I've been keeping a circular area of my backyard clear of snow under a
maple tree by using a snow blower to concentrate the snow closer to the
trunk of the tree. I've probably gone overboard doing it. The pile is
roughly 4 feet in radius and about 5 feet high. Now because this is
snowblower-blown snow, it becomes more dense when it's piled up, so this
is becoming quite a heavy and dense pack of snow. The tree is about 18
- 20 inches diameter at the base, and about 12" diameter at the level
where the snow is currently piled up. This is a sugar maple, if that
matters, and (naturally) there is no road salt or other chemicals in the
snow.

The canopy of this tree (and hence it's roots) extends far beyond where
the snow has been piled up, so I don't think that oxygen availability
will be an issue.

I'm wondering if this snow pack can cause any harm to the bark of the
tree - perhaps not for the next month or so, but come april if the snow
pack is still in contact with the trunk. This tree doesn't really leaf
out until early may, if that's a factor.

Along the same lines, there are 3 shade-master locusts in the circular
boulevard of our court. Their trunks are 3 to 4 inches in diameter.
The circle is 50 ft diameter and is currently covered with an average of
about 2 feet of snow-blower-blown snow. So these trees also have snow
packed around their trunks. There is no salt used on our court - only
sand, and only occassionally.

So my question about snow packed around tree trunks applies to those
trees as well.