Marianne Strand Torvanger

• Sydenham, Markus A. K.; Nielsen, Anders; Dupont, Yoko L.; Rasmussen, Claus; Madsen, Henning B. & Torvanger, Marianne S. [Show all 7 contributors for this article] (2025). Role of forest edges and other seminatural linear landscape features in structuring wild bee habitat connectivity in intensively managed landscapes. Conservation Biology. ISSN 0888-8892. 39(6). doi: 10.1111/cobi.70152. Full text in Research Archive Show summary

  Pollinator conservation schemes typically focus on conserving existing, restoring degraded, or creating new wild bee habitats. Their effectiveness depends on dispersal corridors enabling habitat colonization by bees. However, the role of seminatural linear landscape structures (LLS) in connecting pollinator communities across intensively managed landscapes remains poorly understood. We analyzed 953 occurrences of wild bees comprising 79 nonparasitic species sampled at 68 study sites across a Norwegian and a Danish landscape. We first tested whether bee species richness was positively associated with the lengths of seminatural LLS in bee foraging ranges of study sites while controlling for local plant species richness. We then combined maps identifying seminatural LLS with least‐cost path (LCP) analysis to determine whether bee species compositional similarity, a proxy for connectivity, decreased as LCP length increased. The length of seminatural LLS, such as forest edges, was positively correlated with bee species richness and habitat connectivity. Specifically, wild bee species richness sampled along roadsides increased as the length of seminatural LLS increased in 1.5 km circles around the study sites, and increased as local plant species richness increased. The most likely dispersal routes between our bee communities tracked forest edges. The length of LCPs provided better models of bee species compositional similarity than geographic distance, suggesting that seminatural LLS, particularly forest edges, act as dispersal corridors in intensively managed landscapes. However, bee species compositional similarity among communities depended on site‐specific plant species richness and similarity in plant community composition, which highlights the importance of improving the habitat quality of seminatural LLS if they are to function as dispersal corridors. Our findings suggest that maps of LCPs can be used to identify important dispersal corridors between bee habitats and to direct wild bee habitat management actions along seminatural LLS to facilitate the dispersal of bees in intensively managed landscapes.

• Furness, Lydia Hildebrand; Sabin, Richard; Torvanger, Marianne Strand; Kersten, Oliver Sven; Barrett, James Harold & Star, Bastiaan (2025). Historical Collections of Tropical Marine Mammals Are an Excellent Resource for Ancient DNA. Molecular Ecology Resources. ISSN 1755-098X. 25(7), p. 1–16. doi: 10.1111/1755-0998.70015. Full text in Research Archive Show summary

  ABSTRACT The ability to predict ancient DNA sequencing success in natural history collections is critical to reducing the amount of destructive sampling of a finite resource. So far, studies investigating such success have predominantly focused on taxa with ranges restricted to temperate or cold environments at northern latitudes, which likely aids DNA preservation. Here, we report remarkably high aDNA sequencing success in Sirenia , herbivorous marine mammals of which the distribution is currently constrained to the global tropics. We investigate 91 samples from 85 specimens comprising all four contemporary species and one extinct species, comparing different sample types (cranial/post‐cranial bone, skin and cartilage), species, collections, and material age. We obtained remarkably high (e.g., > 20%) endogenous DNA preservation for the majority (e.g., ~57% percent) of samples. Sequencing success was linked to sample type, with cranial bones (including petrous and tympanic bones) yielding significantly higher endogenous DNA. Additionally, we obtained variable, but potentially superior DNA results for preserved cartilage and hide samples that can be associated with historical bone. Although such tissue is not always present, this type of material is easy to sample, with very limited destructive impacts on the associated bones, and we therefore highlight its untapped potential as a source of DNA. Overall, our results show the high success of ancient DNA retrieval from historical collections of species with a tropical distribution, expanding on the types of specimens that are available for temporal genomic analyses.

• Torvanger, Marianne Strand; Dupont, Yoko L.; Olesen, Jens M.; Rasmussen, Claus; Madsen, Henning Bang & Star, Bastiaan [Show all 7 contributors for this article] (2025). The Distribution of Wild Bee Species Along a Latitudinal Gradient in Northern Europe Depends on Their Flower Preferences. Diversity and Distributions: A Journal of Conservation Biogeography. ISSN 1366-9516. 31(2), p. 1–13. doi: 10.1111/ddi.70001. Full text in Research Archive Show summary

  Aim: The functional diversity of bees contribute to the maintenance of plant biodiversity because different species of wild beesprefer and pollinate different plants. Many bees, in particular species with narrow flower preferences or specialised habitatrequirements, are threatened by landscape homogenisation and climate change. Nonetheless, we still lack an understanding oflarge-scale impacts of anthropogenic stressors on the distribution of wild bee species with different flower preferences.Location: Northern Europe: Norway, Denmark and Germany.Methods: We combine a dataset comprising ~30,000 observations of presences or absences of bee occurrences from structuredsurveys at 269 sites in northern Europe to investigate if flower preferences modulate species distributions across multiple envi-ronmental gradients. Bees were assigned a continuous functional trait separating preference for short vs. tubular flowers.Results: We observe that bee flower preference for either tubular flowers (Fabaceae) or plants with shallow flowers (includingApiaceae and Brassicaceae) can be described by a continuous flower preference trait score. The likelihood of observing a beealong a latitudinal gradient—encompassing variation in temperature, atmospheric N deposition and elevation—is dependent onits flower preference trait score. Specifically, bees with preferences for tubular flowers have a higher likelihood of occurrencewith higher latitudes, while bees with preference for non-tubular flowers increase towards the south.Main Conclusions: Our results improve our understanding of how species-specific variation in flower preferences drivescommunity-wide shifts in diversity and can therefore help devise region-specific conservation strategies. bees | conservation | functional ecology | gradients | landscape | pollinators | spatial distributions | traits | wild bee

• Sydenham, Markus A. K.; Nielsen, Anders; Dupont, Yoko L.; Rasmussen, Claus; Madsen, Henning Bang & Torvanger, Marianne Strand [Show all 7 contributors for this article] (2024). Forest edges and other semi-natural habitat edges increase wild bee species richness and habitat connectivity in intensively managed temperate landscapes. BioRxiv. ISSN 0362-4331. doi: 10.1101/2024.07.05.602209. Full text in Research Archive Show summary

  Pollinator conservation schemes are typically focused on conserving existing-, restoring degraded- or establishing new wild bee habitats. The effectiveness of such conservation schemes depends on the presence of dispersal corridors that allow habitat colonization by bees. Nonetheless, we lack an understanding of the role of semi-natural habitats edges on the connectivity of pollinator communities across intensively managed landscapes. Here, we use data from wild bee communities comprising 953 occurrences from 79 species of non-parasitic bees, sampled at 68 locations distributed across a Norwegian and a Danish landscape to show that the proportion of semi-natural habitat edges is positively correlated to bee species richness and habitat connectivity. Specifically, we found that wild bee species richness sampled along roadsides increased with the proportion of semi-natural habitat edges within1.5 km of the study sites and with local plant species richness. We combined maps showing the proportion of seminatural habitat edges with least cost path analysis to find the most likely dispersal route between our bee communities. We find that these least cost path lengths provide better models of bee species compositional similarity than geographic distance (|ΔAICc| > 2), suggesting that seminatural habitat edges act as dispersal corridors in intensively managed landscapes. However, we also find that compositional similarity between communities depend on site-specific plant species richness stressing the importance of improving the habitat quality of edge habitats if they are to function as dispersal corridors. We discuss potential management options for improving wild bee habitat conditions along seminatural habitat edges and illustrate how maps of least cost paths can be used to identify dispersal corridors between pollinator habitats of conservation priority. Maps of dispersal corridors can be used to direct wild bee habitat management actions along seminatural habitat edges to facilitate the dispersal of bees between larger grassland habitats. Bees, Connectivity, Conservation planning, Pollinators, Restoration, Grassland

• Sydenham, Markus A. K.; Dupont, Yoko L.; Nielsen, Anders; Olesen, Jens M.; Madsen, Henning Bang & Skrindo, Astrid Brekke [Show all 19 contributors for this article] (2024). Climatic conditions and landscape diversity predict plant–bee interactions and pollen deposition in bee-pollinated plants. Ecography. ISSN 0906-7590. 2024(9), p. 1–14. doi: 10.1111/ecog.07138. Full text in Research Archive Show summary

  Climate change, landscape homogenization, and the decline of beneficial insects threaten pollination services to wild plants and crops. Understanding how pollination potential (i.e. the capacity of ecosystems to support pollination of plants) is affected by climate change and landscape homogenization is fundamental for our ability to predict how such anthropogenic stressors affect plant biodiversity. Models of pollinator potential are improved when based on pairwise plant–pollinator interactions and pollinator's plant preferences. However, whether the sum of predicted pairwise interactions with a plant within a habitat (a proxy for pollination potential) relates to pollen deposition on flowering plants has not yet been investigated. We sampled plant–bee interactions in 68 Scandinavian plant communities in landscapes of varying land-cover heterogeneity along a latitudinal temperature gradient of 4–8°C, and estimated pollen deposition as the number of pollen grains on flowers of the bee-pollinated plants Lotus corniculatus and Vicia cracca. We show that plant–bee interactions, and the pollination potential for these bee-pollinated plants increase with landscape diversity, annual mean temperature, and plant abundance, and decrease with distances to sand-dominated soils. Furthermore, the pollen deposition in flowers increased with the predicted pollination potential, which was driven by landscape diversity and plant abundance. Our study illustrates that the pollination potential, and thus pollen deposition, for wild plants can be mapped based on spatial models of plant–bee interactions that incorporate pollinator-specific plant preferences. Maps of pollination potential can be used to guide conservation and restoration planning.

• Sydenham, Markus A. K.; Venter, Zander; Eldegard, Katrine; Torvanger, Marianne Strand; Nowell, Megan Sara & Hansen, Silke [Show all 11 contributors for this article] (2023). The contributions of flower strips to wild bee conservation in agricultural landscapes can be predicted using pollinator habitat suitability models. Ecological Solutions and Evidence. 4(4). doi: 10.1002/2688-8319.12283. Full text in Research Archive Show summary

  1. Sowing flower strips along field edges is a widely adopted method for conserving pollinating insects in agricultural landscapes. To maximize the effect of flower strips given limited resources, we need spatially explicit tools that can prioritize their placement, and for identifying plant species to include in seed mixtures. 2. We sampled bees and plant species as well as their interactions in a semi- controlled field experiment with roadside/field edge pairs with/without a sown flower strip at 31 sites in Norway and used a regional spatial model of solitary bee species richness to test if the effect of flower strips on bee species richness was predictable from the modelled solitary bee species richness. 3. We found that sites with flower strips were more bee species rich compared to sites without flower strips and that this effect was greatest in areas that the re-gional solitary bee species richness model had identified to be particularly impor-tant for bees. Spatial models revealed that even within small landscapes there were pronounced differences between field edges in the predicted effect of sow-ing flower strips. 4. Of the plant species that attracted the most bee species, the majority mainly at-tracted bumblebees and only few species also attracted solitary bees. Considering both the taxonomic diversity of bees and the species richness of bees attracted by plants we suggest that seed mixes containing Hieracium spp. such as Hieracium umbellatum, Pilosella officinarum, Taraxacum spp., Trifolium repens, Lotus cornicula-tus, Stellaria graminea and Achillea millefolium would provide resources for diverse bee communities in our region. 5. Spatial prediction models of bee diversity can be used to identify locations where flower strips are likely to have the largest effect and can thereby provide manag-ers with an important tool for prioritizing how funding for agri- environmental schemes such as flower strips should be allocated. Such flower strips should con-tain plant species that are attractive to both solitary and bumblebees, and do not need to be particularly plant species rich as long as the selected plants comple-ment each other. agri-environmental schemes, bees, flower strips, networks, pollinators, restoration, spatial

View all works in NVA