Climate
change creates complicated consequences for North America's
forests - in some cases permitting insect outbreaks, plant
diseases, wildfires and other problems
by Staff Writers
Hanover NH (SPX) Oct 18, 2013
Dartmouth professor Matt Ayres studies the southern
pine bark beetle, a forest pest that may be the largest source
of disturbance in coniferous forests throughout North America.
Credit: Eli Burakian.
Climate change affects forests across North America - in
some cases permitting insect outbreaks, plant diseases,
wildfires and other problems -- but Dartmouth researchers say
warmer temperatures are also making many forests grow faster and
some less susceptible to pests, which could boost forest health
and acreage, timber harvests, carbon storage, water recycling
and other forest benefits in some areas.
The Dartmouth-led study, which appears in the journal
Ecological Monographs, reviewed nearly 500 scientific papers
dating to the 1950s, making it the most comprehensive review to
date of climate change's diverse consequences for forests across
the United States, Canada and the rest of North America.
Tree-killing insects and plant diseases are natural
elements of healthy forest ecosystems, but climate change is
rapidly altering the distribution and magnitude of forest
pestilence and altering biodiversity and the ecosystem. For
example, pine bark beetles have recently killed trees over more
area of U.S. forests than wildfires, including in areas with
little previous experience managing aggressive pests.
"One of our prominent challenges is to adapt forest
management tactics and generalize the underlying theory to cope
with unprecedented changes in pest pressure," the authors say.
Results show that over the last 50 years, the average
global air temperature has increased about 1 F, while the
coldest winter night averages about 7 F warmer. That has
permitted population explosions of tree-killing bark beetles in
forests that were previously shielded by winter cold and made it
easier for invasive species to become established.
But tree growth rates in many regions are increasing due to
atmospheric change, which may increase resilience to pests.
Also, pest populations in some regions may decline, allowing
those forests and their environmental and economic benefits to
expand.