Deer don't eat redwood willingly, there is too much other vegetation that they greatly prefer (such as ceanothus).
I didn't know that, but my comment was more generic. For example, beaver will cut down a lot of shoots. I was just speculating that there are natural thinning processes that can be "mimicked" in an ecosystem that is not entirely natural. (Out here in the East, the deer overpopulation problem has entirely removed much of the forest understory, with detrimental effects for songbird populations. A recent report also indicated that acid rain might affect soil chemistry and detritus, which also affects brush and the availability of calcium, which ALSO is detrimental to songbirds, and the acid rain problem is much worse in the East.)