Hedges: climate soldiers

August 6, 2024

- Sarah Chassany and Gaétan Pique

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Since 1950, 70% of hedgerows have disappeared, i.e. 1.4 million kilometers. Despite planting programs, the surface area of hedges and tree lines in mainland France is declining.

In April 2023, the French Ministry of Agriculture released a report: several thousand kilometers of hedgerows are being removed every year across France. This represents an average annual loss of 23,571 km/year between 2017 and 2021. Despite the many benefits they offer, hedges continue to disappear at an alarming rate. In total, more than 205,252 km of hedgerows have been lost over 15 years. In comparison, planting programs have created only 3,000 km of hedges per year.

Yet hedgerows offer numerous environmental benefits, acting as natural solutions to the effects of climate change. They play a crucial role in preserving biodiversity and regulating the climate.

The most extensive and best-preserved hedgerows and bocages are located in Normandy, Brittany, Pays de la Loire, Centre-Val de Loire and Bourgogne Franche-Comté, according to the French Biodiversity Office. Office français de la biodiversité.

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Hedges: what role do they play in agriculture and viticulture?

Major ecosystem services

The benefits of hedgerows have been proven by INRAE: they are useful for development and production, and have a significant impact on rural areas and agricultural activity. They are invaluable for crops, livestock, biodiversity, watercourse safety, harmonizing with the landscape and diversifying production. They have many advantages: they stabilize soils against erosion, provide shelter from the wind, promote pollination, store carbon, regulate water resources and produce biomass.

A role to play in storing carbon

Hedgerows are agroecological infrastructures (AEI) which, during their photosynthesis process, capture carbon from the atmosphere and store it. In particular, they are known to store 1.2 tonnes of carbon per hectare per year*.

A low-carbon label for hedges

At the end of 2020, the "Hedgerows" method developed by the Pays de la Loire and Brittany Chambers of Agriculture, in conjunction with the Carbocage project, was approved for the Bas-Carbone label. It enables farmers to voluntarily sell their carbon credits by planting or maintaining hedgerows. A future decree provides for a 50% bonus for credits generated by projects that benefit biodiversity, thus promoting agro-ecological practices.

For example, a 110-hectare farm with 14 km of hedges could earn around €12,500 over 5 years thanks to the Low-Carbon label.

However, two concerns have been identified:

- The additionality criterion, which can put those who are already preserving their hedgerows at a disadvantage, as opposed to those who are planting new ones. - The administrative costs of project management and certification, which remain considerable.

How much does it cost to plant hedges?

Hedges are a natural way of storing carbon at a lower cost! According to the French Chamber of Agriculture, planting 100 meters of hedges costs around €1,560 for a single row, depending on the type of hedge and species. Total annual maintenance is approximately €50 for 100 linear meters.

This natural solution is often compared with other industrial carbon capture solutions (Carbon Capture and Storage or CCS), which are technologies that capture the CO2 emitted by industries, then store it permanently underground. CCS involves several stages: capture (capturing the CO2), transport (moving it to a storage site) and storage (injecting the CO2 into underground geological formations). The cost of implementing CCS depends on a number of factors, such as plant size, capture technology, geographical location, transport and storage costs, and regulations. Costs can vary in excess of €150 per tonne of CO2 captured.

Financing hedges

Aid is still available to reduce the cost of planting or restoring hedges under the Bocage et Paysage program, financed at 50% by the Region. A 70% subsidy is available if the project meets certain conditions, such as the planting of a minimum number of trees, collective work or the use of natural mulch favoring short circuits.

Monitoring hedges and their impact

Following the installation or restoration of hedges, it is important to regularly monitor the state of the vegetation (NDVI) and carbon capture.

Measuring NDVI will make it possible to monitor vegetation vigour in real time and adapt maintenance to its needs. As for carbon capture, accurate measurements can be used for carbon assessment and carbon credit purposes, as well as to justify a low-carbon and revegetation strategy.

Thanks to satellite data, Netcarbon offers precise, real-time measurements of a range of indicators linked to vegetation and soils: carbon capture, vegetation moisture, vegetation condition, etc. These data can be accessed via the Netcarbon application, enabling you to define a decarbonization strategy by simulating the impact of agroecological practices.

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