A complete ring of bark cut from round the circumference of a tree-trunk causes the tree to die. ...

The xylem is the living parts of the transport system on the outside of the tree, so cutting a ring deep enough will disrupt the xylem and the tree will receive no nutrients,

This method of removing a ring of bark cut from the tree trunk is called 'scarring'

This makes the tree vulnerable to disease, and although the xylem continues to live and carry water and salts to the leaves, it cannot absorb any more nutrients because the phloem (a protective layer made up of tiny tubes that transport the sugars from the leaves to the rest of the tree) is severed, so the leaves can perform photosynthesis...but the sugars cannot reach the tree

- its as if our intestine malfunctioned, we can still eat, and transport food to the stomach and mechanically digest it, but if the ileum (a part in the small intestine) malfunctions, we can't absorb the nutrients and send them around our bodies

that little waffle isn't needed in your answer, but it might help you to understand better

Hope this helps

When you remove the bark,you are actually removing the phloem... And as the food cannot reach to the roots from the leaves,root start to consume the stored food but soon dies. As the result water and mineral transportation stops and plant dies...

sorry,
but your question is wrong....
once you cut a layer from something(plant.tree....)
the xylem carrier's route is blocked....
then how will the tree survive..........?