Believe it or not....
A powerful enough string trimmer that will push the .105 line I was talking about.... Does fine for blackberries at my house.
A small string trimmer won't do it.
I would never bring a bobcat in on top of my garden.... Doesn't matter how many thorns are growing....
And.... I know a thing or two about thorns here....
This wheelbarrow of smilax tubers came from a single clump....
A string trimmer is useless against greenbriar and mature grapevines.... The chainsaw is necessary with those.... Afterwards the mattock is well suited for getting those roots... Just gotta go after them when the ground moisture is optimum.
A bobcat is positively going to damage everything.... Packs soil around the tree roots, driving all the oxygen out of the soil.... You'll be spending as much time trying to repair the damage to the soil that you hoped to save by bringing in the equipment in the first place!
And..... Nothing is going to get all the blackberry roots the first time through.... But... They are generally near the surface of the soil, so.... Once the briars are down, the roots are easily dug out with a mattock....
