"FTR, many tree species can live for hundreds of thousands of years."
The oldest known tree in the world is 5000 years old.
No individual trees are known to live hundreds of thousands of years.
There are clonal trees, like aspens, that could live as a colony for hundreds of thousands of years, but that's not quite the same thing (and our oldest verified example is only 80k years old).
Ok, you're right that it depends on what you count as a tree. An aspen "colony" is a living organism, and its "trees" visible aboveground are merely its stems. Such organisms may live as long as 1,000,000 years.
