I've had an idea about harnessing blackberries which I haven't tried but I'm pretty sure it will work...
You know those blue 50 (or so) gallon water barrels? I think if you cut the top off, then cut the bottom off and then cut the thing in half around the middle, you'd have some pretty indestructible harnesses. Of course you'd have to dig a pretty big hole to start with so you could set this thing in the ground before throwing the dirt back in and around it so you could plant. But the roots couldn't grow through them, just up and down.
Gives me an idea ... not the most environmental, but would make hidey holes for some birds ...like ducks or turkeys or free-range chickens ... make a tunnel out of tires lined up in end, plant the bottom portion to stabelize it, fill with bedding ... let the vines grow, then you can keep trimming around the front side so you and the birds can get in there. The barrels would be good for that, too, safer for sure, but not always free. Could work with blackberries, or roses (edible rose hips), too.