Pruning

Pruning involves cutting tree branches to ensure a safe clearance around medium-voltage lines. Pruning is mainly carried out in developed environments (cities, suburbs and villages). This method causes the least disturbance to vegetation, thereby helping preserve natural habitats and protect biodiversity.

However, pruning is a difficult, dangerous and costly operation that must be repeated regularly (every 3 to 6 years). Cutting branches before they get too close to medium-voltage lines is an enormous, never-ending challenge since some tree branches can grow two metres a year. Another disadvantage: a pruned tree loses its natural shape.

How it works

A tree trimmer hired by Hydro-Québec prunes and picks up tree branches.

For non-ornamental trees, such as roadside woods, the clearing width is greater and the residue may be left spread over the ground or in small piles to encourage biodiversity.

There is no cost to the owner of the tree.

Every year, Hydro-Québec prunes trees along nearly 150,000 spans (a span is a section of an overhead line between two
neighboring poles). This is an enormous, never-ending task that we can all make easier by choosing trees that won’t grow
too close to medium-voltage lines.

Clearing

This approach is reserved for forested areas. Clearing involves cutting all trees down to ground level while maintaining low-growing vegetation that will not come too close to medium-voltage lines. This vegetation control method preserves a diversified plant cover that provides habitat for various animal species.

Clearing is carried out every 6 to 12 years.

Every year, Hydro-Québec clears over 20,000 spans (a span is a section of an overhead line between two neighboring poles).

How it works

A qualified cutter hired by Hydro-Québec cuts down the trees and may (or may not) pick up the residue. Residue can be transformed into chips (with or without recovery), left spread over the ground or put in small piles to encourage biodiversity. There is no cost to the owner of the tree.

Wood and branches left on the ground

Residual wood and branches have a role to play in preserving biodiversity. This residue, chipped or left as-is, can be scattered over the ground. When it decomposes, it provides some of the organic matter that is so necessary for Québec soil, given our short decomposition seasons and cold temperatures.

Piled into small mounds called windrows, the residue provides long-term habitat for wildlife and invertebrates.

Dead wood from large-diameter trees promotes the germination of certain plant species and plays a role in water retention and erosion control.

A strip of land beneath a power line where selective clearing was carried out. Small mounds of wood, or windrows, are visible at the edge of the cleared area.
The white-throated sparrow (Zonotrichia albicollis) is one of the bird species found in distribution line rights-of-way. Thanks to the implementation of biodiversity measures, this sparrow can find food and refuge and even nest in the rights-of-way.

Snag preservation

Snags are the trunks of dead or dying trees that are still standing. They play a key role in our ecosystems since dead wood is a boon for mushrooms and insects. Over time, these organisms create cavities where small mammals take refuge to give birth or protect themselves from predators. In this way, snags provide shelter for a wide variety of species: mushrooms, plants, invertebrates, birds and small mammals. Hydro-Québec therefore recommends keeping them as long as stringent safety criteria are upheld.

Preservation of a small fir tree snag after clearing work under a distribution line.

Cutting down weakened trees

Trees that show signs of structural weakness (partially uprooted trees, trees damaged in a storm, etc.) and are in danger of falling on distribution lines are cut down.

The first step in planning this operation is identifying at-risk trees. This complex task is carried out only by arborists.

A Hydro-Québec forestry engineer evaluates the mechanical strength of an eastern white cedar
that has a long crack and presents signs of decay on its trunk.

How it works

An arborist hired by Hydro-Québec cuts down the trees and may (or may not) pick up the residue. Residue can be transformed into chips (with or without recovery), left spread over the ground or put in small piles. Commercial timber is not chipped, but left as is for various uses (fuel wood, etc.). There is no cost to the owner of the trees.

Pruning or cutting to restore electricity service

Following a major weather event (wind, snow or freezing rain) or an accident that has resulted in outages, Hydro-Québec prunes or cuts down trees as required to restore electrical service safely and prevent further outages.

How it works

Hydro-Québec or an arborist hired by the company carries out the required work, at no charge to the tree’s owner, but does not pick up the residue. That responsibility falls to the municipality or owner.