Facebook says it will begin clamping down on the illegal sale of protected areas of the Amazon rainforest on its site.
The new measures will apply only to conservation areas and not to publicly owned forest.
And the move will be limited to the Amazon, not other rainforests and wildlife habitats across the world.
According to a recent study from the think tank Ipam (Instituto de Pesquisa Ambental da Amazonia), a third of all deforestation happens in publicly-owned forests in the Amazon.
Facebook said it would not reveal how it planned to find the illegal ads but said it would "seek to identify and block new listings" in protected areas of the Amazon rainforest.