I have two large trees in my backyard. One is an oak and the other is an
ash. Currently the trees are surrounded by double stacked landscape timbers.
Behind the timbers, up to the trunks, dirt is piled 6-8 inches deep. I
suspect the previous owners did this since this piled dirt is the highest
points in the yard.

Here's my question. Would it be safe for the trees if I were to remove all
the excess dirt surrounding them bringing the level back to the rest of the
yard? The dirt has been there for at least five years.

Thanks
Mike