In Adam Warren's thread, he indicates his club will replace the trees that will be cut-down with new trees "to protect par". Generally speaking, I'm not a fan of trees, especially ones that aren't native to the land developed into a golf course, however in many cases I do think they are likely needed at some level for strategy. I'm interested in peoples thoughts of other ways to reward good shots and penalize poor shots (on existing courses, without the ability to build new greens, etc) without trees.
I have attached a photo of the "newer" 9 holes at our club, which was integrated into an existing 9 on the other side of the clubhouse in the mid 80's (pictured holes are par 36, 3,400 yards). The original holes were built in 1904 on better terrain and have a fair amount of mature oaks. I understand how the Club got to where it is with trees on the new 9. When it was first built, a hole like #2 offered no penalty for missing left, and probably a better angle. In response, more and more trees were added, without realizing how big they would get in 25 years. We do have some "native areas" and we are discussing expanding many, but they are really penal because grow in a manner that lost ball is likely, so simply expanding native areas between all fairways isn't really a viable solution. Certainly having 25 trees in area where 10 would be suffice (left on 2, left on 14) probably has zero impact on "protecting par" but significant impact on maintenance.
One option would be to grow the rough higher and keep greens a little firmer to put a premium on hitting the fairway to stop the ball. The issue with that approach for us is bluegrass fairways aren't really conducive to light lies to spin the ball, or firm run-up areas. I love seeing the many courses profiled here, like Oakland Hills, where many holes have only a couple trees, however the combination of length coupled with difficult greens do penalize off-line drives, however for shorter clubs, with less demanding greens, I'm not sure that is a viable solution. I have played seemingly dozens of courses that are between 6,000 - 6,800 yards that when faced with this issue, all did the same thing, planted too many trees (often many more trees than our club did), so I know we're not alone, but I'm curious for others thoughts on the issues of penalizing off-line drives, but not overloading with trees.