Plant-pollinator interactions in urban ecosystems worldwide: A comprehensive review including research funding and policy actions

Abstract

Urbanization has rapidly increased in recent decades and the negative effects on biodiversity have been widely reported. Urban green areas can contribute to improving human well-being, maintaining biodiversity, and ecosystem services (e.g. pollination). Here we examine the evolution of studies on plant-pollinator interactions in urban ecosystems worldwide, reviewing also research funding and policy actions. We documented a significant increase in the scientific production on the theme in recent years, especially in the temperate region; tropical urban ecosystems are still neglected. Plant-pollinator interactions are threatened by urbanization in complex ways, depending on the studied group (plant or pollinator [generalist or specialist]) and landscape characteristics. Several research opportunities emerge from our review. Research funding and policy actions to pollination/pollinator in urban ecosystems are still scarce and concentrated in developed countries/temperate regions. To make urban green spaces contribute to the maintenance of biodiversity and the provision of ecosystem services, transdisciplinary approaches (ecological-social-economic-cultural) are needed.

Keywords: Ecosystem service; Pollination; Scientometrics; Urban ecology; Urban green areas; Urbanization.

Fig. 1

Flow diagram representing the body of literature reviewed, research funding/grants and policy documents on plant–pollinator interactions in urban ecosystems, which were considered in this study (including counts of sources and exclusion criteria used to filter the body of literature, research funding/grants and policy documents into the final dataset reviewed). Search argument for the scientometric analysis in the Web of Science: “urban* and pollinat*”; search arguments for Dimensions Platform: urban, pollinator(s) and pollination. This diagram is based on The PRISMA Statement: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (sensu Moher et al. ; www.prisma-statement.org.)

Fig. 2

Growth of research effort through time on plant–pollinator interactions in urban ecosystems. Search was carried out in the Web of Science with the argument “urban* and pollinat*”, returning 634 articles, 157 of which were related to this topic and included in our database. *Number of articles for 2020 refers only to January and February

Fig. 3

Distribution of articles related to plant–pollinator interactions in urban ecosystems in countries with developed (light grey) (80.89%; N = 127) and developing economies (19.11%, N = 30) (dark grey). For the inclusion and exclusion criteria when searching articles at Web of Science (2020) (www.webofknowledge.com), please see the Flow diagram in Fig. 1. Bubble color represents the number of published articles; Bubble size represents the number of inhabitants (population) in each country, which are informed in the box at right (Data source: The United Nations 2019)

Fig. 4

Number of articles on plant–pollinator interactions in urban ecosystems a per the climatic zones: tropical, subtropical, temperate, Mediterranean, of the country of the study; b categories of nature of the study method; and c type of urban green space where the studies were developed: park, garden (public and/or private), road and/or public walkways and/or flowerbed, green roofs, university campus, cemetery, more than one category, urbanization gradient and others. Our search in the Web of Science with the argument “urban* and pollinat*” returned 634 articles, 157 of which were related to this topic and included in our database

Fig. 5

Number of articles on plant–pollinator interactions in urban ecosystems regarding the a origin of the plant(s) involved in the interaction with the study site; b pollination vector; and c categories of urbanization effect: neutral, positive, more than one effect, negative and not applicable in studies on this topic Our search in the Web of Science with the argument “urban* and pollinat*” returned 634 articles, 157 of which were related to this theme and included in our database

Fig. 6

Research Funding/Grants for projects related to plant–pollinator interactions or to pollinator (e.g. abundance, diversity, healthy) in urban ecosystems in countries with developed (light grey) (97.78%; N = 44) and developing economies (2.22%, N = 1) (dark grey). In light grey and hatch pattern Grants/Research Funding for Canada (US$ 299,370.00 million), the United States (US$ 2,745,636.00) and the United Kingdom (US$ 2,963,526.00)—together they accounted for 83.67% of the investments (N = 40). For the inclusion and exclusion criteria when searching Research Funding/Grants at Dimensions Platform (2020), please see the Flow diagram in Fig. 1. Bubble color represents the number of published articles; Bubble size represents the number of Research Funding/Grants, which are informed in the box at right. This box also details the total amount of funding per country (Data source: Dimensions Platform ; https://www.dimensions.ai/)