In the Driver’s Seat

The airflow generated by moving cars can pick up and transport seeds, potentially helping invasive plants spread, researchers report in PLoS ONE.

Cars are already known to carry seeds in the mud stuck to their surfaces, which might explain why invasive species move so fast in areas with a lot of roads. The study authors wanted to find out if the air turbulence created by cars might also play a role.

So the researchers set up an experiment in a parking lot. First, they sprayed seeds from four species with fluorescent paint, then spread hundreds of the colored seeds in a thin strip on the ground. Next, a team member repeatedly drove a Vauxhall Astra through the lot along a 45-meter path. Finally, the researchers used an LED-UV lamp to find the scattered seeds.

Seeds with plume- or wing-like structures travelled a median distance of 8 meters, while those without such structures travelled 1 meter. Some seeds were carried as far as 45 meters, and a video showed that the airstream lifted seeds about 50 centimeters above the ground.

Seeds that fall off muddy cars might therefore get blown farther along the road by other vehicles’ airflow, the authors say. But not every invasive seed will make it: Some will probably get smushed under the cars’ tires. Roberta Kwok | 14 January 2013

Source: von der Lippe, M. et al. 2013. Human-mediated dispersal of seeds by the airflow of vehicles. PLoS ONE doi: 10.1371/journal.pone.0052733.

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