Cuz they are imbedded deeply in the ground and only a few inches stick up? That's what I have an acre or so of, below the area that has been finished as lawn. If you were to bring your pick and shovel, you will find that many are too large for even several persons to pick up, if you cared to spend days digging around them. Obviously OP doesn't care to take on a large land clearing project with heavy equipment, but is only trying to keep the brush under control.
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