As day turns into night, trees change. They don’t sleep, but are
occupied by other tasks
awaiting the dawn.
In the dark, trees don’t catch our attention. Because we depend
so much on sight, the
night steals away our primary sense, and we feel uncomfortable.
Our other
long-distance sense seems to explode with sound.
The insects’ clicks, frogs’ croaks and the calls of birds and
humans’ pets all generate a
calliope of noise we associate with the night.
The rustle of breeze-blown leaves and squeak of rubbing branches
can barely be heard
above the din of the animals.
But the silence of the trees doesn’t denote a lack of activity.
Trees are performing four
major tasks at night: refilling with water; moving and using
daytime-made food;
shoring up cell walls and damage-boundary zones; and growing
roots.
During the day, roots can’t take up water fast enough to meet
the needs and losses the
leaves generate. The tree develops a water deficit during a hot,
sunny day.
By the end of the day, the leaf machinery closes down with a
water shortage still
present. Over the nighttime hours, a tree keeps drawing up water
to reduce this deficit.
Feeding the leaves and roots is critical to tree health. When
the leaves stop making
food as day ebbs, they start to demand food to keep them alive
through the night.
Carbon chains assembled within the leaf by photosynthesis during
the day have been
stored close at hand for the night. The rest of the food has
been shipped downward to
the stem and roots. The major internal highways in trees are
busy shipping large
amounts of growth materials and food throughout the tree.
The third major process trees do at night is sealing off cell-
wall components welded
together during the day.
This epoxy-like coating, called lignin, holds in position the
strong, fibrous cellulose
made during the daytime. The tree also prepares and deposits
defensive materials
around wound sites and infections.
Trees’ final major nighttime job is propelling roots through the
soil.
Root growth is vital for gathering and controlling resources.
Colonizing new soil areas
which have plenty of available resources for growth will assure
the tree’s survival.
Trees use water pressure to expand cells near the root tips. The
growing walls are
surrounded by strong fibers that only allow the cells to expand
in one direction —
forward.
Creatures of both day and night, trees are the elevated stage
and overhanging platform
on which night life is played out. They’re staging areas for new
pest conquests and
damage recovery zones. From the moment dew is pulled from the
air onto leaves until
the new sun dries the leaves, fungi seek openings and attack.
The nighttime smells of the forest are unmistakable. Breezes too
faint to feel carry the
wisp of pine, soil molds and damp wood. The smell of “green”
from the darkened
garden, orchard and forest can be as mentally soothing as the
daytime sight of the
woods.
The next time you follow the march of a tree’s moon shadow
across your yard, think of
the night trees. Help your trees and forests to be healthy, both
night and day.
