Half of all species of plants rely on animals Spread their seeds through hitchhiking in scat, fur, or beaks. As animal populations decrease, so does the ability of plants to disperse seeds and adapt to climate change. The backdrop of a warming planet means that species are changing from their historical climate adaption. Reports say that threats like poaching, deforestation and urbanization are causing declines among mammals and bird species. This can scatter seeds and help plants get into more livable zones. Scientific American’s Andrea Thompson.
This month’s study was published in the journal Science found that 60 percent of all plants globally are already having trouble keeping up with climate change as seed-spreading species face major drops in population numbers. The study reveals the importance of larger animals carrying seeds long distances, and the impact wildlife declines can have on the symbiotic relationships. New Scientist’s Adam Vaughan reports.
“That should certainly be ringing alarm bells,” says study author Evan Fricke, an ecologist at Rice University, to Science’s Erik Stokstad. “At the same time that we’re ‘forcing’ plants to move these great distances, we’ve also substantially slowed their ability to do so.”
Previous studies on seed-dispersal focused on specific threats to ecosystems such as tracking. How Brazil is losing bird habitat has impacted trees’ abilities to spread their seeds. However, similar data has never been analyzed on a global scale, per Scientific American.
To see the impact globally, the team gathered data on 302 animal species and the seeds each animal is known to disperse. They also collected data on how far seeds travel, how long they can survive after being absorbed and expelled from animal feces. New Scientist reports. Researchers used machine learning and modeling to fill in missing data for all animal and plant species. The model allowed the team to predict mutualistic interactions between plants and animals for rare or extinct species.
Researchers created an index to determine how many seeds could be spread over a distance of more than one kilometer by a certain number of birds or mammals. The team discovered that seed dispersal is declining at alarming rates after analysing the data. Mammal and bird losses cut a plant’s ability to adapt to climate change globally by 60 percent, per the study.
“We found regions where climate-tracking seed dispersal declined by 95%, even though they’d lost only a few percent of their mammal and bird species,” Fricke says in a statement.
Because these areas have lost many fruit eating mammals, the loss of plant resilience was even more severe in temperate areas like eastern North America. Science. Whereas mountain environments that vary in elevation feature different ecosystems within tens or hundreds of kilometers apart, animals living on flat terrain in temperate climes have to travel further to find new habitats, per Scientific American.
The data model was used to determine what would happen if endangered and vulnerable birds and mammals were extinct. The most severe losses were seen in Southeast Asia and Madagascar. These regions have a high proportion of threatened species responsible for seed dispersal. Scientific American reports. Based on this prediction, a plant’s ability to adapt to climate change would be reduced by another 15 percent on average, Science reports.
For possible solutions, the researchers suggest strengthening biodiversity by reintroducing large animals to their original ranges or connecting patches of habitat with restored areas using wildlife passages.
“Animal biodiversity supports climate adaptation for the world’s plants,” says Fricke to New Scientist. “This is a really clear intersection of the biodiversity crisis heavily impacting the climate crisis.”