Even trees die

I stepped in dark and saw that I had found
A hoary oak tree, warring with the sky,
Then caught a root and fell through lashing limb
To scar my hands upon the rocky ground,
And feel that I would never leave the gloom.

Upon its trunk, the scars of smoke and fight.
A summer sun was blocked by its green crown
Because it felt the ground could do without
The sun at day, or starry sky at night.
This patch of hill, at least, it could consume.

In sickness leaking sap from gnarled trunk
Not felled from high, but rotted all around.
No useful wood did I expect to find
Inside its heart - all black, withered, and shrunk.
The evil is that shadow hides our doom.

The forest silent, watching when it fell
And fire turned its rotting wood to ash.
Where it once stood the yellow sun beats down,
And burnt or not my skin can hardly tell.
The undergrowth now overgrows its tomb.

What I called shadow, others knew as shade,
While from my heels a thin shadow is seen.
If I held up my arms could I become
The dark longevity that nature made?
Trees die, and when one dies it just leaves room.