Plant Pollinator Networks along a Gradient of Urbanisation

• Published in: PloS one Vol. 8; no. 5; p. e63421
• Main Authors: Geslin, Benoît, Gauzens, Benoit, Thébault, Elisa, Dajoz, Isabelle
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22.05.2013; Public Library of Science (PLoS)
• Subjects: Agricultural land; Animal reproduction; Animals; Apis mellifera; Bees; Bees - physiology; Biology; Biota - physiology; Breeding success; Bumblebees; Community structure; Conservation; Ecology; Ecology, environment; Ecosystem; Ecosystems; Evolution; Flowers; Flowers & plants; Flowers - physiology; Functional groups; Habitat loss; Habitats; Insects; Intensive farming; Landscape; Life Sciences; Morphology; Networks; Organic farming; Plant communities; Plant populations; Plant reproduction; Plant species; Plants; Pollen - physiology; Pollination - physiology; Pollinators; Reproduction; Studies; Suburban areas; Success; Symbiosis; Syrphidae; Trends; Urban agriculture; Urban areas; Urbanization; France
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0063421

Habitat loss is one of the principal causes of the current pollinator decline. With agricultural intensification, increasing urbanisation is among the main drivers of habitat loss. Consequently studies focusing on pollinator community structure along urbanisation gradients have increased in recent years. However, few studies have investigated how urbanisation affects plant-pollinator interaction networks. Here we assessed modifications of plant-pollinator interactions along an urbanisation gradient based on the study of their morphological relationships. Along an urbanisation gradient comprising four types of landscape contexts (semi-natural, agricultural, suburban, urban), we set up experimental plant communities containing two plant functional groups differing in their morphological traits ("open flowers" and "tubular flowers"). Insect visitations on these communities were recorded to build plant-pollinator networks. A total of 17 857 interactions were recorded between experimental plant communities and flower-visitors. The number of interactions performed by flower-visitors was significantly lower in urban landscape context than in semi-natural and agricultural ones. In particular, insects such as Syrphidae and solitary bees that mostly visited the open flower functional group were significantly impacted by urbanisation, which was not the case for bumblebees. Urbanisation also impacted the generalism of flower-visitors and we detected higher interaction evenness in urban landscape context than in agricultural and suburban ones. Finally, in urban context, these modifications lowered the potential reproductive success of the open flowers functional group. Our findings show that open flower plant species and their specific flower-visitors are especially sensitive to increasing urbanisation. These results provide new clues to improve conservation measures within urbanised areas in favour of specialist flower-visitors. To complete this functional approach, studies using networks resolved to the species level along urbanised gradients would be required.