Jan. 25,
2013 — Population explosions of pine beetles, which have been decimating
North American forests in recent decades, may be prevented by boosting
competitor and predator beetle populations, a Dartmouth study suggests.
Bark beetles
are the most destructive forest pests worldwide. Management and climate change
have resulted in younger, denser forests that are even more susceptible to
attack. Though intensively studied for decades, until now an understanding of
bark beetle population dynamics -- extreme ups and downs -- has remained
elusive.
The
Dartmouth-led study, published in the January issue of the journal Population Ecology, confirmed, for the
first time, that the abundance of a certain animal species -- in this case the
southern pine beetle -- fluctuates innately between extremes, with no middle
ground.
"That is
different from most species, such as deer, warblers and swallowtail
butterflies, whose populations tend to be regular around some average abundance
based on food, weather, and other external factors," says Matt Ayres, a
professor in the Department of Biological Sciences at Dartmouth and senior
author on the paper. "They don't appear and disappear in cycles. Rather,
they exist in two stable equilibrium states -- one of high abundance and the
other of scarcity." Once the population pendulum swings toward the high
end, it won't quickly or easily swing back.
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