2 of the things that affect arrow flight from a tree as opposed to the ground are. One is gravity. There will be less of a drag from a tree causing an arrow to fly farther flatter. The second is if you have a tendence to drop your bow arm. If you do you most likely have your pins set to the dropping arm. It won't happen from a tree. Your arrow will fly higher.

Set your pins from an elevated position and you'll be good. My arm does drop and I do shoot high from an elevated stand. I know it. I would aim 2-3 incheslower if I didn't set my pins from an elavated position.

There's no substitute for practising the shots you expect to take.