Is there any known about viability of all these planted trees? What percentage of them "make it"? Anecdotally, I've seen a good portion of trees planted near o

Is there any known about viability of all these planted trees? What percentage of them "make it"? Anecdotally, I've seen a good portion of trees planted near other wooded areas not make it for one reason or another. I think the planters had already lost trees in the past to deer, because they had plastic guards around the stalks. However, many only lived for a couple of years and dried up. It makes me sad to think about it.