X.O.
Are these plants that were on YOUR property? If so, they should be legally required to make restitution for the destruction of your personal property.
ETA: After your "So What Happened" I am still unclear as to whether the forsythia sits on YOUR property, or on the developer's property. If it is on yours, by all means, make your complaint to the BBB. If it is on his property, you really don't have room for a complaint. Sure, the hedge would be nice, but if it isn't your personal property, then he has the right to do with it what he wants.