When this first layer (phloem) is exposed by the removal of bark, it sets off a chain reaction. The phloem transfers the nutrients from the photosynthesis process generated by the leaves.

When piled against the trunk, mulch cuts off necessary air circulation, causing inner bark (phloem) death — also weakening the roots. Avoid bark suffocation by keeping mulch at no more than two ...

Though the tree appeared to be thriving, its phloem, the fibrous layer under the bark that transports nutrients, was dry and brown. Six moved to the next tree, another seemingly healthy one.