Cordon

"dear john, i,ve always been led to believe that plants and trees specifically do not have a predetermined amount of cell cycles and can be likened to a coral reef where the oldest living parts are only at most a few years old but rely on the structures of their ancestors for support."

It is true that with plants there is really only a small amount of tissue that is active and the rest is either inactive, or simply serving as structural material. however unlike a coral reef that living tissue is not the result of sexual reproduction. It is simply the result of cellular division. Eventually, as with all living things, this DNA transcription and replication will result in errors that will result in the eventual death of the organism.

Though I can't prove it, I think that eventually even if given optimal growth conditions, fertilization, and care a tree will die. This may take millenia but eventuall,y as with all living things, it will die.