Chemistry of Plants:
Photosynthesis: CO2 + H 2O
+ Energy -- chlorophyll --> sugar + O 2
during photosynthesis , trees and other plants use carbon
dioxide (CO2) from the air, water (H2O) from the soil, and
energy from the sun. Using chlorophyll in leaves as an
"assembly jig," their main product is sugar. Oxygen (O2 )
is released into the air as a by-product -- which is very
fortunate for people and other animals.
is the opposite process, reversing the arrow in the
equation. The energy stored in sugar is released for
growth and other life processes. The plant "burns" sugar,
combining it with oxygen to release energy.
Respiration: CO2 + H2O + Energy <------------ sugar + O2
hydrogen, and oxygen are rearranged into materials that
cellulose for wood and the tissues of bark, leaves,
flowers and fruit, etc.
growth regulators that coordinate the plant's activities
natural fungicides with which the plant protects itself
starch, for energy storage in a form that can be
converted back into sugar,
redissolved, and moved for use in another location
Sugar, the tree's basic building material, is easily
dissolved in water and
piped away from the leaves for use or storage.
The sugar may:
become the chemical building blocks for wood, leaves,
flowers, seeds, growth
converted into starch by enzymes in living wood cells
formed during the
past few years. There the starch is "parked" where it
can easily be converted
back into sugar and moved again to where it is needed
for new spring growth,
the natural fungicides that trees make to fight decay
after an injury.
It is hard
to overestimate the importance of plant vigor. All plants
live by using the energy they have captured and stored in
sugar. Everything in a plant is built from raw materials
gathered from soil and air; and all of its life processes
-- growth, uptake and transport of water and minerals,
reproduction, defense against decay -- require energy from
with respiration in animals and combustion in gasoline
engines, carbon dioxide and water are released as
AGING IN TREES
aging means that the individual loses its ability to
replace damaged tissues. But as a tree ages, it loses its
ability to feed and protect the tissues where it stores
energy; the tree sheds the parts that are most vulnerable.
Shigo differentiates between trees' dynamic and static
mass. The dynamic mass of a tree is the sum of all the
parts that are alive and participating in the capturing
(photosynthesis) or storage of energy. The static mass is
the remainder of the tree, which does not "pay its own
way" and must be protected.
between dynamic and static mass constantly shifts,
starting out with little or no static mass in a tree's
youth, and ending up with very little else. Not only the
leaves, but also the bark of a seedling contain
chlorophyll, and take part in converting the energy of
sunlight into sugar. Practically all the wood cells in the
young stem and twigs are alive, so they contain starch
granules when extra energy is available. Starch is the
only product made from sugar that can be converted back
into sugar, to be transported and used.
As a tree
ages, the outer bark and the earliest wood cells (covered
over by more recent layers) lose their vitality and die,
becoming part of the tree's growing "static mass." As long
as the dynamic mass can protect it from injury and decay,
no-living wood serves as the tree's flexible skeleton. But
as the tree ages, it loses its ability to protect all of
its "static mass." Like dead leaves, dead twigs are easily
shed; and often the tree is able to keep decay out of its
trunk and large branches by shedding smaller branches that
have died. But eventually every tree reaches a point where
its rent is more than its income, and the tree dies.
All this is
connected closely to how trees defends themselves against
injury and decay, and how we should manage trees for
maximum beauty and safety.