One way to preserve the trees that are the essential green infrastructure of a community is through tree preservation ordinances. These laws guide preservation, protection, maintenance and replacement of a community's trees. They also can can protect the public from trees which pose a threat or danger due to disease or hazard conditions. The Community Trees Program of The Morton Arboretum can help with drafting such ordinances.
Tree Ordinance Guidelines from the International Society of Arboriculture
Guide to Writing a City Tree Ordinance from Louisiana State University