Produced by a regional consortium on the environment in Brittany, France, this report describes the ecological value of woody strips encircling agricultural fields and enmeshing the countryside, their decline, and ways to incentivize their protection.
Brittany is a heavily agricultural region that also features a long stretch of coastline where urban development and expansion is ongoing. Due to mechanization and enlargement of farm fields, average parcel size has increased since the 1950s, shrinking the extent of woody hedgerow (“bocage”) between fields. Between 1996 and 2008, the total length of hedgerow decreased 12%. This change is concerning because Brittany is already one of the most fragmented and least wooded parts of France.
The report explains the value of the bocage is its provisioning of habitat, connectivity between habitats, biodiversity, erosion control, groundwater recharge, and flood mitigation. Half the population of Brittany lives in areas susceptible to flooding. Furthermore, at least five endangered animal species depend on the habitat created by the bocage. Protection of this woody network is key to remedying both problems, while also providing direct benefits to farmers, such as habitat for pest predators.
The form and shape of the bocage varies throughout the region, but can include grasses, bushes and/or trees, forming one or more layers of vegetation; and heterogenous landscape features such as berms, ditches, logs, and rocks/boulders, which create microhabitats.
The network of hedge and berms, accompanied by fields, ponds and wetlands, constitutes an important natural environment because of its heterogeneity and potential for complex exchanges. It has the particularity of being able to reach a myriad of increasingly isolated natural spaces in the heart of a changing agricultural countryside subject to ongoing urbanization. Similar to a forest edge environment, the richness of the bocage can be explained by the diversity of habitats it adjoins [OEB 2018: 8, translated].
Regulatory and incentive programs payments have sought to encourage farmers to preserve their hedgerows. However, the authors suggest that a stronger economic valuation of these linear woods is needed to protect and expand them. They suggest strategies for stimulating the market for firewood and other products harvested from sustainably managed hedgerow, where biodiversity protection is an explicit aim and co-benefit.
OEB, 2018, La bocage en Bretagne [Woods and hedgerows of Brittany countryside], Dossier No. 13, L’Observatoire de l’Environnement en Bretagne, https://bretagne-environnement.fr/bocage-en-bretagne-dossier.