ARE TREES AND LIMBS BECOMING MORE BRITTLE?

This major limb of a sugar maple (Acer saccharum), shattered when the tree was felled onto a cushion of over one foot of snow. The tree appeared healthy and had not received damage to its major limbs in the ice storm of January 1998. The limb was on the top side of the tree when it fell and thus was not subject to any crushing, direct impact or bending, yet it shattered for more than 15 feet along the limb. Please see the glove in the center of the photo as an indicator of size. Photo by Gerry Hawkes - March 7, 1998

As white pines (Pinus strobus) become less healthy, their limbs become brittle and break more easily during storms. The brittle wood in the limbs is often more red than the normally "white" wood of healthy limbs. The red color of the wood in a brittle limb can be seen in the photo of a broken branch end on the right. The problem of brittle limbs in white pines is apparently becoming widespread regionally. Photo by Gerry Hawkes - March 24, 2001

Since the early 1990's I have observed that limbs seemed to be breaking more easily than they had in earlier years. I have received reports from buyers of veneer logs that mills have observed wood becoming more brittle or "brash".

In December 1996, central New England experienced its most costly and prolonged power outages of any previously recorded when a heavy snow storm caused an inordinate number of limbs to snap and trees to uproot. As bad as that was, it was dwarfed by the tree damage and power outages that occurred from the massive January 1998 ice storm that smashed millions of acres of trees in Vermont, New Hampshire, Maine, New Brunswick, Quebec, Ontario and New York. The build-up of ice was extremely heavy in many places in the January 1998 storm, but the snapping and uprooting of trees exceeded what might be expected.

We must look at the role of air pollution in the increasing frequency and degree of damage to our trees and forests. Is global climate change leading to more severe and unusual weather events? Is acid rain impeding the uptake of calcium and other nutrients by trees thus weakening the wood?

- Gerry Hawkes

For a research report that supports these observations please see

Wood as a Bioindicator of Air Pollution Impact on Forest Ecosystems
by
Stanzl-Tschegg, Stefanie, Hinterstoisser, Barbara, Halbwachs, Gottfried, Grabner, Michael, Hofer, Silvia, Hofinger, Andreas, Mengl, Michael, Wagenführ, Rudi, Wallner, Gabriele, Wimmer, Rupert

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Contact Gerry Hawkes: ghawkes@eco-systems.org