Another way to get rid of the ones you want to use for firewood is to girdle them. Run the chainsaw around the trunk in 2 circles 1-2" deep, and if you want to be real sure also douse the girdles in herbicide. For some reason girdling usually keeps black locust from root and stump sprouting. If any of them are 12" diameter (not around) or more, cut them at least 8' long and get them to a sawmill. Black locust is beautiful wood, and they also make great dimensional lumber for exposure to moisture and the ground.
