Wild animals are like us: day after day, they must move to feed, reproduce, shelter and rest. But our roads, our towns and our fields are getting in their way. Consequences: natural environments are fragmented, ecological corridors are broken, connections between habitats are broken up.
Ecological connectivity is, according to biologists, essential to the preservation and flourishing of nature. This is also a crucial dimension of the Kunming-Montreal global biodiversity framework, negotiated in 2022. All countries want to improve connectivity… but none really know how to measure the progress made.
A study signed by ecologists from McGill University, published Tuesday, could change the situation.
Montreal researchers offer a simple and effective “toolbox” for measuring ecological connectivity anywhere in the world. And they demonstrate their method in an “ecoregion” well known to Quebecers: the St. Lawrence lowlands.
Result: the forests of this great plain are not losing ground, but they are becoming more and more fragmented. One of the indicators calculated by the researchers — “metapopulation capacity,” which measures the size of connected habitats that can support animal populations over the long term — fell by 19% between 2011 and 2021.
“Even if the area of forests has not really changed, their connectivity is declining sharply,” summarizes Jacqueline Oehri, postdoctoral researcher at McGill University and first author of the study. “It’s impressive, I didn’t expect the reduction to be so pronounced,” she adds.
“We observe a strong fragmentation of habitats everywhere, even where their surface area increases thanks to restoration or conservation projects,” specifies his colleague Andrew Gonzalez, holder of the Liber Ero Chair in conservation biology.
In light of this new study, Professor Gonzalez insists: a strategy dedicated only to increasing the total surface area of natural areas, but which does nothing to ensure their connection, “that will not be enough to protect biodiversity”.
In December 2022, on the occasion of COP15 in Montreal, the 196 parties to the Convention on Biological Diversity committed to protecting 30% of their territory by 2030. Quebec had made the same promise. In the UN text, the notion of “well-connected” environments comes up numerous times.
In the St. Lawrence lowlands, forests (protected or not) cover 24% of the territory. However, less than two thirds of these forests (15% of the total territory) are actually connected, reveals the analysis published this week in the journal Biodiversity and Conservation.
We are very far from the “magic rate” of 30%, points out Mr. Gonzalez. “It’s alarming,” he judges.
A tool
To calculate connectivity in the Laurentian Valley, the team chose seven species: the American marten, the black bear, the greater shrew, the common salamander, the wood frog, the crowned warbler and the barred owl. These animals, whose size and means of locomotion vary greatly, offer a representative sample of the vertebrate fauna of southern Quebec.
Next, the researchers gathered cartographic and wildlife data. They include in their calculations the minimum surface area that each species needs to live. They also consider the maximum distance each species can travel over an obstacle, such as a road or a cornfield.
The tool developed by Mme Oehri, called “Reconnect”, can be applied to any region of the world. Simply select species representative of the fauna of that country, then integrate the relevant data into the computer code offered in open access.
At the end of October, Mr. Gonzalez will present this new tool at COP16 on biodiversity in Colombia as co-chair of GEO BON, a group of more than 3,300 scientists dedicated to establishing biodiversity observation networks. biodiversity in the world.
In 2022, the Quebec biologist actively participated in the COP15 negotiations. Although ecological connectivity is explicitly part of the agreement voted in Montreal, the text does not propose any simple indicator to measure its quality and monitor its evolution.
It is therefore up to each signatory country to develop its own protocol. Already, Guinea and Colombia have approached GEO BON for help in measuring the connectivity of their natural environments. “This is the kind of thing that needs to be multiplied 196 times with all the signatory parties,” says Mr. Gonzalez.
A tool like Reconnect is useful nationally, but also locally. It lets decision-makers know where the most valuable (and most dilapidated) areas for connectivity are. “It can help prioritize efforts,” explains M.me Oehri. It is also possible to “roll the code” for any species of interest, such as the chorus frog.
Andrew Gonzalez — co-founder of the firm Habitat, alongside biologist and musician Jérôme Dupras — has been working for years to protect natural environments in southern Quebec. In 2021, he proposed a “South Plan” for this purpose, with 200 other experts. In 2022, he compiled a list of the most important ecological corridors in the St. Lawrence lowlands on behalf of the Ministry of the Environment.
According to him, time is running out to turn things around. The decline in connectivity is not linear. As roads, factories and parking lots multiply, “we end up crossing a critical threshold, and it collapses.”