Pointing the way to pine beetle control, but at what cost?

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Pine beetle-killed trees in Summit County, Colorado.

Dartmouth scientists study pine beetle population dynamics

By Summit Voice

SUMMIT COUNTY — Dartmouth scientists say they may have found a pathway to keeping pine beetles in check, showing that their populations fluctuate 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,” said 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, Ayres explained.

According to the new study, forest managers might be able to keep pine beetle populations at the low end of the scale by boosting competitor and predator beetle populations — but they don’t address how that could affect the overall equilibrium of forest ecosystems, especially those where older trees need a change agent like bark beetles to spur regeneration. Continue reading

Study: Forest disturbance key to diversity

Forest disturbances help boost diversity.

Natural patterns of disturbance and regrowth can guide land use practices

By Summit Voice

As much as we picture a “perfect forest’ in our mind’s eye, the reality is that forests are dynamic ecosystems, subject to windstorms, avalanches, insect invasions and wildfires. And while the widespread perception is that these so-called disasters are a blight on forests, they are, in fact, crucial drivers of diversity and renewal.

 

Washington State University scientist Mark Swanson recently studied forest areas hit by major disturbances, including the 1980 Mt. St. Helens eruption and suggested that land managers can alter practices to mimic disturbances an enhance diversity, creating areas with a wide variety of species, including rare and endangered plants and animals.

“The 1980 eruption of Mt. St. Helens … created very diverse post-eruption conditions, and has some of the highest plant and animal diversity in the western Cascades range,” said Swanson, an assistant professor of landscape ecology and silviculture in Washington State University’s School of the Environment. Continue reading

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