Environmental heterogeneity in forest understories creates microhabitat niches that differ both spatially and temporally in light intensity and temperature. Do animal communities segregate in relation to these niche dimensions, and can this be explained by functional traits? Answering these questions is particularly important for insect pollinators, as they play a critical role in maintaining flowering plant biodiversity. Bumblebees are essential pollinators of high altitude/latitude ecosystems and are particularly sensitive to climate change. In early spring, they forage on bilberry, a keystone species in heterogeneous habitats – hemi‐boreal forests. We capitalised on these conditions to study a species‐specific selection of foraging niches in relation to abiotic conditions. We combined full‐day monitoring of bumblebee communities foraging in bilberry‐dominated forests with joint species distribution modelling, which showed that temperature conditioned species occurrence, while light intensity explained species abundance. The inclusion of functional traits did not improve the overall explanatory and predictive power of the models. Our results suggest that temperature acts as a first filter of the local species pool and that species, once present, partition along a light intensity gradient. This study confirms and extends upon previous findings that microhabitat partitioning may act as a mechanism underpinning bumblebee coexistence. It highlights the importance of focusing on micro‐scales when studying how species interact with their environment, as this could, for example, help improve our ability to predict the consequences of global changes.

Intensification of forest management to increase production of biomass has resulted in considerable habitat degradation with negative impacts on insect biodiversity, including beneficial insect groups such as pollinators. Yet, little is known about how reliant forest understory plants, such as bilberry (Vaccinium myrtillus), are on insect pollinators for reproduction. Here, we quantified the structure of the bilberry flower visitor community, compared the pollination effectiveness of the most common pollinators, and experimentally quantified bilberry pollination dependency. The bilberry pollinator community was comprised of several bee and hoverfly taxa. Bumblebees were the most important pollinators due to their high abundance and pollination effectiveness. Other bees, in particular, Andrena spp., and to a smaller extent, hoverflies, were also effective pollinators. Furthermore, bilberry was strongly pollen-limited, with only 40% of open-pollinated flowers setting fruit. Bilberry supports a diverse flower visitor community within hemi-boreal forests, for which it is highly dependent for reproduction. Given the ecological and cultural value of bilberry, the importance of insect pollinators for understory plants should be considered within forest management strategies.

While functional traits like body size have been extensively linked to species distributions, the influence of sensory traits on species' responses to environmental changes remains underexplored. Particularly, the relationship between light sensitivity and niche segregation across different distributional extents - local habitat conditions and across entire landscapes - remains unclear. In this study, we examined bumblebee communities monitored across Norway on grassland and forest habitats within landscapes varying in forest cover within 1 km radii. We investigated whether the eye parameter - a visual trait measuring the trade-off between light sensitivity (high values) and visual resolution (low values) - was associated with local habitat types and the forest cover at the landscape scale. Additionally, we combined bumblebee-plant interactions with a plant trait, to determine if bumblebee light sensitivity correlated with the shade tolerance of the plants they foraged on. Our findings showed that bumblebee species with high eye parameters were more common and abundant in forest habitats and areas with greater forest cover, while species with low eye parameters showed the opposite trend. This pattern was also reflected at the community level, as indicated by the community-weighted mean of the eye parameter which increased with forest cover and was higher in forest habitats. Furthermore, bumblebees with higher eye parameters tended to forage on plants with greater shade tolerance. These results suggest that visual adaptations for light sensitivity contribute to shaping bumblebee species distributions across different scales. Overall, our study underscores the importance of pollinator vision in understanding species niches, in relation to habitat use and foraging behaviour. By relating pollinator visual abilities to plant niches for the first time, this study provides an important basis for future modelling of plant-pollinator interactions and targeted conservation measures for both plants and pollinators in forested landscapes. ### Competing Interest Statement The authors have declared no competing interest.

Local coexistence of bees has been explained by flower resource partitioning, but coexisting bumblebee species often have strongly overlapping diets. We investigated if light microhabitat niche separation, underpinned by visual traits, could serve as an alternative mechanism underlying local coexistence of bumblebee species. To this end, we focused on a homogeneous flower resource-bilberry-in a heterogeneous light environment-hemi-boreal forests. We found that bumblebee communities segregated along a gradient of light intensity. The community-weighted mean of the eye parameter-a metric measuring the compromise between light sensitivity and visual resolution-decreased with light intensity, showing a higher investment in light sensitivity of communities observed in darker conditions. This pattern was consistent at the species level. In general, species with higher eye parameter (larger investment in light sensitivity) foraged in dimmer light than those with a lower eye parameter (higher investment in visual resolution). Moreover, species realized niche optimum was linearly related to their eye parameter. These results suggest microhabitat niche partitioning to be a potential mechanism underpinning bumblebee species coexistence. This study highlights the importance of considering sensory traits when studying pollinator habitat use and their ability to cope with changing environments.

Pollination is a critical ecosystem service given its essential role in sustaining food production, while pollinating insects are declining worldwide. Pollination capacity can be estimated through direct indicators characterising pollinator communities. Pollinators need feeding and nesting resources, so their presence can also be estimated through indirect indicators characterising these resources at plot and landscape scales. In this study, we aimed to identify the subset of resource indicators accounting for pollination capacity in orchards by relating insect presence to the most relevant environmental variables for managing pollinator presence. In 31 orchards of the Grenoble region (France) we measured direct indicators of pollinator abundance and richness at plot scale. Simultaneously we quantified indirect indicators of landscape and plot scale feeding and nesting resources. We selected indicators significantly correlated with insect presence using simple linear models between resource indicators and measures of insect taxonomic richness and abundance. Multiple linear regressions including significant resource indicators at both plot and landscape scales showed that landscape composition and presence of beehives explained between 19 and 63 % of the observed variance of pollinator community indicators. Total pollinator abundance decreased with distance to the closest grassland patch and increased with abundance of beehives. Pollinator richness increased with grassland cover within a 3 km radius. Domestic honeybee abundance increased with beehives located both in the plot and the landscape, and decreased with isolation from the closest grassland patch. Wild hymenopteran abundance increased with grassland cover within 3 km and forest cover at 500 m. Dipteran abundance increased when beehives were located only in the landscape. This study highlights the prevalent role of landscape-scale resources for pollinator communities over in-field flower resources. Thus, in order to favour pollinators, management should focus mainly on the landscape scale, necessitating cooperation between farmers. However, as resource indicators explained less than half of the observed variance for most community variables, inferring pollinator community characteristics from specific environmental variables remains uncertain. Further work could explore how orchard management practices influence our conclusions.

Observed declines in pollinator populations due to human pressures is of critical concern because pollination is an essential regulating ecosystem service (ES). Pollination has a major role in human food production and in maintaining flowering plant diversity. Estimating the pollination ES and its trends is thus essential for informing policy and management. However, the pollination ES remains poorly defined in practice as it is a polysemic term. In practice it is considered as: the ecosystem capacity to support pollination, the social demand for pollination or the actual pollination flow, which is the match between capacity and demand. Its quantification is complicated by the coexistence of numerous indicators. In this paper, we aimed to disentangle the diversity of definitions of the pollination service along with their associated indicators and field methods in the ecosystem service literature. From 131 reviewed papers, most studies were under temperate climate with a focus on hymenopteran pollinators, overlooking the importance of hoverflies and other dipteran pollinators. We identified four main pollination ES definitions that can be separated in two categories: (1) pollinator presence and pollen transfer, which are related to the capacity of the pollination ES; and (2) pollination success and production of fruits or seeds for human consumption, which are related to the flow of the pollination ES. Importantly, when quantified simultaneously pollination capacity and flow showed varying levels of congruence. Half of the reported relationships were congruent, but almost as many were neutral. Direct indicators of the two definitional categories characterised the respective actors of the pollination function. Studies of pollination capacity characterised pollinating agents (pollinator communities), while pollination flow studies described seeds and/or fruits produced from animal pollination. Both pollination capacity definitions share insect observations and captures as most frequent methods (70% of analysed studies), with a prevalence of indicators of pollinator diversity and abundance. Pollination flow estimation methods mainly describe the amount (number, weight) and quality of seeds/fruits. Pollinators depend on availability of feeding and nesting resources for their survival, and on their ability to reach them within landscapes. Thus, common indirect indicators of pollination are environmental variables related to semi-natural habitats and flower resources. We end this review with guidelines for relevant choices by ecosystem services scholars and practitioners of indicators and methods according to study questions and constraints (technical, financial, time and skills). Further investigations will be necessary to disentangle pollination capacity and flow relationships.

Carbon sequestration is an essential ecosystem service (ES) for climate change mitigation. For reasons of simplicity this ES is often quantified considering carbon storage in four carbon pools: aboveground biomass, belowground biomass, dead organic matter and soil organic carbon. Indicators of these four pools are estimated by modelling, reference values, or field methods and data processing of different complexity levels which requires comparing estimations. In order to facilitate the assessment of carbon pools, e.g. in environmental impact assessment, a fast, reliable and easily applicable method is required. First, using a systematic literature review we identified frequently used field methods for estimating carbon pools for forests and grasslands, two ecosystems playing a key role in global climate regulation. Second, from this review we developed field methods for indicators of each carbon pool aboveground biomass, belowground biomass, soil organic carbon and dead organic matter in both ecosystem types. We applied these methods in a set of forest and grassland plots in the Grenoble region (France) and asked i) how comparable and consistent are alternative methods for each carbon pool? ii) what is the variability of estimates between these methods? and iii) which level of simplicity has an acceptable level of uncertainty? Thereby, we conducted for the first time method comparisons for all four carbon pools. We based our method comparisons on the quality of the linear relationships between methods and their level of accuracy relatively to the chosen reference methods (the method assumed to be the closest to the actual carbon stock). For most carbon pools e.g. aboveground biomass and soil organic carbon, both major carbon stocks selected alternative methods were comparable and consistent with the reference method. Third, we built on these results to suggest easy and quick field methods for each carbon pool in each ecosystem type with accuracy levels between 10 and 20%. We provide guidelines together with associated uncertainty levels to scientists and practitioners aiming to estimate the ecosystem service of global climate regulation from carbon stocks in terrestrial ecosystems. The guidelines also allow adjusting method selection to human, knowledge and financial resources available in the study context.

Plans de gestion et études d'impact devraient dorénavant inclure les services écosystémiques (SE). Face au changement climatique, la régulation du climat global par le stockage de carbone par les écosystèmes est un SE au cœur des préoccupations. C'est un enjeu de la préservation et de la restauration des zones humides (ZH), écosystèmes susceptibles de stocker des quantités importantes de carbone, en particulier dans leur sol. Nous avons étudié 24 parcelles de ZH afin de déterminer par un modèle « d'états-et-transitions » si des actions de gestion permettraient d'agir sur leur stock de carbone. Les ZH forestières stockaient deux fois plus de carbone que les ZH herbacées. Cette différence repose essentiellement sur la biomasse aérienne. En effet, le stock de carbone organique du sol ne diffère pas entre les états considérés et apparait indépendant de la végétation. Cette étude souligne l'importance du sol des ZH pour la régulation du climat global (> 50% du stock de carbone pour les trois états) et la difficulté à agir sur ce compartiment complexe. Elle met en avant l'utilité des modèles d'états-et-transitions pour projeter l'effet d'actions de gestion sur des SE. Cette approche pourrait être appliquée dans le cadre de la séquence « Eviter, Réduire, Compenser ».

"Beauty is bought by judgment of the eye" (Shakespeare, Love's Labour's Lost), but the bodily features governing this critical biological choice are still debated. Eye movement studies have demonstrated that males sample coarse body regions expanding from the face, the breasts and the midriff, while making female attractiveness judgements with natural vision. However, the visual system ubiquitously extracts diagnostic extra-foveal information in natural conditions, thus the visual information actually used by men is still unknown. We thus used a parametric gaze-contingent design while males rated attractiveness of female front- and back-view bodies. Males used extra-foveal information when available. Critically, when bodily features were only visible through restricted apertures, fixations strongly shifted to the hips, to potentially extract hip-width and curvature, then the breast and face. Our hierarchical mapping suggests that the visual system primary uses hip information to compute the waist-to-hip ratio and the body mass index, the crucial factors in determining sexual attractiveness and mate selection.