Land-use intensification and resulting habitat loss are put forward as the main causes of flower visitor decline. However, the impact of urbanization, the prime driver of land-use intensification in Europe, is poorly studied. In particular, our understanding of whether and how it affects the composition and functioning of flower visitor assemblages is scant, yet required to cope with increasing urbanization worldwide. Here, we use a nation-wide dataset of plant-flower visitor (Coleoptera, Diptera, Hymenoptera, Lepidoptera) interactions sampled by citizen scientists following a standardized protocol to assess macroecological changes in richness and composition of flower visitor communities with urbanization. We measured the community composition by quantifying the relative occurrence of generalist and specialist flower visitors based on their specialisation on flowering plant families. We show that urbanization is associated with reduced flower visitor richness and a shift in community composition toward generalist insects, indicating a modification of the functional composition of communities. These results suggest that urbanization affects not only the richness of flower visitor assemblages but may also cause their large-scale functional homogenization. Future research should focus on designing measures to reconcile urban development with flower visitor conservation.
Flower visitor communities data
This table provide the data of the 1606 flower visitors communities analysed as described in the main text of the manuscript.
Field “collection_id” is a unique ID number for each flower visitor community; field “long” and “lat” provide longitude and latitude of the site sampled. Field “volunteer_id” gives a unique ID number for each volunteer observing data. Field “prop_ins_withCSI” gives, for each flower visitor community, the proportion of insect that were available for the calculation of the CSI (i.e. for each collection, the proportion of insects with a defined specialisation index). Field “prop_urban_1km” is the proportion of urban areas within 1km of the sampling sites. Fields “richness_flovis” and “CSI_flovis” are respectively the richness and the Community Specialisation Index of the flower visitor communities.
Deguines et al 2016_flovisdata.xlsx
Deguines et al 2016_Coldata
This table provide the data of the 677 Coleoptera communities analysed as described in Appendix 1.
Field “collection_id” is a unique ID number for each Coleoptera community; field “long” and “lat” provide longitude and latitude of the site sampled. Field “volunteer_id” gives a unique ID number for each volunteer observing data. Field “prop_Col_withCSI” gives, for each Coleoptera community, the proportion of insect that were available for the calculation of the CSI (i.e. for each collection, the proportion of insects with a defined specialisation index). Field “prop_urban_1km” is the proportion of urban areas within 1km of the sampling sites. Fields “richness_Col” and “CSI_Col” are respectively the richness and the Community Specialisation Index of the Coleoptera communities.
Deguines et al 2016_Dipdata
This table provide the data of the 843 Diptera communities analysed as described in Appendix 1.
Field “collection_id” is a unique ID number for each Diptera community; field “long” and “lat” provide longitude and latitude of the site sampled. Field “volunteer_id” gives a unique ID number for each volunteer observing data. Field “prop_Dip_withCSI” gives, for each Diptera community, the proportion of insect that were available for the calculation of the CSI (i.e. for each collection, the proportion of insects with a defined specialisation index). Field “prop_urban_1km” is the proportion of urban areas within 1km of the sampling sites. Fields “richness_Dip” and “CSI_Dip” are respectively the richness and the Community Specialisation Index of the Diptera communities.
Deguines et al 2016_Hymdata
This table provide the data of the 1159 Hymenoptera communities analysed as described in Appendix 1.
Field “collection_id” is a unique ID number for each Hymenoptera community; field “long” and “lat” provide longitude and latitude of the site sampled. Field “volunteer_id” gives a unique ID number for each volunteer observing data. Field “prop_Hym_withCSI” gives, for each Hymenoptera community, the proportion of insect that were available for the calculation of the CSI (i.e. for each collection, the proportion of insects with a defined specialisation index). Field “prop_urban_1km” is the proportion of urban areas within 1km of the sampling sites. Fields “richness_Hym” and “CSI_Hym” are respectively the richness and the Community Specialisation Index of the Hymenoptera communities.
Deguines et al 2016_Lepdata
This table provide the data of the 337 Lepidoptera communities analysed as described in Appendix 1.
Field “collection_id” is a unique ID number for each Lepidoptera community; field “long” and “lat” provide longitude and latitude of the site sampled. Field “volunteer_id” gives a unique ID number for each volunteer observing data. Field “prop_Lep_withCSI” gives, for each Lepidoptera community, the proportion of insect that were available for the calculation of the CSI (i.e. for each collection, the proportion of insects with a defined specialisation index). Field “prop_urban_1km” is the proportion of urban areas within 1km of the sampling sites. Fields “richness_Lep” and “CSI_Lep” are respectively the richness and the Community Specialisation Index of the Lepidoptera communities.
