How does a tree know what to do?

The trees stand all around me,
      straight and tall,
defying gravity,
        a forest against the odds.
They look upward,
   towering strong in their defiance,
living in a way
           they should not be able to thrive,
    but they do,
not balanced precariously,
             but deeply rooted,
       bearing fruit,
    and wearing the colors of the season
                  right on time
                         every year,
      like casting aside green shoes after Labor Day.
How do trees know what to do?
Just fulfilling their purpose,
           bringing hope to the world
                     and glory to God who made them.
But their brilliance every fall
       is only a practice
                for what is yet to come.
For when the world is restored,
         nature will also be turned rightside up,
and we will witness
that all along the trees have just been rehearsing
               the astonishing chorus of creation.

Then shall all the trees of the wood
                    sing for joy...

                                 Psalm 96.12