Taxonomic and functional trait diversity of wild bees in different urban settings

Abstract

Urbanization is one of the major anthropogenic processes contributing to local habitat loss and extirpation of numerous species, including wild bees, the most widespread pollinators. Little is known about the mechanisms through which urbanization impacts wild bee communities, or the types of urban green spaces that best promote their conservation in cities. The main objective of this study was to describe and compare wild bee community diversity, structure, and dynamics in two Canadian cities, Montreal and Quebec City. A second objective was to compare functional trait diversity among three habitat types (cemeteries, community gardens and urban parks) within each city. Bees were collected using pan traps and netting on the same 46 sites, multiple times, over the active season in 2012 and 2013. A total of 32,237 specimens were identified, representing 200 species and 6 families, including two new continental records, Hylaeus communis Nylander (1852) and Anthidium florentinum (Fabricius, 1775). Despite high community evenness, we found significant abundance of diverse species, including exotic ones. Spatio-temporal analysis showed higher stability in the most urbanized city (Montreal) but low nestedness of species assemblages among the three urban habitats in both cities. Our study demonstrates that cities are home to diverse communities of wild bees, but in turn affect bee community structure and dynamics. We also found that community gardens harbour high levels of functional trait diversity. Urban agriculture therefore contributes substantially to the provision of functionally diverse bee communities and possibly to urban pollination services.

City parks vs. natural areas - is it possible to preserve a natural level of bee richness and abundance in a city park?

“…Many researchers report that natural habitats display greater diversity of pollinators compared to urban areas (McIntyre and Hostetler 2001;Eremeeva and Sushchev 2005;Matteson et al 2008;Ahrné et al 2009). At the same time, data provided by other authors show that cities are important habitats for a considerable number of bee species (Saure 1996;Frankie et al 2005;Banaszak-Cibicka and Żmihorski 2012;Frankie et al 2013;Baldock et al 2015;Cariveau and Winfree 2015;Sirohi et al 2015;Threlfall et al 2015;Hall et al 2017;Normandin et al 2017), and urbanization has a lesser effect on bees than on other insects (Deguines et al 2012). For instance, urban parks in San Francisco, USA, support higher mean abundances of bumblebees (Bombus spp.)…”

Patch and landscape‐scale variables influence the taxonomic and functional composition of beetles in urban greenspaces

“…, Normandin et al. ). With greater study, documenting the distribution of functional traits within a particular arthropod community can be used to predict the conservation value of focal habitats as well as potential desired insect‐mediated ecosystem services such as biological control, pollination, and nutrient cycling (Mulder and Vonk , Vonk et al.…”

Are all urban green spaces a favourable habitat for pollinator communities? Bees, butterflies and hoverflies in different urban green areas

“…frequent mowing, cutting down trees, replacing waste land, use of impervious materials) often changes green infrastructure and could, as a result, impoverish these habitats for urban flora and fauna (Pauleit & Breuste, 2011). Furthermore, it has to be taken into consideration that cities are a part of the larger landscape, and that urban areas are becoming increasingly important ecosystems, promoting the biodiversity of their surroundings (Goddard et al, 2010;Kowarik, 2011;Normandin et al, 2017;Werner & Kelcey, 2017). However, a recent study demonstrated that urban residents attached importance not only to the aesthetic character but also to the conservational aspects of urban green space (Southon et al, 2017).…”