Why does tree bark swell up when it is cut?

Expert Answers
jerichorayel eNotes educator| Certified Educator
When a tree is cut, the transportation machinery of the tree is damaged. Remember that there vascular systems in the trunk of the tree: the xylem and the phloem. Xylem brings water to other parts of the plant (in this case tree) and phloem substantially sends nutrients needed by the plant in order to do its metabolic functions (such photosynthesis, respiration, etc...). Since the trunk was cut, the supply of water and nutrients stops. Although cut, the tree will continue to function thus the action of the vascular system will continue to transfer food and water in other areas of the tree. However, the food and water molecules will get stuck in the area where the cut is thus resulting to swelling.