Green belts are “effective” in curbing urban sprawl, according to a Montreal study
Concordia University researchers say they’ve found an « almost always effective » way to curb urban sprawl, especially in big cities.
According to their study, the development of green belts on the outskirts of urban centers could contribute to limiting the growth of urban areas in a given territory, thus reducing damage to the environment. Greenbelts are protected areas, such as forests or farmland, that surround a city and even a region where real estate development is severely restricted or prohibited.
Parnian Pourtaherian, the lead author of the study published in an academic journal Landscape and urbanismargues that these spaces would prevent the often disorderly expansion of suburbs and certain economic activities.
Using open source data, the researchers tracked the urban sprawl of 60 European cities from 2006 to 2015, half of which had a green belt. These were classified into four categories: very large cities (2.5 million inhabitants and more), large cities (more than one million), medium-large cities (500,000 to one million) and medium (96 000 to 500,000).
According to this study, 90% of cities with a green belt experienced a decrease in urban sprawl during the period considered. Conversely, only 36% of the other cities had experienced such a drop.
“We found great variability in the effectiveness of the green belt across small, medium and large cities,” Pourtaherian said. « But the difference in relative changes in urban sprawl was more pronounced in larger cities. »
Pourtaherian, who holds a master’s degree in science from Concordia University’s department of geography, planning and environment, says the method could also be used across Canada.
Ottawa and Toronto both have a greenbelt and Vancouver has a “green zone” to protect natural assets. On the other hand, Montreal still doesn’t have a real green belt, but it urgently needs one, says Pourtaherian.
Effective if well regulated
For Jochen Jaeger, professor in the Department of Geography, Planning and Environment at Concordia, green belts are almost always effective, provided they are well supervised. Their effectiveness can be compromised if they are not properly shielded or if they are too small or too narrow, he says.
« Some developers and politicians are taking advantage of the housing crisis argument to expand large housing estates and allow additional low-density urban growth, or even to remove existing protective laws, » said the study’s co-author. . “They also apply salami tactics to reduce the green belt by arguing that every little piece lost is just a ‘meaningless’ loss until there is nothing left.”
Suburban sprawl may seem to go hand in hand with population growth, but its expansion distances residents from the services offered in major centers and endangers the fauna and flora on the outskirts of cities.
“Limiting urban sprawl is crucial because it leads to the loss of green spaces and wildlife habitats and reduces the resilience of ecosystems due to habitat fragmentation, declining wildlife populations and the extinction of local species” , said Jaeger.
These effects will only be exacerbated by the climate crisis, he added, which will lead to increased spending on transport infrastructure, electricity distribution, water supply and sewage collection. Urban sprawl is also associated with increased consumption of fossil fuels for transportation and the loss of fertile agricultural land.
Avoiding the expansion of low-density urban areas into natural spaces helps maintain the benefits of these spaces – including better air and water quality – which the current generation can then pass on to future generations.