On 3 Dec 2003 05:28:50 -0800, (Dante)
wrote:

Help!!!


In doing so, I remember encountering, and severing one root that was
about 3 inches in diameter. Looking back I'm afraid it might have been
the tap root for the tree. There isn't much soil beneath the tree
itself. The tree literally sits atop a rock. The soil was deepest
where I cut the driveway.

I wish I had the foresight to preserve any all encountered roots.

Long story short I retained the excavated area with a laid up dry
retaining wall and have watched the tree grow frailer with each
passing season.

That was three years ago. What might I do to save this handsome tree?

Most trees don't have a taproot (or it declines shortly after teh tree
becomes established). You don't say how big this tree is (standard is
to measure diameter of trunk 4 feet above grade), but it does not
sound like an excessive amount of root loss.

Trees build stores of reserved energy in the form of sugars and
starches during the good times. When they face injury or stress, they
can seem fine for a time because they are using these reserves. As
stored NRG runs out, you see decline as much as 5 years later. That
does not mean your tree will continue to decline, but there is a
chance it will.

I agree that compaction of remaining roots may have been a factor here
(as may have been grade changes during construction) but I don't agree
the situation is hopeless. Vertical mulching or radial trenching are
agressive measures that can inprove soil structure. Slower but also
effective is simply adding mulch to the root zone. Pile on up to 4"
of wood chips, compost, bark, or other organic material. Be careful
not to pile soil or mulch against the trunk--the first major root
flares should be visible at the surface. Make sure to supplement
water during droughty periods and do NOT severely prune the tree to
compensate for lost roots--that adds insult to injury [well, injury to
injury). Whatever leaf producing branches you can maintain will help
the tree to replenish depleted NRG reserves and recover.

Check out the site in my sig below for more info about treatment of
trees damaged by construction.

Good luck,
Keith
For more info about the International Society of Arboriculture, please visit http://www.isa-arbor.com/home.asp.
For consumer info about tree care, visit http://www.treesaregood.com/