Hi all! Question for you regarding an 80-foot oak I have..... Over the

Are you sure that erosion is happening? Sometimes the root flares
"bulk up" so that the tops push above the soil line. That could look
like erosion.

I concur... leave it alone. Oak trees tend to be particularly sensitive to
changes in depth of soil over the roots, as lots of people have found when
they regrade their yard and shove some soil next to the trees. 3-10 years
later, they get to have the tree removed.
http://www.mortonarb.org/research/treeroots.html
http://www.ipm.iastate.edu/ipm/hortn...1995/prot.html

Kay