New Scientist
Image: Mountain Vision
Motorists are not the only ones to benefit from high-speed roads. Life in the fast lane also helps plant seeds travel far from home. So say Moritz von der Lippe and Ingo Kowarik of the Technical University of Berlin, Germany, who have shown that traffic may account for up to half of seed dispersal near motorways.
Seeds may stick to vehicles or be swept along in the airflow created by traffic. To find out how common this is, the researchers left seed traps deep within several long road tunnels, ensuring that the seeds collected were transported by vehicles rather than the wind. Over a year, they trapped more than 6000 seeds, from which they calculated that vehicle transport is responsible for between 635 and 1579 seed falls per square metre per year. That is roughly the level of natural seed fall in sparsely vegetated areas, suggesting that vehicle transport could double the effectiveness of seed dispersal if such areas are near busy roads (Conservation Biology, DOI: 10.1111/j.1523-1739.2007.00722.x).
Among their samples, von der Lippe and Kowarik found seeds from 39 problematic invasive species that are damaging biodiversity in some parts of the world. “Many countries, including the US, spray roadsides with herbicides,” says von der Lippe.
