Please do not use rope of any kind to wrap around the tree for your hammock suspension. Although the damage may not be readily visible, it will harm the inner cambium layer of the tree, worst case scenario, killing said tree...
A 1"+ polyester/polypropylene/Kevlar strap is recommended. I personally use 1.5" polyester straps, with loops sewn into one end, to hang my hammock. A local outdoor store sells the webbing for $.25/ft, so I was able to make two, 12' straps, (we have some big trees here), for ~$6...
I then simply thread the free end of the strap through the loop, tighten it against the tree, and use a marlin spike hitch, (simplest knot ever), to attach the straps to the carabiners at each end of my hammock.
Altogether this setup takes about a minute to deploy, has no stretch, and does not harm the trees at all.
I love paracord, it's a practically indispensable part of my kit, but it has no place in my hammock suspension. Tarp guy lines maybe, (a bit overkill for that though IMO), but not for hanging...