Here are some suggestions when you are ready to add mulch to your trees this spring. If mulch is piled against a tree trunk, pull it back to uncover the base of the trunk and the root flare, when this happens we call it the volcano effect. Mulch piled against the trunk of the tree holds moisture against the trunk, this could cause root rot because moisture is being trapped against the tree trunk.
Try to mulch out to the tree’s drip line or beyond. In a forest the tree's root system is mulched entirely by the leaves that constantly drop year after year. You should try to get as much mulch around the tree as possible.