Trends in bee communities of shrinking cities from taxonomic and functional perspectives
The effects of urban shrinkage, in cities experiencing a large decline in population, represent a relatively new research challenge. Of the 370 cities identified as shrinking worldwide, having lost >10% of the population overall, or losing inhabitants at a rate >1% per year, approximately 25% are located in the United States, with many along the rust belt. Relatively little is known about the basic ecology of organisms that inhabit the urban core of cities that have experienced such extensive depopulation.
Of particular interest are organisms that also provide ecosystem services, such as bees. Human population decline in the urban core has created novel ecosystems that represent potential sites for pollinator conservation. Abandoned buildings could provide cavities for females to nest. Newly open spaces or unmown fields could provide forage habitat, as typical urban-exploiting plant species such as clover and various asters are highly attractive to bees. We identified shrinking cities with bee survey data and investigated bee alpha and beta diversity from taxonomic and functional perspectives.
We found urban bee communities of shrinking cities to contain diverse and abundant bee populations. Bee species collected in these sites include species representative of high quality habitat, including cleptoparasitic and specialist foraging species, but also high proportions of exotic species.