Biology subjects

Klein, A.-M.

Publications and source records attributed to Klein, A.-M..

12 recordsLinked to original sources

bioRxiv2026

Ground-nesting bee survival after soil translocation and disturbance

Ground-nesting wild bees require suitable soil conditions for their below-ground development and overwintering life stages. Understanding how soil translocation and disturbance affect individuals and the following generations of bees is important for identifying conservation measures for ground-nesting wild bees. We investigated the effects of soil translocation and disturbance on the ground-nesting solitary spring mining bee Colletes cunicularius. In a replicated controlled design, we compared the effects of soil translocation with different degrees of disturbance on the number of surviving bees and the emergence time. We found that soil translocation and disturbance reduced bee survival but did not result in complete mortality, with some individuals surviving even under severe soil disturbance. There was no evidence that soil disturbance affected the timing of spring emergence, suggesting that disturbance is unlikely to alter the timing of nest construction and, consequently, the production of the next generation. Our results indicate that translocating soil containing overwintering bees could be a promising conservation measure to compensate for habitat loss caused by land conversion.

zoology↗

bioRxiv2026

Functional niche attributes shape species interaction roles in ecological networks

Identifying how species interact in ecological networks is key to understanding species' contributions to ecosystem functioning, but can be difficult to establish in species-rich communities. Functional niches, which capture broader ecological strategies, are often easier to assess and could help approximate species' interaction roles. We tested this by integrating species interaction and leaf functional trait data of tree species and leaf-associated interaction types from a large-scale forest biodiversity experiment. We found that identity, variability, and similarities of functional niches shaped corresponding aspects of interaction roles. Interestingly, however, this association inversed in the case of functional niche variability, which decreased instead of increased the variability of species interactions. This suggests a potential trade-off between processes that determine variability in functional and interaction space. Furthermore, effects were not constrained within aspects, with similarities of interactions being particularly responsive to most tested niche aspects, indicating that interaction-based competition among plants is particularly sensitive to functional niche differences. Moreover, many effects of functional niches depended on tree species biomass and tree species richness, highlighting the importance of the larger ecological context for determining species interaction roles. Together, our findings show that species' interaction roles, while clearly altered by, are not simply a consequence of functional niches. Instead, interaction roles integrate multiple aspects of functional niches depending on species performances and community composition and can therefore be crucial for anticipating ecosystem change.

ecology↗

bioRxiv2026

Annual ploughing turns wildflower plantings into ecological traps for ground-nesting wild bees

Wildflower plantings are an important conservation measure for supporting wild bee diversity. They aim to enhance floral resources for nutrition, but do not explicitly consider that bees also require suitable nesting and overwintering resources. Wildflower plantings may provide nesting habitat for ground-nesting bees, but the effects of soil management, e.g. ploughing, on ground-nesting bees are hardly known. To study how ploughing and age of wildflower plantings affect ground-nesting bees, we sampled bees on ploughed and unploughed wildflower plantings aged 0-4 years. We used emergence traps to sample bees directly after emergence from the ground, allowing inference on nest numbers. We found that ploughing and wildflower planting age negatively affected overwintering bee nest numbers. Nesting peaked in the year of wildflower planting establishment and declined thereafter, indicating lower habitat suitability at later successional stages. Annual ploughing caused the greatest reduction in nest numbers (-72 %), providing evidence for an ecological trap.

ecology↗

bioRxiv2026

Multitrophic interaction networks mediate biodiversity effects on ecosystem multifunctionality

Biodiversity loss threatens the multifunctionality of ecosystems on which human well-being ultimately depends. Changes in multitrophic species interactions may be key to explaining the ecological consequences of biodiversity loss, but research explicitly linking species interactions and ecosystem multifunctionality remains rare. To assess interaction-mediated biodiversity effects and underlying mechanisms, characterizing the structure of species interaction networks is invaluable. Using comprehensive species interaction and ecosystem functioning data from a large-scale tree biodiversity experiment, we find consistent effects of the structure of species interaction networks on ecosystem multifunctionality across multiple types of antagonistic and mutualistic interactions. While positive effects of network size align with expected positive effects of multitrophic species diversity, positive effects of niche overlap among interacting species and negative effects of highly connected species (i.e. high linkage density) reveal additional, interaction-mediated drivers of multifunctionality. Specifically, the effects of niche overlap suggest benefits of functionally similar species, and the effects of linkage density underscore the importance of specialized interactions in promoting ecosystem multifunctionality. These findings emphasize that to effectively safeguard ecosystem service provisioning, ecosystem management and biodiversity conservation not only need to account for biodiversity changes at multiple trophic levels, but also explicitly for how species interact among each other.

ecology↗

bioRxiv2026

Cavity-nesting bees combine forest nesting habitats with surrounding floral resources in a subtropical forest diversity experiment

Wild bees face declines, and forests may serve as critical habitats for pollinators. However, how forest composition and the associated floral environment shape pollen provisioning and resource partitioning among cavity-nesting bees remains poorly understood. Here, we leveraged BEF-China, a large-scale subtropical forest biodiversity experiment with experimentally controlled plant (tree and shrub) communities, to investigate how forest composition and spatial context shape pollen provisioning, resource partitioning, and reproductive success of cavity-nesting bees. We used DNA metabarcoding to analyze floral composition of pollen provisioned by five cavity-nesting bee species, with samples collected from BEF-China across three years (2022- 2024). By comparing pollen taxonomic composition from whole-nest pooled samples and individual brood-cell samples with the experimentally planted species pool, we characterized dietary patterns and temporal dynamics of five bee species. Bees primarily relied on floral resources from the surrounding landscape, with planted trees providing essential but temporally restricted pollen supplements during specific phenological stages. Co-occurring bee species exhibited staggered nesting phenology and distinct dietary preferences for different plant families, with fine-scale resource differentiation even during periods of phenological overlap. Our results suggest that managed forests support cavity-nesting bees by providing critical woody floral resources during specific phenological gaps and offering stable nesting environments. To mitigate pollinator declines, forest management should prioritize maintaining diverse, phenologically complementary flowering vegetation within and surrounding forest stands. This ensures temporal continuity of pollen availability throughout the nesting season, which is particularly crucial for restoring pollinator services in simplified forest landscapes.

ecology↗

bioRxiv2026

Moisture reduces saproxylic bee, wasp, and parasitoid diversity in lying and standing deadwood

Saproxylic insect community assembly is structured by deadwood and forest habitat gradients, as well as biotic interactions such as competition, predation, and parasitism. However, co-variation between abiotic and biotic conditions limits our ability to disentangle their contributions. Furthermore, a focus on beetles in temperate and boreal forests has left important taxonomic and geographic knowledge gaps. Here, we tested how experimentally manipulated tree diversity, deadwood position (lying vs. standing), and biotic interactions with a dominant antagonist (ant exclusion) structure communities of deadwood-cavity-nesting bees, wasps, and their parasitoids in a subtropical forest. Lying deadwood supported less diverse and abundant communities than standing deadwood while retaining approximately twice as much moisture. Moreover, host emergence declined along moisture gradients within each deadwood type. Together, these patterns identify substrate moisture as an important factor limiting bee and wasp communities nesting in deadwood - reflecting reduced brood production, survival, or both - and as a candidate driver for their positive association with standing deadwood in forests. By contrast, neither ant exclusion nor observed ant occurrence was associated with host or parasitoid responses. Because standing deadwood is typically scarce in managed forests, our findings support retaining or creating standing deadwood structures alongside lying deadwood and, more broadly, promoting dry and elevated nesting substrates for cavity-nesting bees and wasps in conservation and restoration measures.

ecology↗

bioRxiv2025

Reducing ploughing promotes ground-nesting flying insects

Many flying insects, such as bees, wasps, and hoverflies, live aboveground, but depend on soil for nesting, development, and overwintering. In agricultural landscapes, soil is managed for production and therefore frequently subjected to disturbances such as ploughing. The impacts of ploughing on flying insects that spend part of their life cycle belowground remain largely unknown. To investigate the effects of ploughing on ground-nesting flying insects, we conducted a two-year field experiment in flower strips subjected to different treatments, ranging from annual ploughing to four years without ploughing. Insects emerging from the soil were sampled using emergence traps, allowing a direct assessment of their response to ploughing at different frequencies. For each treatment, we measured insect biomass, abundance, and body size. We found that ploughing substantially reduced flying insect biomass. When sites were left unploughed, biomass increased rapidly, particularly during the first years of recovery. However, regardless of the time since the last disturbance, ploughing always reduced insect biomass to similarly low levels, driven primarily by declines in the abundance of large insects. Our findings highlight that even moderate reductions in ploughing frequency, for example, only every second year, can benefit ground-nesting flying insects and point to the potential for incorporating reduced ploughing frequencies into agricultural management and agri-environmental schemes.

ecology↗

bioRxiv2024

Multi-dimensionality of tree communities structure host-parasitoid networks and their phylogenetic composition

Environmental factors can influence ecological networks, but these effects are poorly understood in the realm of the phylogeny of host-parasitoid interactions. Especially, we lack a comprehensive understanding of the ways that biotic factors, including plant species richness, overall community phylogenetic and functional composition of consumers, and abiotic factors such as microclimate, determining host-parasitoid network structure and host-parasitoid community dynamics. To address this, we leveraged a five-year dataset of trap-nesting bees and wasps and their parasitoids collected in a highly-controlled, large-scale subtropical tree biodiversity experiment. We tested for effects of tree species richness, tree phylogenetic and functional diversity, and species and phylogenetic composition on species and phylogenetic diversity of both host and parasitoid communities and the composition of their interaction networks. We show that multiple components of tree diversity and canopy cover impacted both, species and phylogenetic composition of hosts and parasitoids. Generally, phylogenetic associations between hosts and parasitoids reflected non-randomly structured interactions between phylogenetic trees of hosts and parasitoids. Further, host-parasitoid network structure was influenced by tree species richness, tree phylogenetic diversity, and canopy cover. Our study indicates that the composition of higher trophic levels and corresponding interaction networks are determined by plant diversity and canopy cover especially via trophic links in species-rich ecosystems.

ecology↗

bioRxiv2023

Plant-pollinator interactions in apple orchards from a production and conservation perspective

In an agricultural landscape, production and conservation ideally go hand in hand. In a win-win scenario, conservation measures provide support for biodiversity and crop production, mediated by pollination for example. Hedges and flower strips are conservation measures that support pollinating insects, such as wild bees and hoverflies. They can be beneficial for crop pollination, but also harmful by dragging away pollinators from crops if flowering simultaneously. Here, we studied plant-pollinator interactions from two different perspectives. First we look at the apple-flower/production perspective investigating whether plant-pollinator networks in apple orchards differ with adjacent flower strips and hedges compared to isolated orchards. With help of the Bayes factor, we investigated similarity and conclude that there are no differences between pollination networks with or without adjacent flower strips and hedges. Second, we look at the pollinator/conservation perspective and analyse the impact of hedges and flower strips on pollinators and their interactions with plants before and after the apple bloom in April. We show that apple pollinators use more flower resources in flower strips and hedges across the whole season compared to isolated orchards. In orchards with flower strips and hedges interactions are more constant over time. We conclude that flower strips and hedges are beneficial for conservation of apple pollinators without being harmful for apple flower pollination being crucial for production.

ecology↗

bioRxiv2022

Tree species and genetic diversity increase productivity via functional diversity and trophic feedbacks

Addressing global biodiversity loss requires an expanded focus on multiple dimensions of biodiversity. While most studies have focused on the consequences of plant interspecific diversity, our mechanistic understanding of how the diversity within a given plant species (genetic diversity) affects plant productivity remains limited. Here, we use a tree species x genetic diversity experiment to disentangle the effects of species diversity and genetic diversity, and how they are related to tree functional diversity and trophic feedbacks. Tree species as well as genetic diversity increased tree productivity via increased tree functional diversity, reduced soil fungal diversity and marginally reduced herbivory. The effect of tree genetic diversity on productivity was partly different between tree species monocultures and mixtures: the functional diversity effect resulting from tree genetic diversity was only found in tree species monocultures, but the trophic feedbacks via herbivory were similar in species monocultures and mixtures. Given the complexity of interactions between tree species and genetic diversity, tree functional diversity and trophic feedbacks on productivity, we suggest that both tree species and genetic diversity should be considered in reforestation.

ecology↗

bioRxiv2021

Long-term monitoring reveals topographical features and vegetation explain winter habitat use of an Arctic rodent

Collapsing lemming cycles have been observed across the Arctic, presumably due to global warming creating less favorable winter conditions. The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of arctic lemmings. However, few studies so far investigated habitat use during the arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat features for their winter refugi. We examined yearly numbers and distribution of 22,769 winter nests of the collared lemming Dicrostonyx groenlandicus from an ongoing long-term research on Traill Island, Northeast Greenland, collected between 1989 and 2019, and correlated this information with data on dominant vegetation types, elevation and slope. We specifically asked if lemming nests were more frequent at sites with preferred food plants such as Dryas octopetala x integrifolia and at sites with increased snow cover. We found that the number of lemming nests was highest in areas with a high proportion of Dryas heath, but also correlated with other vegetation types which suggest some flexibility in resource use of wintering lemmings. Conversely, they showed a distinct preference for sloped terrain, probably as it enhances the formation of deep snow drifts which increases the insulative characteristics of the snowpack and protection from predators. With global warming, prime lemming winter habitats may become scarce through alteration of snow physical properties, potentially resulting in negative consequence for the whole community of terrestrial vertebrates.

ecology↗

bioRxiv2017

Strong positive biodiversity-productivity relationships in a subtropical forest experiment

Forest ecosystems contribute substantially to global terrestrial primary productivity and climate regulation, but, in contrast to grasslands, experimental evidence for a positive biodiversity-productivity relationship in highly diverse forests is still lacking1. Here, we provide such evidence from a large forest biodiversity experiment with a novel design2 in subtropical China. Productivity (stand-level tree basal area, aboveground volume and carbon and their annual increment) increased linearly with the logarithm of tree species richness. Additive partitioning3 showed that increasing positive complementarity effects combined with weakening negative selection effects caused a strengthening of the relationship over time. In 2-species mixed stands, complementary effects increased with functional distance and selection effects with vertical crown dissimilarity between species. Understorey shrubs reduced stand-level tree productivity, but this effect of competition was attenuated by shrub species richness, indicating that a diverse understorey may facilitate overall ecosystem functioning. Identical biodiversity-productivity relationships were found in plots of different size, suggesting that extrapolation to larger scales is possible. Our results highlight the potential of multi-species afforestation strategies to simultaneously contribute to mitigation of climate change and biodiversity restoration.

ecology↗