Northern Woodlands / Winter 2016 47
n the middle of a frozen New Hampshire
night in January 2015, Geoff Schwaner was
in Hubbard Brook Experimental Forest,
standing on the back of a UTV and spraying
water 100 feet up into the air with a fire hose.
The water came back down in a fine, frozen
mist, attaching itself to trees at the instant
of contact and coating them thickly with ice. At
first, the branches clinked together ethereally,
then, as more and more ice accumulated, they
bent, snapped, and loudly broke, crashing to the
forest floor below. Some trees were wrenched
from the frozen ground entirely, their root systems unable to support the added weight.
Schwaner is the field coordinator for an elaborate experiment designed to study the effects of
ice storms, awesomely destructive yet strangely beautiful weather events with which most
Northeasterners are all too familiar. The storms
are caused by clouds of damp, warmer air moving over a ground layer of frozen air: as rain
droplets fall from the warmer layer into the colder one, they supercool – that is, they dip below
their freezing point without crystallizing – but
do not freeze until they make contact with a solid
object, like a tree branch. Once that freezing process begins, however, new water molecules bond
rapidly with the growing encasements of ice, and
entire sections of forest can be thickly and dangerously glazed in not much time at all.
In North America, ice storms typically wreak
havoc in a belt stretching from Texas to southern
New England, but climate-change science suggests that as the planet warms, the particular
atmospheric conditions necessary for the deadly
storms will become more common across a
broader and more northerly geographic range.
What’s even more alarming is how little we still
know about the ecological impact of ice events.
“No long-term ecological study of ice storms has
ever been conducted,” said Lindsey Rustad, one
of the experiment’s investigators. “We know from
the literature that they are very likely to become
more frequent and more severe, and yet there is
hardly any quantified record of their effects on
the edge of a northern hardwood forest.”
WANT A SNEAK PEAK
By Ben Cosgrove
An “ice storm” comes to Hubbard Brook Experimental Forest.