With the big animals gone forever, climate change could get worse, according to a new study.
The University of East Anglia research 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.
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.
Carlos Peres, from UEA's School of Environmental Sciences, said that 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.
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Peres added that they 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.
He noted that they hope that the findings will encourage UN programmes on Reducing Emissions from Deforestation and Forest Degradation (REDD+) to consider faunally intact forests and their full functionality as a critical precondition of maintaining forest carbon stocks.
The study is published today in Science Advances.