Big animals spread the biggest seeds, which in turn grow into the biggest trees. Some seeds are spread exclusively by animals. This means that a decline in the number of large animals can cause reductions of up to 60% in the abundance of the tree species they disperse.
We rely massively on these trees to store carbon. Rainforest leaves suck in carbon dioxide from the air. The trunks, roots, and soil beneath them represent a store of up to half the world’s carbon.
Cool Earth is all about working with local people to keep trees standing and keep carbon locked in. And recent research1 shows it’s just as important to protect the large animals that call the rainforest home.
The effect that animal loss has on carbon storage is biggest in the Amazon, Africa, and South Asia, as there are more tree species that are dispersed by animals. The researchers estimated that if half the large animals were lost, 5% of the aboveground carbon stock would disappear. If all the large animals were lost, that figure rises to 12%. Across Cool Earth’s projects, that would equate to over 24 million tonnes of CO2.
88% of the world’s tropical forests face losing their large animals through the combined effects of hunting, habitat loss, logging and other threats like mining. Animals that disperse large-seeded tree species are the most vulnerable to these threats. That’s because they need more food, and have larger ranges than smaller animals so are often the most hunted.
Given the fact that large trees contribute the most to above ground carbon stocks, protecting the animals that disperse their seeds across the tropics is vital for climate regulation.