Are trees immortal?

Factual Questions
1

By that I mean: I know trees can live for a very long time, but will they live forever if not killed by changing climate conditions/ changing soil conditions/ lumberjacks/ beavers/ insects/ lightning strikes/ forest fires/ diseases/ etc.?

That is to say, do trees eventually die due to something akin to old age? For that matter, do trees show any signs of aging, other than getting bigger? I mean, I understand that the human body changes on the cellular level as we age – does something similar happen with trees? If not, do any plants age? Or is it just that some can survive the cold of winter and some can’t?

And if trees don’t age, why not? I mean, I thought aging in humans had something to do with DNA strands getting slightly shorter with each replication. (But I’m not at all sure I have that right.) If so, why doesn’t this happen to trees?

2

I don’t know about old age in the genetic sense, though I would assume that would be the case, I’m fairly sure that the tree would eventually exceed the ability of it’s constituent materials to support it’s weight. This could take a very long time, depending on the tree, of course.

3

Cecil Adams on Do trees die of old age?

4

Trees do get diseases. I figure that there must be some diseases that hinder the life span of trees. So I’m WAG ging a No on this one.