I live in an old gold mining town in the mountains of northern California. Blackberries are considered a ladder fuel for forest fires and must be controlled. It is often difficult to get any kind of equipment into areas that are infested with blackberries and managing them with manual labor can be quite hazardous.
Please don't laugh, but there is a guy up here that rents out his goats to clear brush and blackberries. Last year, our volunteer fire department hired the goats to clear the creek behind the fire hall. They did such an excellent job, the Board of Supervisors hired them to continue clearing the creek that ran through town. They also used the goats to clear the 7' cliff across the road from my property. The goats actually did a better job of fuel reduction than the fire crew did several years ago and cost a whole lot less ...
Yardenman, I know you probably don't know of anyone with a goat herd near where you live, but they are very, very efficient and leave less damage behind than other methods of clearing your land of brush and berries.