At our club observatory located about 50 to 60 miles north of New Orleans, we cleared some land on a lease back in 1994/95 to create our observing field. At that time we could easily see Polaris from where we typically set up. Our west probably had a horizon down to about 7 to 10 degrees, our south to about 15 degrees, and our east to about 18 to 20 degrees. We have had trees (mostly pine) topped before and we have even removed some trees. About 12 or so years ago we even created an "Omega Notch" so that we could see Omega Centaurus in the spring. (Max height from our location for Omega is about 12.2 degrees above the southern horizon.) Today, our horizon to the north is probably 27 degrees above the true horizon, toward the west we can probably only see down to about 20 degrees above true, maybe 25 degrees to the south and 30 degrees to the east. Our sky window is getting smaller.
The "Omega Experiment" showed just how much cutting a lower opening exposed us to light pollution to our south. (On the best of nights our limiting magnitude is about 6.1 magnitude at the zenith, but readings at the horizon fall off and that opening was noticeably brighter than the rest of the sky.
In addressing a new member's query about why we didn't or when will we cut/trim trees, I got to thinking about just how much of a difference a higher mounted tube assembly (think refractor) might make in allowing you to see some tree skimming objects when you have a situation like ours. (the cleared part of our property is about 1 acre in size) Think about it, if the RA axis of a refractor (or schmidt-cass or Mak) sits about 2 feet above the RA axis of a newtonian reflector or the altitude axis of dobsonian reflector, how much of a difference does that make? Without considering angles or distance it would make a two foot difference if say Polaris was at tallest tip of a pine tree in a reflector, and above that in a refractor. The pine tree would have to have another season or two of growth to effect the view of Polaris in the same way, if viewing is done thru a refractor. The height advantage of the refractor on a taller mount becomes more of a factor on smaller observing fields. Something to ponder.
Here is a photo of our field.