NATURAL REGENERATION
There are several ways in which trees reproduce
themselves, which is called natural regeneration.
They drop seeds - a few of which germinate into
seedlings. If hardwoods are cut down when they are
relatively young, their stumps can sprout. Some
hardwoods, including aspen, sprout from their roots
after they are cut down. Some trees sprout from a buried
branch, but those species are not here.
The heavier nuts of oak, walnut, butternut, and hickory
fall directly to the ground near the parent tree; but
they may be moved (this is called dispersal)
by birds, mammals, and gravity. In fact, when blue jays
in Germany were tracked, it was discovered that each
bird moved about 4500 seeds ever year. Squirrels not
only consume the nuts but also bury them; fortunately,
they do not remember where they put them all.
The lightweight seeds of elm, ash, and basswood have so
little food in them, that wildlife eat them rather than
store them. In their case, the trees have to
depend on the wind to disperse their seed.
The forester uses natural regeneration by selecting an
area that has two characteristics:
(1) many seedlings and saplings of desirable species and
(2) a canopy layer of undesirable species.
By removing the undesirable larger trees, the canopy is
opened to let in the sunlight. Some of the young
saplings have struggled in the understory, starved for
sunlight for 40 years. By opening the canopy, these
saplings will begin to compete for the sunlight, growing
fast and tall. |