I live in Pittsburgh which has a 42% forest cover, and is so beautiful and green right now. All of the areas where the city government can plant trees already has parks, or is undeveloped land that already has wild trees on it. The lawns in the parks get used by people for a variety of purposes, so they are not going away. That means that more trees have to be planted where the most already exist, which is on private property, at homes or businesses. Municipal government just has to make it easier for people to plant trees on their property, and even subsidize it with tax credits. Non-profits like Tree Pittsburgh can help citizens to learn about, obtain, plant, and maintain trees, but unless local government has some barren wilderness they can plant trees on, this is a job for the private sector.