In this paper, we summarize the published literature in the growing field of wild bee functional ecology and review which functional trait-based analyses have been carried out on wild bees in cities thus far, summarize which wild bee species traits have been considered and evaluate any consistent wild bee trait–environment relationships across studies.
„Wild bees in urban grasslands: Urbanisation, functional diversity and species traits“ has been published in Landscape and Urban Planning. We found that urbanisation was not related to neither taxonomic nor functional diversity in bee communities of urban grasslands. However, endangered bee species responded negatively to the isolation of grasslands but positively to flower coverage. Urbanisation, previous restoration efforts and site type filtered the functional composition of bee communities in terms of species traits related to diet and nesting. Our results substantiate the role of urban habitats for functionally diverse bee communities, including rare and endangered species, and indicate pathways towards enhancing habitat functions of urban grasslands for wild bees by improving the connectivity of urban grassland patches within the urban matrix, and more locally by adjusting management to maintain flower coverage in grasslands.
One of the main objectives of our project is to analyse interactions between honey bees and wild bees (and other wild pollinators) in urban habitats. Of particular interest is the question of whether there is food competition between honey and wild bees and which role environmental conditions – such as amount of flowering plants – play. We are currently conducting experiments to answer this question.
Implementing the Berlin Bee Strategy for conservation of bees and other pollinators in Berlin by optimising the protection of wild bees (funded bei Senatsverwaltung für Umwelt, Verkehr und Klimaschutz Berlin) – more info coming soon.
„Urbanisation modulates plant-pollinator interactions in invasive vs. native plant species“ has been published in Scientific Reports. The article is open access.
In this article, we show that invasive black locust (Robinia pseudoacacia) is a “pollinator-friendly” tree and attracts not only honey bees but also wild bees and other wild pollinators. However, we also found that attractiveness of black locust decreases with increasing urbanisation.
Recently, Märkische Entomologische Nachrichten has published two faunistic papers. The first one in on Carabid beetles (Coleoptera: Carabidae) of dry grasslands in Berlin (and Brandenburg). At 52 dry grassland sites in Berlin and Brandenburg we sampled 106 species including a new record for Berlin and numerous endangered species. The second one, Wild bees of dry grasslands in Berlin, summarises bee data from 49 dry grasslands in Berlin. Both papers highlight the importance of urban sites as secondary habitats for rare and endangered invertebrates.
The German Society of general and applied Entomology (DGaaE) and the German Scientific Society for Plant Protection and Plant Health (DPG) organised a conference on insect diversity in cities (III. Urbane Pflanzen Conferenz). I contributed a talk on habitat function of urban meadows for wild bees with emphasis on urbanisation effects (see Abstract in German). Due to a very diverse audience with many relevant stakeholders and decision-makers (e.g. scientists, gardeners, landscape planners, landscape architects, authorities and NGOs) it was possible to elaborate this topic from different perspectives. At the end we had very interesting – sometimes controverse – discussions to develop recommendations how to make cities more insect friendly and to comment on the new white book „Grün in der Stadt“ which was recently send out for preview. The official presentation of the white book will be in May 2017.
Disentangling urban habitat and matrix effects on wild bee specieshas been published in PeerJ.
Authors Fischer LK, Eichfeld J, Kowarik I & Buchholz S
Abstract In face of a dramatic decline of wild bee species in many rural landscapes, potential conservation functions of urban areas gain importance. Yet effects of urbanization on pollinators, and in particular on wild bees, remain ambiguous and not comprehensively understood. This is especially true for amenity grassland and extensively managed wastelands within large-scale residential housing areas. Using Berlin as study region, we aimed to investigate (a) if these greenspaces are accepted by wild bee assemblages as foraging habitats; (b) how assemblage structure of bees and individual bee species are affected by different habitat (e.g., management, flower density) and urban matrix variables (e.g., isolation, urbanization); and (c) to what extend grassland restoration can promote bees in urban environments. In summer 2012, we collected 62 bee species belonging to more than 20 % of the taxa known for Berlin. Urbanization significantly affected species composition of bees; 18 species were affiliated to different levels of urbanization. Most bee species were not affected by any of the environmental variables tested, and urbanization had a negative effect only for one bee species. Further, we determined that restoration of diverse grasslands positively affected bee species richnesss in urban environments. We conclude that differently structured and managed greenspaces in large-scale housing areas can provide additional foraging habitats and refuges for pollinators. This supports approaches towards a biodiversity friendly management within urban regions and may be of particular importance given that anthropogenic pressure is increasing in many rural landscapes.