Nora Khelidj

Shared flowers can facilitate pathogen transmission between managed honey bees and wild bees, yet this process remains poorly understood in ecosystems undergoing rapid environmental change. Using a glacier foreland in Switzerland, we present the first study on how glacier retreat stages and bee life‐history traits influence pathogen occurrence across honey bees and wild bees. We screened the deformed wing (DWV), acute bee paralysis (ABPV), chronic bee paralysis (CBPV) viruses, the microsporidium Nosema ceranae , and the trypanosomatid Lotmaria passim . While all screened pathogens were detected in honey bees, only N. ceranae and DWV occurred in wild bees, though DWV strains differed between hosts (A in wild bees, B in honey bees). This clear segregation of pathogen communities between honey bees and wild bees is likely explained by the different floral resources used bythe two bee groups, overall forming a moderately specialised and not nested network with honey bees especially targeting few plant species rarely visited by wild bees. Sociality and nesting habits did not explain pathogen loads, whereas glacier retreat stage significantly influenced DWV abundance, with higher loads in older successional stages. This case study provides a fascinating example of how the use of floral resources by honey bees and wild bees, alongside the landscape changes induced by glacier retreat, can greatly influence pathogen transmission dynamics.

As glaciers retreat worldwide, newly exposed terrains are rapidly colonized by plants and their associated animal communities. Although plant–animal interactions are key for biodiversity maintenance and ecosystem functioning, the ecological processes underlying the assembly and development of trophic interactions over space-time remain poorly understood. Here, we investigated the trophic niche structure of plant–arthropod interactions along a 140-year primary succession at Mont Miné glacier foreland (Switzerland). Using arthropod gut-content DNA metabarcoding, we reconstructed trophic interactions at the food web level, revealing numerous previously undetected links among 284 arthropod taxa feeding on 263 plant taxa. Trophic niche overlap among arthropods increased following glacier retreat, indicating decreasing resource partitioning and suggesting increased resource competition. Trophic niche breadth became narrower and diet species richness declined, indicating increased trophic specialization. Notably, changes in trophic interactions occurred more rapidly than shifts in species diversity or community composition of plants and arthropods. These results demonstrate that glacier retreat reorganizes trophic networks beyond simple species turnover, reshaping biotic interactions during ecosystem development. Our findings highlight trophic interactions as sensitive indicators of biodiversity change and suggest that the stability of emerging food webs may be strongly affected as glaciers vanish worldwide.

Societal Impact Statement: Herbaria worldwide hold centuries of plant data that are key to understanding and protecting biodiversity; however, even with increased digital access, differences in plant naming systems make it difficult to compare records. We developed a semi‐automated workflow that standardises species names and organises herbaria records from multiple institutions into a single, curated digital collection. Applying our workflow to the digitised flora of Greenland, we improved the accuracy of diversity estimates and highlighted tentative species previously unrecognised in Greenland. Our resulting open‐access resource opens new doors for large‐scale studies on Arctic plant diversity over space and time. Summary: International efforts in digitisation and online data sharing of herbarium specimens are revolutionising our ability to obtain big data from herbarium collections. The herbaria of the future will be global, digitally interlinked, open‐access resources that will stimulate large‐scale and novel science to directly address our current biodiversity and climate crises. However, taxonomic changes and errors can result in inconsistencies when amalgamating specimen metadata, that compromise the assignment of occurrence records to correct species and the subsequent interpretation of patterns in biodiversity. We present a novel workflow to mass‐curate digital specimens. By employing existing digital taxonomic backbones, we aggregate specimen names by their accepted name and flag remaining cases for manual review. We then validate names using site‐specific floras, balancing automation with taxonomic expert‐based curation. Applying our workflow to the vascular plants of Greenland, we harmonised 177,138 digitised herbarium specimens and observations from 88 data providers from the Global Biodiversity Information Facility (GBIF). The harmonised metacollection of the Greenland flora contains 753 plant species. Our workflow increases the number of species known from Greenland compared to other currently available species checklists and increases the mean number of occurrences per accepted name by 48. Our workflow illustrates the nomenclature data integration required to create a global, universally accessible digital herbarium and shows how previous obstacles to database curation can be overcome through a combination of automation and expert curation. For the Greenland flora, our approach provides a new species list and a curated metacollection of occurrence data.

Alpine environments are among the most vulnerable ecosystems to climate change, with glacier retreat rapidly altering plant communities, biodiversity, and ecosystem functions. However, the socio‐economic consequences of these biodiversity changes remain largely unexplored. Understanding Nature's Contributions to People (NCP) provides a valuable framework for assessing biodiversity's role in human well‐being. While NCP has typically been studied at the landscape level, we focus on species‐specific contributions of plants to highlight the importance of glacial biodiversity for people. Our novel concept of Plants' Contributions to People (PCP) provides insights into the ecological, social, and economic significance of plant biodiversity and offers a practical approach for guiding conservation efforts and policy decisions. We surveyed 99 plant species in four glacier environments in the Italian Alps; one glacier (Trobio) underwent a complete extinction in 2023 while another glacier (Amola) has a widespread surface debris cover and is proximate to extinction. We then grouped plant species into early, intermediate, and late depending on their successional stages, and then linked plants to 13 different PCP based on extensive literature research. By comparing present and projected future scenarios, we assessed the absolute and relative changes in PCP under glacier extinction. Our results show that changes in PCP are primarily driven by declining plant species richness. Most affected PCP are associated with air quality, soil health, and nutrient regulation, which decrease by sevenfold on average across plant species. Whereas natural hazards regulation showed no significant variation, association with pest and disease increases especially for late species. While future plant communities may provide PCP that are qualitatively similar to present‐day communities, the volume of species‐specific contributions would decrease due to biodiversity loss associated with glacier extinction. Our results provide the first evidence of PCP shift toward erosion following a decrease in plant species richness. This case study demonstrates that PCP is a valuable tool for assessing the ecological and socio‐economic consequences of biodiversity change, helping raise awareness of the biodiversity crisis and inform conservation actions aimed at sustaining ecosystem functions in a rapidly changing world.

The retreat of glaciers due to climate change is reshaping mountain landscapes and biodiversity. While previous research has documented vegetation succession after glacier retreat, our understanding of functional diversity dynamics is still limited. In this case study, we address the effects of glacier retreat on plant functional diversity by integrating plant traits with ecological indicator values across a 140-year chronosequence in a subalpine glacier landscape. We reveal that functional richness and functional dispersion decrease with glacier retreat, while functional evenness and functional divergence increase, suggesting a shift towards more specialized and competitive communities. Our findings highlight the critical role of ecological factors related to soil moisture, soil nutrients, and light availability in shaping plant community dynamics. The integrative approach of this case study provides novel insights into the potential response of alpine plant communities to climate change, offering a deeper understanding of how to predict and anticipate the effects of glacier extinction on biodiversity in rapidly changing environments.

Summary: International efforts to digitise herbarium specimens provide the building blocks for a global digital herbarium. However, taxonomic changes and errors can result in inconsistencies when amalgamating specimen metadata, that compromise the assignment of occurrence records to correct taxa, and the subsequent interpretation of patterns in biodiversity. We present a novel workflow to mass-curate digital specimens. By employing existing digital taxonomic backbones, we aggregate specimen names by their accepted name and flag remaining cases for manual review. We then validate names using site-specific floras, balancing automation with taxonomic expert-based curation. Applying our workflow to the vascular plants of Greenland, we harmonised 175,266 digitised herbarium specimens and observations from 92 data providers from the Global Biodiversity Information Facility (GBIF). The harmonised metacollection for the Greenland flora contains 780 plant species. Our workflow increases the number of species known from Greenland compared to other currently available species checklists and increases the mean number of occurrences per species by 42.6. Our workflow illustrates the integration required in order to create a global, universally accessible digital herbarium, and shows how previous obstacles to database curation can be overcome through a combination of automation and expert curation. From the specific perspective of the Greenland flora, our approach arrives at a new checklist of taxa, a new curated metacollection of occurrence data, and revised estimates of plant richness. The list of taxa and their prevalence allow a new basis for biodiversity assessment and conservation planning. Societal Impact Statement: Digitising plant collections has allowed for data to be aggregated across multiple collections, forming a single harmonised resource of unprecedented scale. This resource is only accurate once the database names are assigned to one accepted name per species. We established a semi-automated workflow for processing plant name data, leveraging taxonomic backbones and employing taxonomic expertise at key stages. Applying our workflow to the flora of Greenland, we developed a curated checklist of 780 species, capturing greater species richness than previously published, while also curating 175,266 plant records. Our findings redefine our knowledge of Greenlandic plant diversity, while harmonising a vast digital collection for further research.

Questions: The disappearance of glaciers threatens biodiversity and the functioning of ecosystems. Yet, questions remain about the response of functional diversity to glacier retreat. How does glacier retreat influence functional diversity? How does glacier retreat influence the relationship between taxonomic diversity and functional diversity? How does glacier retreat impact community mean and intraspecific trait variability (ITV) of key functional traits?Location: Four retreating glacier ecosystems in the Italian Alps. Plant communities spanning 0 to ca 5000 years on average after glacier retreat, including a scenario of glacier extinction.Methods: We quantified functional diversity analyzing twelve plant traits associated to carbon and nitrogen cycling, resource allocation, and reproduction of 117 plant species. We addressed how functional diversity changes with glacier retreat and taxonomic diversity (i.e., plant species richness).Results: Plant functional diversity decreases with glacier extinction while increasing with species richness. The positive relationship between taxonomic and functional diversity becomes flatter, that is, less important, with glacier retreat. We document sharp changes in functional niche position and breadth with glacier retreat. Key functional traits associated with carbon cycling and resource allocation change substantially with ecological succession triggered by glacier retreat. Traits associated to nitrogen cycling show little change. We also found that flowering start shifted earlier in the season while flowering period increased with glacier retreat.Conclusion: Our results demonstrate the pervasive impact of glacier extinction on the functioning of plant communities. Changes in functional mean and functional variation indicate shifts in niche position and niche breadth which could have implications for species adaptation to changing environments.