The Canal du Midi is one of the oldest canals in Europe. This masterpiece of ingenuity flows along its course, defying the uneven terrain, thanks to its hundreds of engineering structures and its daring water supply system.
From the very beginning of its construction, the complex profoundly revolutionized the local environment. This artificial heritage is now an integral part of the Lauragais landscape, and its green setting has allowed the development of surprising biodiversity, to be admired and protected.
Originally, an artificial environment
Its majestic plane trees and verdant banks almost make you forget: the Canal du Midi is the work of man. Its prestigious history has its origins in an old dream: that of connecting the Atlantic Ocean to the Mediterranean Sea in the south of France, avoiding the long detour through the Strait of Gibraltar.
To overcome the many valleys and hills rising along its route, an ingenious and audacious construction program was created. The inventory is extraordinary. On the 280 km of the route, we count a total of 328 structures, among which :
- 2 dams
- 80 km of supply channels
- 1 tunnels
- 79 locks
- 130 bridges
- 67 canal bridges and aqueducts
… Became a natural space over time
From Toulouse to the Thau lagoon, the Canal du Midi stretches 240 km, passing through towns, villages, and farmland. This stretch of water, lined with plane trees and embankments, constitutes a unique biotope and an extremely rich biodiversity.
Along its entire length, over an area of around forty meters wide, the Canal du Midi welcomes numerous plant and animal species, many of which are protected. Birds, mammals, fish and reptiles come here to feed, drink, bask, move around or nest.
Varied vegetation sheltered by large trees
Over time, the Canal du Midi has developed a aquatic flora Remarkable. Algae and seagrasses make its waters green. There are around twenty species, including giant duckweed, spiral vallisneria, and helophytes. The latter serve as egg-laying surfaces for dragonflies.
In spring, the embankments are a delight for lovers oforchidsSeveral varieties flourish there: the purple orchid, the pyramidal orchid, the bee orchid, etc.
The Canal du Midi owes its majesty above all to its large trees. Willows were the first trees planted, as early as the 17th century, to strengthen the banks. Other species were subsequently planted to meet the needs of the time. mulberry trees allowed the breeding of silkworms, and the poplars for wood construction. Pins, cypress et fruit trees have long surrounded the lock houses and provided additional shade and coolness.
Colored canker, a scourge for plane trees
The long rows of plane trees go back to the nineteenth century, when the Midi Railway Company, then owner of the canal, undertook a major planting campaign.
The dominant species of the banks, these trees have been affected since 2006 by the colored canker, a disease caused by a microscopic fungus. The disease only attacks plane trees. It penetrates through wounds on the roots, trunk, or branches, and can kill the tree in 2 to 5 years.
Without knowledge of a treatment, infested plane trees are being cut down and incinerated in large numbers to stop the spread of the epidemic.
75% of the 42000 plane trees on the banks have been cut down.
A vast replanting program.
The planting new trees is undertaken by VNF, with the support of local communities. The choice is towards trees resistant to canker stain and a greater variety of species. turkey oak is the most widespread new species. It will eventually represent 40% of the linear area. It is accompanied by around ten other species of tall trees.
Who populates the canal?
Coming from the rivers that feed it, many fish find refuge in the Canal du Midi. The latest inventories count more than twenty species.. The most common fish are carp, the pikeperch, the perch, the pike et the black bass. Other aquatic species inhabit the area, such as some mollusks (freshwater mussels, corbicules, etc.), batrachians and reptiles. The viperine snake, which despite its name is neither venomous nor dangerous, is a choice host. This small snake, an excellent swimmer, is one of the protected species found in large numbers in the Canal du Midi.
While walking along the banks, we are used to coming across many birds. ducks are omnipresent. Grey Herons, geese et water hens also populate the banks. They are also a dream hunting ground for great tits. Processionary caterpillars are a choice delicacy for their chicks. At night, the owl and owl wake up to hunt their prey (insects, worms, lizards, frogs, rodents and small birds).
Small mammals also like the place. The trained eye can easily distinguish burrows from nutria to muskrats. Many protected species hide in the trees and tall grass. We can see red squirrels, otters, hedgehogs, and the amphibious vole, a species protected since 2012 in France.
To learn more…
In partnership with local authorities and territories, VNF (Voies Navigables de France) has created this awareness document on the canal's biodiversity, and especially the steps taken to preserve it.
How can we preserve this biodiversity?
Alongside the plantation restoration project, numerous initiatives are being undertaken to protect this area and compensate for the damage caused by human presence:
- Species inventories and identification of cavities and nesting sites before each pruning or felling
- Installation of artificial nesting boxes for birds and bats
- Optimization and modernization of hydraulic management
- Water quality monitoring
- Cleaning the banks and collecting waste
