My experience:
I have two obviously well pruned cherry trees surrounded by thorny vines (greenbriar?)... they have been left alone by deer and human alike. So, natural fences do work.
The other cherry trees (replaced several times) have been mowed down, shredded to bits (deer rubbings), yanked by middle school pranksters, etc.
To counter:
I'm hilling up the trees now (to mimic HOA style plantings)... even using the same brand mulch.
I engage the kids to let them be part of the fun.
I spray with deer repellant which seems to have short term effect.
I buy taller trees (big box) that are much better established (cheaper than replacing many smaller underdeveloped trees)
The ideas I like the most from this thread are:
1) Planting in thickets. That rings true for my apple/pear trees. They are separated by six feet from the nearest neighboring trunk and it appears to have helped.
2) Letting the trees grow tall. The deer seem to eat every leaf 5ft and below. I like short trees, so the neighborhood kids can pick fruit... but it just isn't going to happen with 27+ deer in the same neighborhood (I counted them one time herded together).
Something new:
One thing I hear works well (and is somewhat discrete) is a "Wireless Deer Fence". It actually has a lure that attracts deer. When they lick the electrical contacts on the WDF device, they get a shocking jolt and avoid the area for long time. Apparently they work well.
