Ostensibly related to nature, but not really. Let' say instead impermanence and its contrary. Another poem, this one from Rosanna Warren.
MAN IN STREAM
You stand in the brook, mud smearing
your forearms, a bloodied mosquito on your brow,
your yellow T-shirt dampened to your chest
as the current flees between your legs,
amber, verdigris, unravelling
today's story, last night's travail ...
You stare at the father beaver, eye to eye,
but he outstares you-you who trespass in his world,
who have, however unwilling, yanked out his fort,
stick by tooth-gnarled, mud-clabbered stick,
though you whistle vespers to the wood thrush
and trace flame-flicker in the grain of yellow birch.
Death outpaces us. Upended roots
of fallen trees still cling to moss-furred granite.
Lichen smolders on wood rot, fungus trails in wisps.
I wanted a day with cracks, to let the godlight in.
The forest is always a nocturne, but it gleams,
the birch tree tosses its change from palm to palm,
and we who unmake ourselves unmade
if we know, if only we know
how to give ourselves in this untendered light.
Rosanna Warren, 2006
Incidentally, here is another one by Warren, "Lake," over at Slate.