Tuesday, November 17, 2009

Tree quiz #2

In a forest in Northboro, there were many 1-2 ft diameter white pines
scattered among a variety of much younger deciduous trees. Almost every
large white pine had a forked trunks about 6-15 feet off the ground, as
shown above. What caused this? What does it tell you about the growing
conditions of these pines at the time the tree was affected?

(I'll admit I am not entirely sure I have the right answer. Maybe one
of you will know more about this.)


  1. Yay, more Community Ecology! These are white pines that were hit by the white pine weevil, which lays its eggs in the terminal shoot and kills it. The weevil only lays its eggs in trees that are under 40 ft. high and have plenty of sunlight. The tree responds by branching; if it is by itself in a field it may branch several times. But it seems like most of the time there are enough other trees around it that they just fork once and then continue their race to the top of the canopy.

  2. That was exactly my thought. Thanks for confirming.

    So now I have a question: If it can sprout when damaged 6 ft off the ground below any branching, why can't it stump sprout when cut almost to the ground, the way deciduous trees do?

  3. Never mind my question. It was stupid. Obviously, if the weevil attacks only the leader, there were branches below it when the tree was young. But they've since fallen off.