild bees. Here, we investigated the seasonal dynamics of the competition between honey bees and wild bees through a two‐year study of plant–bee networks in a Mediterranean protected area. We recorded the visitation rates of four bee groups: honey bees, small wild bees, large wild bees and bumblebees. Our study reveals that the competition for floral resources induced by honey bees is especially strong during the early spring and then decreases along the season for all groups of wild bees. We observed a competitive exclusion of all groups of wild bees illustrated by an avoidance of well‐flowered plant species in presence of honey bees. As a consequence, we detected a rewiring of large and small bee floral preferences linked to the presence of honey bees. In presence of honey bees, Rosmarinus officinalis and Cistus albidus were significantly less visited by large bees. This study underlines the need to mitigate the establishment of numerous honey bee colonies in protected areas as honey bees could strongly affect the foraging activity of wild bees.

Face à la dégradation anthropique des habitats littoraux du Parc national des Calanques, le projet européen LIFE Habitats Calanques (LIFE16 NAT/FR/000593) a pour objectif d’entreprendre des actions de protection et de restauration écologique à grande échelle. Parmi ces habitats, la phrygane (code Natura 2000 : 5410) représente un exemple typique d’une situation littorale contrainte par une forte anthropisation et des conditions climatiques drastiques. Cet habitat est structuré par l’Astragale de Marseille (Astragalus tragacantha L.), une espèce végétale rare et protégée dont ses populations sont vulnérables, notamment à la fragmentation et aux embruns pollués. Cependant, cette espèce tolère des concentrations édaphiques élevées d’éléments traces métalliques et métalloïdes (ETMM) issus d’activités industrielles passées. Des études précédentes ont caractérisé des symbioses racinaires typiques de A. tragacantha (endomycorhizes à arbuscules et nodules à rhizobium) pouvant expliquer sa capacité à tolérer les stress hydrique et nutritif ainsi que la contamination des sols. Dans la présente étude, sur la base d’une carte d’occupation des sols, la modélisation de la probabilité de présence d’A. tragacantha selon l’altitude, la pente et l’exposition a permis d’identifier plusieurs zones favorables à son développement. Sur ces zones, la contamination en ETMM a été analysée. Ces travaux complémentaires permettent d’envisager la restauration des populations d’A. tragacantha par transplantation de plantules, soit en renforcement des populations existantes, soit en les introduisant dans de nouveaux sites favorables afin d’augmenter la connectivité entre populations. Cette opération de restauration permettra également de favoriser la phytostabilisation des ETMM et participera à la re-fonctionnalisation des sols contaminés.

The importance of insects for global food crop production is starting to be well-known but the level of dependence on insects is less referenced, especially for some aromatic crops. Fennel (Foeniculum vulgare, Mill.) is an aromatic mass-flowering crop cultivated in the south of France for its essential oil that contains anethole. This compound is of food and economical interest because of its anise flavour, which is used to elaborate anise drinks. Here, we have characterized the dependence of fennel on insect pollination. We used four controlled pollination treatments to compare the reproductive success (fruit initiation rate, fruit weight), and the fennel yield (fruit weight and amount of anethole per hectare) between insect pollinated flowers and bagged flowers. We also checked the ability of reproduction by self-pollination in this species, and the existence of a reproductive limitation linked to insect activity. We have shown that pollination without insects leads to reproductive failure in fennel. At the field level, insect pollination is fundamental to improve the fruit initiation rate, the fruit weight and the amount of anethole per hectare leading to an estimated 86 % dependence of fennel on insect pollination. Finally, we showed no reproductive limitation with the current state of insect activity. This study adds new evidence of the importance of insects in agroecosystems to sustain food production.

Nectar is a key resource for numerous insects. Despite its importance, nectar productivity has mainly been assessed using one sampling method, in which the volume of nectar produced by a flower is measured after 24 h of isolation from insects ('measured 24 h volume' hereafter). This method assumes that nectar removal by flower-visiting insects does not affect nectar productivity. Hence, a linearity in the nectar production dynamic is assumed. The effect of nectar removal could lead to an actual volume of nectar produced per flower over 24 h being higher or lower than the measured 24 h volume. Whether the nectar productivity is influenced by insect activity still therefore needs to be assessed. In a field experiment, we estimated the nectar production dynamics of lavender (Lavandula hybrida) and fennel (Foeniculum vulgare) flowers and tested whether they met the linearity assumption. Then, we developed a simulation model to identify how different scenarios of insect foraging activity: nectar removal rate (average and maximum), and flower-selection strategies (random selection or rewarding flower selection) alter the estimated 24 h volume of nectar for both crops ('estimated 24 h volume' hereafter). Finally, we tested whether the estimated 24 h volume differed from the measured 24 h volume for both crops. Lavender and fennel showed equal measured 24 h volume of nectar but the produced nectar volume over 6 h suggested that a flower of lavender was more productive than a flower of fennel. Both nectar production dynamics did not meet the assumption of linearity. The simulation models showed that the estimated 24 h volume increased with maximum nectar removal rate for lavender, and the opposite was found for fennel. Rewarding selection always increased the estimated 24 h volume for fennel while for lavender a positive effect was detected at average rate of nectar removal. We found that the estimated 24 h volume was always greater than the measured 24 h volume. Our model demonstrated that the effect of insect foraging activity on flower's nectar productivity should be considered while estimating the resources produced by plants. As an alternative, measures of produced nectar volume in short time spans may be compared with the measured 24 h volume to check the reliability of this widespread method. Read the free Plain Language Summary for this article on the Journal blog.

The importance of insects for global food crop production is starting to be well-known but the level of dependence on insects is less referenced, especially for some aromatic crops. Fennel ( Foeniculum vulgare ) is an aromatic mass-flowering crop cultivated in the southern of France for its essential oil that contains trans -anethole of food and economical particular interest since it is used to elaborate anise drinks. Here, we have characterized the dependence of fennel on insect pollination. We used four controlled pollination treatments to compare the reproductive success (fruit initiation rate, fruit weight), and the fennel yield (weight of the fruits and amount of trans -anethole at the crop level) between insect pollinated flowers and bagged flowers. We also checked the ability of reproduction by autogamy in this species, and the existence of a reproductive limitation linked to insect activity. We have shown that pollination without insect leads to reproductive failure in fennel which is not an autogamous plant species. At the crop level, insect pollination is fundamental to improve the fruit initiation rate, the weight of the fruits and the amount of trans -anethole leading to an 92% dependence of fennel on insect pollination. Finally, we showed no reproductive limitation with the current state of insect activity. We are thus providing interesting clues to managers and producers to support the production of fennel crops, showing once again that insects are essential to sustain global food production.

Agricultural landscapes are more and more characterized by intensification and habitat losses. Landscape composition and configuration are known to mediate insect abundance and richness. In the context of global insect decline, and despite 75% of crops being under insect’s dependence, there is still a gap of knowledge about the link between pollinators and aromatic crops. Fennel (Foeniculum vulgare) is an aromatic plant cultivated in South of France, for its essential oil which is of great economic interest. Using pan-traps, we investigated the influence of the surrounding habitats at landscape scale (semi-natural habitat proportion and vicinity, landscape configuration) and local scale agricultural practices (insecticides and patch size) on fennel-flower-visitor abundance and richness and their subsequent impact on fennel essential oil yield. We found that fennel may to be a generalist plant species. We did not find any effect of intense local management practices on insect abundance and richness. Landscape configuration and the proximity to semi-natural habitat were the main drivers of flying insect’s family richness. This richness positively influenced fennel essential oil yield. Maintaining a complex configuration of patches at the landscape scale are important to sustain insect diversity and crop yield.

Question Species of the genusCarpobrotus, or ice plant, are succulent mat-forming perennial herbs often introduced for soil stabilization. They are common in coastal environments and may thus threaten island biodiversity. While their effects are well known on soils, plant communities and associated fauna, the effects ofCarpobrotuscontrol on vegetation recovery are poorly documented. The aim of the paper is to describe plant community trajectories afterCarpobrotusremoval. Location Bagaud: a 58-ha Mediterranean island, southern France. Methods Carpobrotusand its litter were removed in 2011-2012. Follow-up controls of germinations and resprouts were carried out from then on. Plant communities were surveyed every year two years before and seven years afterCarpobrotusremoval: on two ca. 0.5-ha sites (one coastal and one inland) and in three native plant communities used as potential references. Differences in resprouts, vegetation parameters, and Bray-Curtis similarity indices between years were tested. Plant community dynamics was studied through a non-metric multidimensional scaling and two recovery indices. Results The removal ofCarpobrotusand its litter led to the recovery of diverse native plant communities. To preventCarpobrotusreturn and ensure success, follow-up controls were necessary for a period of at least seven years, but the amount of work decreased with time. The plant community recovering on the coastal site quickly reached a composition and structure similar to that of non-invaded coastal vegetation, although some slow-growing native species remain underrepresented (e.g.,Crithmum maritimumandLimonium pseudominutum). The plant community recovering on the inland site was still very different from the surrounding matorral vegetation because of its slow colonization dynamics, particularly in the presence of competitive herbaceous species. Conclusion Both sites now provide diverse native plant communities with a more diversified composition and structure (plant heights, litter, bare ground patches) than the plant communities which used to be associated withCarpobrotusmats.