Both intrafascicular and interfascicular cambium joins together and forms a cambium ring. The periclinal division of vascular cambium ring forms secondary phloem (outside the vascular cambium) and secondary xylem (inner to vascular cambium). The primary phloem is crushed to death, known as obliteration. Primary xylem being dead and lignified, replaced in the pith region.  

Removal of ringwood outside the vascular cambium kills the tree because the phloem gets removed and the food synthesized in the leaves does not move to different parts of the plant.