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We should not rely on retention basins built along highways or in new residential neighborhoods to compensate for the destruction of natural wetlands, but these infrastructures could still give nature a boost. This is what a study published in the journal suggests Wetlands by a team from Laval University.
“In recent years, we have seen an increase in the number of retention basins along roadsides and in new residential neighborhoods,” reports the head of the study, Monique Poulin, professor in the Department of Plant Science at Laval University and researcher at the Quebec Biodiversity Science Center. These infrastructures are used to receive rainwater in order to avoid flooding. They were not designed to resemble wetland habitats, but due to the conditions found there, plants and animals typical of wetlands can settle there. We wanted to know to what extent the plant communities that live in these basins resemble those of natural wetlands.”
To do this, Professor Poulin’s team compared the plant communities of 20 retention basins located along four roads in Quebec – the 175 north of Quebec City, the 85 in Témiscouata, the 73 in Beauce and the 367 in Portneuf – to those of 20 wetlands located near these basins and 20 wetlands located far from roads.
The results? When the analyzes focus exclusively on the aquatic part of these environments, the plant composition of the ponds is very similar to that found in natural wetlands adjacent to or distant from the road. This similarity is also observed, although to a lesser degree, in the zone surrounding the aquatic part of the three environments.
“There is an interesting plant diversity in the aquatic and riparian zones of retention basins,” notes Professor Poulin. However, these environments are not natural habitats and we should not believe that they can be used to replace wetlands that are destroyed during the construction of roads or residential neighborhoods. But, since we have to build these basins, we might as well develop them to encourage the installation of natural wetland plants.”
“These environments are not natural habitats and we should not believe that they can be used to replace wetlands that are destroyed during the construction of roads or residential neighborhoods. »
— Monique Poulin
The work of Professor Poulin’s team also led to some recommendations intended for the Quebec Ministry of Transport, the sponsor of the study. “By creating sinuous banks around the aquatic zone of the basin rather than a regular bank and by reducing the slope of the embankment, we would significantly increase the surface area on which wetland plants can settle,” suggests Professor Poulin. We could also use these environments as nurseries to grow plants that could be used in wetland restoration projects.”
Remember that more than 50% of the surface area of wetlands in the St. Lawrence Valley has been destroyed over the last two centuries and that the losses have accelerated in recent decades.
The other signatories of the study published in Wetlands are Pierre-Alexandre Bergeron D’Aoust and Mathieu Vaillancourt, from Laval University, and Stéphanie Pellerin, from the Plant Biology Research Institute of the University of Montreal.
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