In an attempt to placate the majority of Brazilians opposed to the new Forest Code, Ms Dilma has blocked 12 parts of the new law and added 32 modifications.
But environmentalists and other analysts say it is unclear what impact the veto will have on illegal timber harvesting in Brazil.
"President Dilma’s vague delivery of vetoes and modifications to the new Forest Code leaves the people of Brazil without any assurances that the Amazon will be protected," said Paulo Adario, Greenpeace Brazil’s Amazon campaign director. "Instead of trying to avoid the worst parts of a bad new Forest Code, President Dilma should instead be looking for a law that actually protects Brazil’s forests."
The existing 76-year-old Forest Code was the primary legal instrument protecting Brazil’s forests, including the Amazon rainforest. The new code could potentially open up more forest to large-scale agriculture.