The extinction of large animals from tropical forests could make climate change worse, according to researchers at the University of East Anglia.
New research published Friday in Science Advances reveals that a decline in fruit-eating animals such as large primates, tapirs and toucans could have a knock-on effect for tree species.
This is because large animals disperse large seeded plant species often associated with large trees and high wood density—which are more effective at capturing and storing carbon dioxide from the atmosphere than smaller trees, Physorg reported.
Seed dispersal by large-bodied vertebrates is via the ingestion of viable seeds that pass through the digestive tract intact.
Removing large animals from the ecosystem upsets the natural balance and leads to a loss of heavy-wooded large trees, which means that less CO2 can be locked away.
The study was led by researchers from Sao Paulo State University in Brazil, in collaboration with UEA, the Spanish National Research Council (CSIC) and the University of Helsinki, Finland.
Prof Carlos Peres, from the UEA’s School of Environmental Sciences, said: “Large birds and mammals provide almost all the seed dispersal services for large-seeded plants. Several large vertebrates are threatened by hunting, illegal trade and habitat loss. But the steep decline of the megafauna in overhunted tropical forest ecosystems can bring about large unforeseen impacts.
Harming Hardwood Trees
“We show that the decline and extinction of large animals will over time induce a decline in large hardwood trees. This in turn negatively affects the capacity of tropical forests to store carbon and therefore their potential to counter climate change.”
The research team studied data from more than 2,000 tree species in Brazil’s Atlantic Forest, and more than 800 animal species.
They found that frugivores (animals whose preferred diet is fruit) which are not targeted by hunters—such as small birds, bats and marsupials—are only able to disperse small seeds, which are associated with small trees.
Meanwhile large heavy-wooded trees, which can capture and store greater amounts of carbon, are associated with larger seeds. And these are only dispersed by large animals.
“We hope that our findings will encourage UN programs on Reducing Emissions from Deforestation and Forest Degradation to consider faunally intact forests and their full functionality as a critical precondition of maintaining forest carbon stocks,” Peres said.
Pedro Jordano of the Spanish National Research Council said: “Not only are we facing the loss of charismatic animals, but we are facing the loss of interactions that maintain the proper functioning and key ecosystem services such as carbon storage.”
