White Pine
Pinus strobus
When white pine forests bloom in
spring, you can sometimes see spectacular columns of pollen rising
up through the trees like smoke. Luckily, the pollen doesn't cause
allergies in most people. Pine pollen is lightweight and shaped
like a pair of wings. It can travel great distances, fertilizing
trees far away. This is how vast pine forests once spread across
the eastern United States and Canada. Some say that before European
settlers arrived on the continent, a squirrel could travel its whole
life in the trees without ever touching the ground. The early settlers
saw these towering pines as valuable timber. Scientists estimate
that the forests contained enough boards to wrap around the planet
millions of times. By the late 1700s the forests had been cut down
for ship masts, bridges, homes, and furniture. In the early 1900s,
U.S. foresters began a program--called reforestation--to plant large
numbers of young trees to renew the forests. White pines grow fast,
and today they once again cover large areas of the Northeast. Without
disturbance from humans, these towering trees can keep growing for
hundreds of years. But once again they are threatened, this time
by acid rain caused by urban pollution.
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