Chlorofluorocarbons are a class of organic compounds that were used as propellants in the late 20th century. The problem with CFC's is that they attack the ozone layer, breaking it down. The weakened ozone layer is not able to stop UV light from reaching the earth, so the amount of UV light reaching the earth increases. This results in increased temperatures, and the death of vegetation.
More simply, it effects the growth of vegetation throughout the globe by increasing the ultraviolet light on Earth’s surface, which will consequently then raise temperatures and decrease plant populations.