"Eric the Red" wrote in message
...
there are some conifer trees that must be over 30 foot in height....
Am I under any legal/bye law obligation to cut the trees down to a lower
height?....
If I cut down at this time of year am I likely to kill off the trees...

No, as far as I know there are not yet any laws restricting height of trees.
Are they leylandii? If so, a tree surgeon told me that you can chop down
one-third of the height at any one time and the trees will be fine. When
the trees have recovered in a year or so, then you can take down another
third of the remaining height. This time of year is perfect to do it. Do
not cut back into old wood because the tree won't grow back. If the trees
are 30 feet high I would imagine you'd need a professional tree surgeon to
do the work -- it's a dangerous business!!