As you are mulching be sure to remove the excess around the trunks of the trees. Piling the mulch to close and to high around the trunk can lead to multiple issues. Since mulch is great at retaining soil moisture, it will also retain moisture on the trunks of trees which can lead to decay and diseases. Mulching to high will also effect root and root flare development. The root flare is an important part of a trees structure and may not develop properly, or at all, if mulched improperly. Roots will start to develop higher on the tree as well leading to more issues during drought and the potential for girdling roots.