Effects of Landscape and Local Factors on the Diversity of Flower-Visitor Groups under an Urbanization Gradient, a Case Study in Wuhan, China

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.

The degree of urbanisation reduces wild bee and butterfly diversity and alters the patterns of flower-visitation in urban dry grasslands

“…This may indicate a very strong local filtering effect in the structure of butterfly communities 92 , 93 . Similarly, to hoverflies, butterflies benefited from high vegetation 36 , 94 . Butterfly species require plant structures for larval development and therefore rely on habitats with a sufficient amount of plant biomass and vegetation structure 36 , 59 .…”

Butterfly Diversity in a Rapidly Developing Urban Area: A Case Study on a University Campus

“…Several studies of insect diversity in urban areas (city parks, campuses, etc.) of China have shown that the improvement of the quality of green spaces (higher plant species richness and flower density) and the use of attractive native flowering plants can help reduce the negative effects of city expansion on pollinator diversity [14,82,88,[110][111][112]. Therefore, treating urban scenic spots and roads as 'hotspots' for insect conservation and properly managing green spaces within them could be an effective way to benefit the survival of urban butterfly species [113,114].…”

Agricultural landscape composition alters ant communities in maize fields more than plant diversity enrichment

“…Plant diversity enrichment management is particularly beneficial for natural enemies or other beneficial insects by providing energyrich nectar, a widely utilized food source for various insect orders, including Diptera, Coleoptera, and Hymenoptera (Nilsson et al 2016). Additionally, plant diversity enrichment contributes to local-level diversity (He et al 2022;Schmack and Egerer 2023). Increasing landscape complexity, achieved through composition, configuration, or heterogeneity changes, significantly and positively impacts biodiversity.…”