Abstract
Urbanization is one of the primary forces driving worldwide pollinator decline. Moderate urban expansion with appropriate green space planning can help in maintaining pollinator diversity and pollination service. We investigated the relative effects of landscape and local factors on the diversity of flower-visitor functional groups in a moderately urbanized city, Wuhan, located in central China. We found that the proportion of impervious surface had no significant effect on the number of visitations, but it was negatively associated with the diversity of flower-visitor groups. The number of visitations by Halictidae and Lepidoptera correlated positively with local flower density and flowering plant species richness, respectively. Flowering plant species richness was also positively correlated with the diversity of flower-visitor groups. The proportion of green space was negatively associated with the visitation number of Muscidae and the overall diversity of flower-visitor groups, revealing the potential influence of green space quality on pollinator assemblage. The pollination networks under three urbanization levels (with a total of 11 flower visitor groups and 43 plant species) were asymmetric, highly nested, and generalized. The suburb sites contained the highest diversity of interactions. Core flowering plants (Oenothera speciosa, Coreopsis grandiflora and Cyanus segetum) are exotic species with attractive flowers. Improving green space quality (high flower density and flowering plant species richness) and using attractive native flowering plants (Nandina domestica, Rosa chinensis, Astragalus sinicus, Cirsium arvense var. integrifolium, and Zabelia biflora) would enhance the function of urban green space to maintain pollinator diversity and ecosystem stability.
Highlights
The sustainable development of human societies relies on ecosystem services provided by nature, among which pollination service is vital and vulnerable [1]
Some studies have found that moderate urban expansion or artificial land-use may increase the number of certain pollinators and their pollination services
We investigated the effects of landscape factors and local factors driven by urbanization on the diversity of flower visitors in urban and suburban green spaces in
Summary
The sustainable development of human societies relies on ecosystem services provided by nature, among which pollination service is vital and vulnerable [1]. Pollinators, such as bees, butterflies, and hoverflies have declined globally [2–6]. Urbanization is a dynamic process involving dramatic and continuous changes in land use, including a decrease in bare land, an increase in the area covered by impervious surfaces, and the loss of natural vegetation [10,12,13]. Urbanization causes habitat loss and reduces the habitat suitability of pollinators, and reduces the abundance and diversity of pollinators [14–17]. Urban green spaces can provide suitable alternative habitats and food sources for pollinators [19,20]. Suitable urbanized areas may play an important role in pollinator conservation
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