Large fruit-eating monkeys and birds in tropical forests have been revealed as surprising climate change champions, whose loss to over-hunting is driving up carbon emissions. This is because their seed-spreading plays a vital role in the survival of huge, hard-wooded trees.

 

Tropical forests store 40% of all the carbon on the Earth’s surface and the slashing of trees causes about 15% of the greenhouse gases that drive global warming.

 

Long-lived, thick and hard-wooded trees are especially good carbon stores, but they have large seeds that can only be dispersed via defecation by large animals. These big creatures have suffered huge losses from subsistence hunters, meaning hardwood trees are being replaced with softwood trees, which have smaller seeds but store less carbon.

 

The new research was led by scientists at São Paulo State University in Brazil and published in Science Advances. It focused on the Atlantic rainforest of Brazil, where 95% of all trees rely on animals to disperse seeds, and analyzed the interactions between 800 animal species and 2,000 tree species.

 

It found losses of large animals like woolly spider monkeys, tapirs and toucans leads to the loss of hardwood trees. These are replaced by softwood trees, whose smaller seeds (less than 12mm long) are spread by small fruit-eating marsupials, bats and birds which are not the target of hunters. The scientists estimated that 10-15% of the carbon stored in the original mixed forest is lost.

 

The scientists concluded: “Our result highlights the fragility of carbon storage service in tropical forests under the current global change conditions. Halting the ongoing, fast-paced [animal loss in] tropical forests will not only save large charismatic animals and the plants they disperse but also have effects on climate change, carbon markets, and reforestation.”

 

In November, the first comprehensive estimate of threatened species in the Amazon rainforest found that more than half of the myriad species could be heading for extinction. Among the species expected to suffer significant falls in numbers are the Brazil nut, and wild cacao and açai trees, all important food sources. (The Guardian)

 

 

PHOTO: The critically endangered northern muriqui (Brachyteles hypoxanthus), climbing in canopy in the Atlantic forest, Minas Gerais, in Brazil.

CREDIT: Luciano Candisani/Minden Pictures/Corbis.