Widespread Hedge Removal in France Has Profoundly Changed How Rain Penetrates Soils

What if uprooting a single hedge could alter the course of thousands of litres of water? Since 1950, France has lost 70% of its hedgerow network. Behind this dramatic disappearance lies a much less visible transformation: the path rain follows as it soaks into the soil.

In a few decades, France has dismantled a colossal living architecture

After World War II, the French countryside enters the tractor era. Small plots bordered by banks and hedges become cumbersome for machines. Land consolidation then brings fields together and straightens the lanes. Little by little, it erases this old rural puzzle. The hedgerow landscape recedes, often in the name of a more productive agriculture.

The scale is still surprising today. According to the CGAAER, an agency attached to the Ministry of Agriculture, about 70% of the hedges present in 1950 have disappeared. And the movement is not just about the past. Between 2017 and 2021, the net loss would have reached about 23,500 kilometres per year.

Under the branches and roots lay a discreet system for slowing water

A hedge is not simply a plant boundary set at the edge of a field. Its roots, the vegetation at its base, and sometimes the embankment form a special zone. Water meets more obstacles there. The runoff slows and the soil has more time to absorb part of the precipitation.

This mechanism may seem modest over a few meters. Yet, repeated across thousands of plots, it alters water movement at the scale of a watershed. INRAE also highlights the hedges’ role against soil erosion. They can limit the transport of soil, phosphorus, or residues toward rivers.

However, their effect is not magical. It depends on slope, soil, groundwater, and the hedge’s position. The water balance varies depending on the situation. Trees also consume water. But their presence often creates roughness and a root network that slows down overly rapid runoffs.

When the hedgerow landscape fades, a downpour can cross the landscape much more quickly

Imagine two plots under the same rain. In the first, several hedges interrupt the slope. In the second, the fields have merged into a vast open surface. Water can then travel farther distances without meeting an obstacle. The phenomenon intensifies when the soil is bare, compacted, or already saturated.

The consequences go beyond a puddle at the end of the field. More runoff can carry soil away and load rivers with sediments. It can also locally reduce infiltration. The landscape becomes a hydrological variable. Removing a hedge is sometimes like taking away a small brake whose usefulness becomes apparent mainly during heavy rainfall.

Replanting thousands of kilometres of hedges has become an agricultural and hydrological undertaking

The awareness eventually reached public policy. With the program “Plant hedges”, France Relance set a target of 7,000 kilometres of hedges and agroforestry alignments. By the end of 2022, more than 5,500 kilometres of plantings were planned within more than 4,000 supported projects.

Yet the problem resembles a bathtub with the tap running while the drain remains open. Plantings are progressing, but the disappearance of the existing network remains significant. The CGAAER still estimated France’s hedgerow length at 1.55 million kilometres. It nonetheless noted a continued decrease despite protection and planting programs.

Restoring a hedge is therefore not merely about putting trees back into the landscape. One must choose its location and reconnect the already present elements. One must also give roots time to transform the soil. In an era of droughts and intense rainfall, one question remains: how many hedges will have to be rebuilt to make our countryside more permeable?