Post-industrial cities often have large numbers of vacant lots, left behind as people have moved out of the area. Local residents are often tempted to plant wildflowers to make these deserted spaces more attractive.
Wildflowers are an important food source for bees. Pollinators like bees play a vital role in food production and attracting them with food sources is a good idea. However, a study by researchers at the University of Cambridge in the UK found that there are dangers associated with planting wildflowers in some urban settings.
Wildflowers growing on land previously used for buildings and factories can accumulate lead, arsenic, and other metal contaminants from the soil. These metals have previously been shown to damage the health of pollinators that ingest the metals in the nectar as they feed.
The Cambridge study was carried out in Cleveland, Ohio, which has nearly 34,000 vacant lots. Cleveland was previously the site of iron and steel production, oil refining, and car manufacturing. The researchers tested the nectar from flowering plants growing on disused land throughout the city. Lead was the contaminant found in the highest concentrations. They also found that different species of plants accumulate different amounts and different types of metals.
The goal of the study was not to discourage the planting of wildflowers in towns and cities. It is to highlight the importance of growing the right species of wildflowers as well as to encourage testing soils for metals before planting wildflowers and to clean up pollution. Wildflowers are important for pollinators, but it is also important that they don’t contribute to the decline of pollinator populations that has already been happening for a number of reasons.
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Growing wildflowers on disused urban land can damage bee health
Photo, posted August 26, 2012, courtesy of RJP via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
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