Lily Cole was in Kew Gardens to launch Sky Rainforest Rescue, a three-year campaign run by broadcaster Sky and conservation body WWF.
Kew Gardens was chosen as the location because it houses a large number of different species of trees that are grown in the Amazon.
Every £10 that is donated will help to save 500 trees, and Sky have promised to match every single donation pound for pound.
Lily said: ''it's hard to appreciate the importance of the rainforest because it seems so far away but it's vital to the survival of the planet as we know it.'
The project aims to preserve over three million hectares of trees in Acre, in northwest Brazil.
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We love the stars being enviro-conscious.
Last week we told you Selena Gomez will be launching an eco-friendly clothing range, and this week we bring you Lily Cole's rainforest campaign.
We wonder who will be next...
By Maria Pierides