One of the purple-leaf cultivars of Norway Maple; an invasive alien species in your area, so if you do get rid of it, it wouldn't be any great loss. There again, maybe you should keep it, on the grounds that it is acting as a breeding ground for diseases that could potentially help control the unwanted regeneration. Resin

Back to your oak, cd: It appears to be a fine specimen. You and neighbor get along so no reason to mess that up. I'd offer to do some "raising up" style trimming, simply removing whole branches some way up the trunk, in that area, and all around the tree so as to provide for a balanced crown. But as whaas and possibly others have said, don't do it now during the growing season if oak wilt is in your area. The insect vectors of this serious oak pathogen are attracted to fresh pruning cuts. Do the pruning in the fall or winter and do it correctly or have a competent arborist perform the work. A judiciously raised up crown is nothing to be afraid of. BTW, I too doubt that this alone will do all that much to help the hedge. But that's not your goal. Your goal is to appear to be cooperative so as to prevent this fellow from exercising his legal right to lop off branches at the point where they cross the imaginary line separating your properties, which when done usually leaves bad branch stubs in locations on the tree where proper wound closure won't happen. +oM

That's a beautiful picture, sdogwood. I think your problem is one that will be repeated a lot. People are cutting down a lot of trees in fear of hurricane damage, and I guess I don't blame them, but I sure don't want to part with mine. An arbor would be a good idea, and plant some smaller trees if you have room. I'm thinking a cost/benefit analysis would be a good idea; we've saved I have no idea how many hundreds of dollars on air conditioning because of trees we planted, and one formerly small live oak we left. I guess a smart thing to have done would have been to estimate the money we saved and put it in a savings account to pay damage! Better than the way some insurance companies seem to be paying off. And it seems to me that if global warming is a fact, and I believe it is, the more trees and other plants we plant the more possible it would be to keep it from tipping over to really terrifying potentials. So plant! (As if we needed an excuse!)

If you can drop the native restriction and provide water in summer one of your best bets would probably be Fargesia bamboos. These can be quite nice, grow in shade and won't take 20 years to size up. If instead the natives only restriction is set in concrete then about the only choice you have is Thuja plicata. Local shady woods with vegetation containing species such as those you have listed as being existing have no bushy, attractive native evergreen species of more than shrub height other than this conifer - it is the only kind that looks like it would lend itself to serious screening of views. Where salal is present evergreen huckle-berry may certainly also be possible - these two often grow together in the wild, on those occasions when the Vaccinium is present at all - but unless stimulated with liberal watering, this latter, like other heaths including the salal can be quite slow- and rather small-growing, prone to weevil attacks beneath overhanging trees and so on. And lack density in heavy shade, as do most trees and shrubs. Finally it is often the case that when people ask for quick 15 ft. tall plantings to block something next door they are thinking in terms of this screening being over near where the source of the unwanted view is, want therefore such height. But they may not in fact be using that part of the property most of those times when they are wanting there to be a visual barrier present. So that installing a source of relief near where they are looking from instead, well inside their property would be more efficient - and perhaps even immediately effective, if an architectural feature or modification is used.