The tropical rainforests of Africa and Asia play a crucial role in keeping our planet healthy. They moderate our climate, absorb the carbon we produce, and act as a major source of atmospheric moisture – which can fall as rain many miles away.

One of the biggest tropical forests in the world is in Congo. Its huge size and incredible biodiversity is partly thanks to an unlikely ally – the elephant.

In this film, The Nature Conservancy’s lead scientist Dr M Sanjayan, Dr Valerie Kapos of the UN Environment Programme, and tropical field biologist and conservationist Dr Ian Redmond reveal the crucial role that elephants play in keeping these forests strong and resilient, and how elephants are the most important player when it comes to the diversity of tree species in the rainforest.

If you would like to comment on this, or anything else you have seen on Future, head over to our Facebook or Google+ page, or message us on Twitter.