I suspect the forester Bob is referring to was not likely speaking in such absolutes. If it was George Zimmerman, I'm sure that wasn't the case. As we all know, deer are a natural part of our local environment, but so were the large predators that once controlled their population. Add to lack of natural predatation the adaptability of deer to living in close proximity to humans, similar to Canada Geese, gulls and raccoons and you have a population way out of balance. Besides cedar, they've over-browsed native understory plants in countless suburban woodlots, often allowing invasive alien species to move in and take their place. I had six deer in my back yard just last night, which is the first such occurrence in the 35 years I've lived here. My hostas and any other plant they like are eaten to the ground, also a new experience here.
But going back to the deer enclosures, I've was shown two experimental plots some years ago, where effects of fencing on cedars were studied. Both were old clearcuts where cedar was returning poorly. A portion of the plot was surrounded by a solar-powered electric fence. The height didn't keep motivated deer from getting over but greatly reduced the number that did. At the time I visited the sites the young cedar inside the fence was growing as thick as a cornfield, while the trees outside the fence were primarily maple, gum, and a scattering of magnolia. The contrast was striking. So, yes, they do work. It's simply not an implication that cedar will not grow anywhere without the fencing. There are two many variables as you go from site to site to say that.
