On 7/15/2008 6:36 PM, paghat wrote [in part]:
Some city and
town regulations won't permit it, though, the "minimum of eight feet above
the sidewalk" or "twelve feet above the road" rule is common, and if you
don't due, some turds in a truck working for the city will come by one day
and butcher the tree swiftly and with no concern for how it looks.

And definitely no concern for the health of the tree.

Over a 30+ year period, the County would trim the trees growing the the
parkway on our block (Japanese zelkovas, Z. serrata). (Parkway: the
strip of landscape between the sidewalk and the street.) Through good
luck, I was always home on those days (even before I retired) and shooed
the County's crew away from my tree.

My neighbor was not so lucky and did not even care. Then, about 3-4
years ago, on a summer day without a breeze moving, I heard a crash.
Going outside, I saw that the trunk of my neighbor's zelkova had split
from the lowest branches to the ground. The result completely blocked
the street, with branch tips reaching the sidewalk across the street.

The problem was that the County's pruning efforts resulted in weak
V-shaped crotches where branches met. My own pruning efforts -- later
followed by the professional tree service that I now use -- resulted in
stronger U-shaped crotches.

A tree that shaded the south side of my neighbor's house -- very
important when summer temperatures always exceed 100F -- and was worth
several thousands of dollars was lost because of hasty, incorrect
pruning by the County.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening pages at http://www.rossde.com/garden/