On Wed, Oct 28, 2015 at 10:11:35AM -0700, Phil Pugliese (via tml list) wrote:
> So, how long of a blackout is required to start killing plant life?

If the plant life is native to a planet that regularly (even if
infrequently) goes into total shadow for a week or two, then it's
quite likely that the plant life has adapted to that.  If the planet
normally has seasons, it's not likely to be much worse than an
especially bad winter.

If we're talking about a long blackout on a planet where the plants
don't normally see any such thing, it's going to be pretty bad even
after the first week.  The temperatures will drop pretty quickly,
possibly more than 10 K per day (something like 20 F).  A
near-waterworld like Earth would drop more slowly until the oceans
freeze over, but thereafter the rate would match that of drier worlds.

> How long does if have to be for big trees to be affected to the
> point that they could fall down (even if it doesn't happen till
> later)?

Dead trees (at least the Earth kind) usually don't fall down for a
very long time after they're dead - up to centuries depending on
species.  Much of the interior of a trunk is already dead even in
living trees, but continues to provide structural support for the life
of the tree and beyond.  After the tree dies it is more likely that
the interior will start to decay, but that can take a very long time.

- Tim