I know that most of the woody cells in most species of
mature trees have lost their cytoplasm and function only
as physical support, transport, or protective cells. They
are no longer alive in that they no longer have any
metabolic activity. This is true for mature cork as well.

I'm curious to know the percentage of cells in a tree
that are still alive. Or alternatively, what percentage of
a mature tree's mass is composed of living tissue?
I would think that the meristematic tissue, leaves, and
living supportive tissue is a relatively small percentage.

I look out my window at the huge stately trees in my
back yard and I'm curious to know how much of what I
see is alive and how much is scaffolding, pipes and
covering built up over the years by a relatively small
bit of living tissue.

Does anyone know the answer? Educated guesses
and speculations are also welcome (this is, after all, the
Internet

Thanks.

Alan