On the root that leads outside of the tree trunk, walk about halfway back to the sand dune and look to the left (as you're facing away from the tree). There is a small outcrop on which you can drop. --- PSN: Therinlahhan
If its that one middle tree along the way to the dragon covenant, you actually have to drop off the root path into a hollowed out part that ramps up to it. Definitely be careful though cause I died 3x doing that from the stupid camera angle.
At least there's that bonfire at the start of Ash Lake.
Go outside to the side that's facing the the Stone Dragon area. You will be walking on a root/branch thing. Say like halfway, stop, move camera below you, you should see a hollowed-out giant tree trunk. Carefully drop down into. Take that route to your loot.