A “plan bee” for cities: Pollinator diversity and plant-pollinator interactions in urban green spaces

Abstract

Green infrastructure in cities is considered to serve as a refuge for insect pollinators, especially in the light of an ongoing global decline of insects in agricultural landscapes. The design and maintenance of urban green spaces as key components of green infrastructure play a crucial role in case of nesting opportunities and for foraging insects. However, only few research has explored the impact of urban green space design on flower visitor communities, plant-pollinator interaction and the provision of the ecosystem service of pollination in cities. We investigated the abundance and diversity of pollinator communities in different urban park types in designed, standardized vegetation units, linked the visitation rates to the structural composition of the park types and derived indices for implemented pollination performances. The study was performed in two different structural park elements, flower beds and insect-pollinating trees. To gain a comprehensive understanding of the interaction between plants and pollinators, we calculated a plant-pollinator network of the recorded community in the investigation area. Visitation rates at different park types clearly showed, that the urban community gardens in comparison to other urban park types had a significantly higher abundance of pollinator groups, comparable to results found on a rural reference site. Tilia trees contributed significantly to the ecosystem service of pollination in investigated green spaces with a high supply of nectar and pollen during their flowering period. Calculations of pollination performances showed that recreational parks had comparably low visitation rates of pollinators and a high potential to improve conditions for the ecosystem service of pollination. The results indicated the strong potential of cities to provide a habitat for different groups of pollinators. In order to access this refuge, it is necessary to rely on near-natural concepts in design and maintenance, to create a wide range of flower diversity and to use even small green patches. Based on the findings, we encourage an integrated management of urban free spaces to consider parks as key habitats for pollinators in anthropogenic dominated, urban environments.

Supporting Bees in Cities: How Bees Are Influenced by Local and Landscape Features

“…Different park types can also vary in their ability to support pollinators. Recreational parks for example could improve floral quality [ 104 ] and planting gardens within these areas may be one means of accomplishing such a task [ 105 ]. Informal green spaces including those found interspersed throughout residential areas may be useful to pollinators if they exhibit variation in management intensity [ 106 ].…”

Association between land use, land cover, plant genera, and pollinator abundance in mixed-use landscapes

“…The lower importance of land use compared to land cover and plant genera is consistent with existing literature (e.g., De Palma et al 2016) and suggests that land use might become important only when extremely modified land-use types (e.g., pure agriculture, or urban) are considered (Millard et al 2021;Winfree et al 2009;Winfree et al 2011). The availability of natural habitat and floral resources present in and around different land-use types are more likely to affect pollinators; for example, (1) pollinators can make use of the pollen and nectar provided by plants in road verges or green infrastructure in agricultural and urban landscapes (Daniels et al 2020;Phillips et al 2019) and (2) agricultural landscapes with higher amount of high-quality habitat support a higher abundance and richness of pollinators than agricultural landscapes without such habitat (Kavanagh et al 2007;Kennedy et al 2013). The positive effect of plantation and pasture land-use types on pollinator taxa could be attributed to the low land-use intensity of the overall study area (Millard et al 2021) and/or, due to the availability of plantation and non-plantation forest cover and floral resources in plantations and pastures, respectively (Brito et al 2017;Kavanagh et al 2007;Kennedy et al 2013).…”

FORUM: Methodological shortcomings and lack of taxonomic effort beleaguer Australian bee studies

“… ‘solitary bees’ vs. ‘social bees’ (Daniels et al . 2020); honey bees, bumble bees, green metallic sweat bees (Halictidae), large other bees (>8 mm in length) and small other bees (4–8 mm in length; Mallinger et al . 2019); ‘pollinators’ (Pryke & Samways 2012); ‘small orange bee’, ‘white‐banded bee’ (Brown et al .…”