Motorway Verges Benefit Biodiversity

New research published in Biological Conservation suggests that strips of land alongside motorways play an important role in maintaining plant and spider diversity within intensive agricultural landscapes.

The research was conducted along one 50km stretch of Motorway near Paris, collecting data from 25 individual sites. Where possible, sites with hedgerows were selected within 1.5km from sites without hedgerows.

The researchers found that hedgerows were positively associated with plant diversity - being twice as rich as the grass verges (without hedgerows). Spider diversity was closely associated with proximity to natural woodland, with little significant difference in diversity between hedgerows and grassland. Spider community structure differed between habitat types; hunting and ballooning spiders were found more often in open grassland, whereas web-building and 'non-ballooning' spiders were most common in hedges.

Future research may benefit from looking at strips on different motorways in comparable landscapes rather than replicating along the same stretch of motorway. However, this preliminary research is important in that it has shown that the means in which motorway verges are planted and managed can increase plant and insect diversity in different ways.

After construction of future motorways, some restoration can be achieved by creating a mosaic of hedges and grassland, providing spatial and temporal refugia for biodiversity as well as increased ecological connectivity.

Full reference: Le Viol, I., Julliard, R., Kerbiriou, C., et al. (2008). Plant and spider communities benefit differently from the presence of planted hedgerows in highway verges. Biological Conservation. 141(6): 1581-1590.