aerial survey of the damage, as did other neighboring states. Schaberg, along with his colleague at the University of Vermont, Gary Hawley, hastily lined up a master’s student to
head out and quantify the amount of damage up close.
Brynne Lazarus visited 28 different sites around the region and came back with dramatic findings: 90 percent of all red spruces she looked at had incurred damage that winter. On average, trees lost nearly half of their new foliage and a third of their new buds.
The damage was particularly bad on older, dominant trees at higher elevations, where the
trees were more exposed.
Schaberg and his colleagues wondered what long-lasting effects such severe damage
would have on the trees. They knew that repeated injury had weakened the trees’ immune
systems and slowed their growth, contributing to the chronic decline, but how would this
affect the trees’ carbon storage?
In 2010, Hawley and Schaberg assembled another team, this time led by graduate
student Alexandra Kosiba, to measure just how much carbon sequestration had been
lost by that massive winter injury event back in 2003. Kosiba took cores from nearly 400
red spruce trees around the region and examined their growth rings. What the team
found along the way was in some ways more interesting than what they had originally
set out to do.
“We did learn that there was at least a three-year reduction in growth following the
harsh winter of ’03,” Schaberg told me, “and that it equated to almost 2. 5 million tons
of sacrificed CO2 sequestration…but what really stole the headlines was the upsurge in
growth that the trees have been experiencing since then – they’re growing like crazy!” he
The data show that the trees were growing at nearly twice the rate of the average red
spruce recorded over the past century.
Searching for answers
Have air quality regulations succeeded in squelching the effects of acid rain? Is climate
change mitigating winter injury to the spruces? Are these long-lived trees just now hitting
their prime? Is the same thing happening elsewhere in the natural range of red spruce, or
just in New England? “Well,” Schaberg says, “that’s what we’re trying to figure out.”
As a scientist, he is hesitant to extrapolate beyond what the data are capable of telling
us. As it turns out, the problems that plagued red spruce for so long are more complicated
than they appeared.
“Through our annual monitoring programs, we’ve learned that there really needs to be
a trifecta of conditions for the winter damage to occur,” Schaberg explained, after I asked
him whether the brutal winter of 2014-2015 in the Northeast resulted in another major
injury event. “First, there’s the acid rain issue as a prerequisite, having leached the calcium
from soils and needles; second, the trees must be predisposed to stress by poor growing
conditions in the previous year(s) – drought, excessive heat, a late frost…things that further set the stage, so to speak. And then, throw in a very harsh winter – and that’s when
we really see the damage show up.” In other words, it needs to be a perfect storm.
Researchers in New England are now trying to tease apart the confounding variables
that influence tree growth in order to find out what’s really behind the recent boom.
Kosiba and others are taking a closer look at various weather- and climate-related metrics
– particularly warmer winters and extended growing seasons – to see which, if any, correlate to the growth rates.
Others are taking advantage of new capabilities afforded by geographic information
system (GIS) models and better data to estimate the acid pollution loading across the
region and to compare it to the growth rates of specific trees.
Elsewhere, Schaberg says, researchers are undertaking studies to determine if other
tree species that fill a similar niche – temperate conifers such as white pine and hemlock –
are also growing better as of late. Perhaps whatever is driving red spruce is affecting other
trees, as well.
“Through our annual
we’ve learned that there
really needs to be a
trifecta of conditions
for the winter damage