This story about a researcher at my university included this line:
...in recent years global retailers like McDonald’s and Wal-Mart have committed to removing beef and soy produced on deforested land from their supply chain. In turn, commodity traders – companies like Cargill that buy agricultural goods – have put pressure on local producers to follow suit.
The article mentions the difficulty in actually ensuring that no beef or soy comes from deforested land (including the interesting concept of "cattle laundering"), but assuming McDonald's et al are mostly successful: what happens to the farmers?
Do policies such as this do more harm in the long run? Simply cutting off purchase of products from unsustainable farms in developing countries would seem to have drastic consequences. Are there better solutions that would involve working with those farmers, rather than just cutting them off?