Climate change is making it harder for plants to spread seeds via animals

The loss of biodiversity of birds and mammals from human-induced climate change has reduced the ability of plants to spread their seeds via animals, according to a new study.

Published in Science earlier this month, the study uses data from more than 400 networks of seed dispersal interactions between plants, birds and mammals to track the changes being seen by declines in animal populations due to climate change.

Half of all plant species rely on animals to disperse their seeds, either through their feces or hitching a ride on feathers, wings and fur, and seed dispersal networks lost or created in new ways to make up for biodiversity loss can influence how plants can adapt to climate change through migration, the study states.

The American and Dutch researchers estimate that mammal and bird losses have reduced the capacity of plants to adapt to climate change by 60 per cent across the globe.

• Sign up here to receive The Climate Barometer, delivering climate and environmental news to your inbox every week

“We’re losing animals, but we’re also losing what those animals are doing with their ecosystems,” lead study author Evan Fricke said. “When we lose those seed dispersers, we lose these … relationships between plants and animals that support how these ecosystems are functioning.”

In order to map the seed dispersal systems, researchers used machine learning and data from thousands of field studies to map how seeds are distributed by birds and animals all over the world.

To better understand how those networks are in decline, the study then compared maps of seed dispersal networks today with maps showing what dispersal networks would look like without human-caused extinction events or restrictions on how far species can range, according to a news release.

"Some plants live hundreds of years, and their only chance to move is during the short period when they're a seed moving across the landscape," said Fricke in the release. "If there are no animals available to eat their fruits or carry away their nuts, animal-dispersed plants aren't moving very far."

The study found some regions where seed dispersal networks declined by 95 per cent, and that the most severe losses were in temperate regions across North America, Europe, South America and Australia.

If endangered species go extinct, tropical regions in South America, Africa and Southeast Asia would be most affected.

But Canada isn’t immune either.

“Blueberries and salmon berries, all the things you can think about in the understory, those rely on mammals and birds,” said University of British Columbia botany professor Amy Angert to CTV National News. “Climate change is shifting where those suitable habitats are…and that means that plans will need to move really fast and far to keep up with that.” 

With files from The Associated Press