Reconstruction of the hedgerow on the Léguer basin

National Id
France_15
Summary
The Léguer River catchment is one of the most hedged areas in Brittany. However, this territory has suffered a decline in its hedgerow mesh as a result of agricultural mechanization and land consolidation operations. Faced with the degradation of the Leguer's water quality observed in the 1990s, elected officials in the Leguer's watershed became aware of the need to preserve the hedgerow to stop this degradation, and to consider its restoration to improve water quality. Since 1999, the Leguer's watershed committee undertook awareness-raising of the watershed population, before experimenting with the restoration of hedges and embankments in several pilot basins. This work was then extended to the entire watershed, leading to the restoration of 300 kilometers of hedges and embankments. This action is still ongoing today, and aims in particular to ensure the sustainability of existing linear thanks to urban planning tools and the promotion of hedged farmland.
The in-depth description of the case study
Location description
The Leguer is a coastal river of the Côtes d'Armor that flows into the Bay of Lannion, and whose basin has a historically dense hedgerow mesh. Hedges and embankments are distributed heterogeneously throughout the watershed and are threatened in several sectors by changes in maintenance practices and the gradual disappearance of certain linear areas.
In Bretagne, 80% of drinking water comes from surface water pumping, which makes this resource fragile and sensitive to diffuse or point pollution. Several water intake points were closed in the mid-1990s due to significant water quality degradation. Due to the positive influence that hedgerow can have on the quality of surface water, policies for the preservation and restoration of hedgerow have emerged in BrIttany.
NUTS Code
Bretagne
RBD code
FRG-La Loire, les cours d'eau côtiers vendéens et bretons
Transboundary
0
NWRM(s) implemented in the case study
Longitude
-3.3920
Latitude
48.5865
Light or indepth?
In-depth
Monitoring parameters
The project does not implement monitoring of the flow and water level of the Leguer.
Study of a pilot sub-basin
In the 2000s, the Comité du Bassin Versant du Léguer (CBVL) conducted a study of the Kervulu watershed (pilot basin) to assess the effect of hedgerow restoration and changes in practices on water quality.
Physico-chemical and chemical monitoring
A water quality monitoring network on pesticide parameters has been implemented since 2007, in addition to the existing monitoring network (WFD network).
Biodiversity monitoring
The Leguer hedgerow project, led by INRA (UMR BAGAP), aims to evaluate the role of the hedge as a shelter for auxiliary fauna, both through the in situ assessment of hedge biodiversity at the hedge and farm levels, and through the analysis of the ecological connectivity of the landscape and the establishment of ecological networks in planning documents.
Performance impact estimation method
Catchment outlet
Performance impact estimation information
A pre-configuration study was conducted to assess the effect of hedgerow restoration and practice changes on water quality.
Project scale
Large
Project scale specification
The project is covering the entire Léguer river basin and specific research were conducted on sub-catchments.
Application scale
River Basin
Installation date
1999-2019
Area (ha)
50 000 ha
Area specifications
300 km of planted or restored hedges and embankement
Favourable preconditions
The planting of hedges helps to fight against erosion and improve the quality of surface water. The many co-benefits of this measure have contributed to the progressive extension of the restoration program to the entire watershed.
Design authority
Authority type
Other
Role
Initiation of the measure
Responsibility
Responsible
Name
Lannion Trégor Communauté (LTC)
Comments
this is a mutli municipality administration, common organisation in France to gather resources to manage technical topics such as water, waste and other topics.
Authority type
Local water authority
Role
Initiation of the measure
Responsibility
Responsible
Name
Comité bassin versant du Léguer (CBVL)
Key lessons
The area was primarily the subject of consolidation actions to increase size of fields by agriculture authorities. This led to an important destruction of hedgerows and some farmers were therefore reluctant to replant hedges shortly after. The fact a wood energy sector using wooden chips elaborated using recovered wood from the maintenance of hedges has helped convince local stakeholders to engage at such a large scale. Almost 300km of hedgerows and embankments have been restored in the basin. A reduction of chemical and nutrient pollution has been found. the research conducted showed the habitat role of hedgerows for agriculture auxilaries, made possible in oparticular with a diverse and good stratified hedge. The project has created a common dynamic towards preservation and restoration of hedges and embankment beyond farmers, including citizen and elected officials and created a territorial identity. The project leader underline is important to watch not only the increase of the hedgerows but also their maintenance.
Success factor(s)
Success factor type
Financing possibilities
Success factor role
main factor
Comments

The emergence of the wood sector (grove wood, production of wood chips to supply boilers) has been a real opportunity for farmers to find an economic interest. The gradual structuring of an energy wood sector allowing the valorization of wood from the maintenance of hedges in the form of logs or wood chips has helped convince the territory actors commit themselves on such a scale. Finally, the project benefited from the regional dynamics linked to the Breizh Bocage scheme.

Financing
Financing type
Local funds
Barrier
Barrier type
Attitude of relevant stakeholders
Barrier role
secondary barrier
Comments
Some farmers were reluctant to plant hedgerow lines soon after participating in land consolidation actions.
Policy description
The Léguer River is labelled a Wild River. Its catchment area is one of the most hedgerow territory in Brittany, with an average 150 meters of hedge per hectare. However, this hedgerow has been gradually eroded as a result of agricultural mechanization and land consolidation, as well as the phasing out of hedge and slope maintenance seen as a cost without any benefit. This decline was estimated at a loss of 3 linear meters per hectare per year.
The main objective of the project was to improve water quality and control erosion. Limiting runoff allows water to stay longer before reaching the watercourses, giving time to natural processes to occur to purify the water by soil microorganisms or light.
Secondly, the restoration of hedged land is of interest for biomass supply, biodiversity conservation, carbon sequestration, renewable wood production, for the wind-breaking role of hedges, livestock protection and landscape restoration.
Policy wider plan
Wider plan type
Regional
Wider plan focus
Environment & Biodiversity
Name
"Breizh bocage"
Comments
The programme aims at the Brittany region level to enhance protection and restoration of hedgerow landscapes.
Hydrological effects
The hydrological response to rain event seems longer than river basins with no action on hedgerows. Farmers also report complete stop of mud flows in lower areas of the fileds which were previously common problem.
Information on Water quality overall improvements
The study carried out in the Kervulu basin showed that the sub-basins that had been the subject of restoration of the hedgerow coupled with the adoption of rationale weed control practices contributed less to pollution (in particular phosphorus and pesticides) of surface water than the other basins.
Since the 2000s, an improvement has been observed on the nitrate parameter, while it was increasing in the 1990s.
Information on Reducing flood risks, quantity
During floods, it was observed that the hydrological behaviour of the Leguer appeared less reactive than that of other nearby rivers that had not been the subject of such a restoration program.
In addition, farmers report that they have noticed the disappearance of mud flows on the lower part of their fields following the creation of hedges that break the slope.

Partners

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