I grabbed onto grape vines with the backhoe and thumb. Then drive forward while swaying the boom back and forth. Must have looked like a dinosaur ripping it apart. I lost traction a few times but ultimately prevailed.
Lordy - looks like you are attacking a jungle. I have 80 acres. I have ancient Ponderosa pines. The only other "stuff" - bunch grass and Buck brush. Buck brush will max out at two feet high and big around as your yellow lead pencil.
I agree grape vines are tuff. Have lots of them. Some ancient ones almost big enough to mill for lumber!! Always have to be careful if you snag one what they can bring down on you. Tenacious tendril rascals love to wrap around axles, grab undercarriage and eat auxiliary light fixtures.
I had poison ivy vines like that. I found the base of vines and sawed them off. I then sprayed the base with glyphosate/24d. I wasn't in a hurry to get them out of the trees. After a couple years you could hardly tell the vines had ever been there.