Aerial forest surveys track continued spread of spruce beetles across Colorado forests

State, federal scientists track forest health

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Aerial survey results show how spruce beetles are taking a toll across Colorado’s forests, with new areas of infestation in the Sange de Cristo, the West Elks and even the northern mountains.

Spruce beetle populations are surging in the southern Rocky Mountains. bberwyn photo.

Spruce beetles are still spreading in the southern Rocky Mountains. @bberwyn photo.

By Bob Berwyn

The latest results from aerial surveys of Colorado forests shows that spruce beetles are doing the most damage, with infestations detected on 409,000 acres across the state, expanding onto 182,000 acres of previously unaffected forests. Since 1996, spruce beetle outbreaks have caused varying degrees of tree mortality on more than 1.5 million acres in Colorado.

The mapping shows spruce beetles spreading outward from the San Juans to the West Elk Mountains, the Sangre de Cristo Mountains and into the northern part of the state around Rocky Mountain National Park. See the full report here: http://www.fs.usda.gov/goto/USFSR2ForestHealth.

State forest experts said it was the fourth year in a row that spruce beetle outbreaks caused widespread tree mortality. As populations of spruce beetles expand, they are starting to affect higher-elevation stands of Engelmann spruce. The report says blowdown events, combined with long-term drought stress, warmer temperatures and extensive amounts of older, dense spruce, have all contributed to the ongoing spruce beetle outbreak. Continue reading

Study says some forests may not recover from mega-disturbances in the global warming era

Colorado aspens

There have been significant die-backs in Colorado aspen forests during recent hot droughts and the stands may never regenerate in some areas because of global warming. @bberwyn photo.

Giant fires, insect outbreaks could be ‘game-changer’ for some forests

Staff Report

FRISCO —Forest Service researchers say “mega-disturbances” like giant wildfires and insect outbreaks are likely to hasten the slow demise of temperate forest ecosystems in the coming decades.

Even without those large-scale events, some forests appear to be transitioning to shrublands and steppe, and big disturbances could speed that process, according to a new study published this month in Science. Continue reading

Study: Western pine beetle outbreak may have weakened next generation of trees by wiping out key fungi

Hawk's wing Colorado mushrooms

Important mushroom species that help trees grow were wiped out by the mountain pine beetle epidemic, potentially leaving future forests more susceptible to renewed insect attacks. @bberwyn photo.

Widespread mushroom die-off dramatically lowers seedling survival rate

Staff Report

FRISCO — The recent pine beetle outbreak in western forests may have left the next generation of trees more vulnerable to future pests, Canadian researchers concluded in a new study that examined how the wave of tree deaths affected fungi that grow together with lodgepole pines.

Many trees, including lodgepoles, are partly dependent on certain fungi that enable a nutrient exchange at the cellular level. But the pine beetle outbreak was so widespread that many of the beneficial fungi disappeared. Continue reading

Warming temps not the only factor in beetle outbreaks

Study shows regional variations in forest health equation

Annual aerial survey enable resource managers to map the spread of tree-killing bugs.

Annual aerial survey enable resource managers to map the spread of tree-killing bugs.

Staff Report

FRISCO — Warming winters across the western U.S. have had a nuanced effect on the severity of mountain pine beetle outbreaks, researchers said last week.

The absence of lengthy bug-killing cold snaps in some areas has helped fuel the growth of insect populations,, but milder winters can’t be blamed for the full extent of recent outbreaks in the region, according to a study by Dartmouth College and U.S. Forest Service. Continue reading

One more time: Beetle-killed forests are NOT more likely to burn, according to new CU-Boulder study

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Beetle-killed lodgepole pines in Colorado. bberwyn photo.

New CU-Boulder study has implications for forest managers and Red Zone communities

Staff Report

*More Summit Voice stories on beetle-kill and forests here.

FRISCO — Communities and resource managers looking to address the threat of wildfires should focus less on tree-killing beetles and more on the underlying forces driving the trend toward larger fires.

Warmer temperatures and increased drought are the key factors, said Colorado-based researchers who took a close look at patterns of beetle-kill and wildfires in recent years.

Their study found that western forests killed by mountain pine beetles are no more at risk to burn than healthy forests. Those findings  fly in the face of both public perception and policy, the scientists acknowledged.

“What we are seeing in this study is that at broad scales, fire does not necessarily follow mountain pine beetles,” said CU-Boulder Research Scientist Tania Schoennagel, of the Institute of Arctic and Alpine Research. “It’s well known, however, that fire does follow drought.” Continue reading

Aerial survey shows pine beetles waning, but spruce beetles continue to spread across Colorado forests

Aerial surveys help track forest changes over time

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Nearly every mature spruce has been killed by spruce beetle in this drainage on the Rio Grande National Forest.Photo: Brian Howell.

Spruce beetles are spreading quickly in southwestern Colorado.

Spruce beetles are spreading quickly in southwestern Colorado. Graph courtesy USFS.

By Bob Berwyn

FRISCO — There’s good news and bad news from Colorado’s forests. Mountain pine beetle activity has faded to the lowest level since 1996, but spruce beetles continue to spread in the San Juans and in northwestern Colorado.

The spruce beetle outbreak was detected on 485,000 acres in 2014, compared to 398,000 acres across the state in 2013, according to the U.S. Forest Service and the Colorado State Forest Service. The annual aerial survey by the two agencies shows that the spruce beetle outbreak expanded to 253,000 new acres. Continue reading

Study: Small trees key to long-term forest survival

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Forest treatments that focus on removing smaller trees may not be the best tool for western dry forests, according to new research by University of Wyoming scientists.

Study shows many treatments in western dry forests are misguided

By Bob Berwyn

FRISCO — Mid-elevation forests in the western U.S. have survived centuries of drought, wildfires and insect onslaughts by hedging their bets with a diversity of tree sizes, Wyoming researchers said after studying forest plots from the Pacific Northwest down to Arizona and New Mexico.

The research showed that the biggest threat to those forests is from insects and not wildfires. Historically abundant small trees enable those forests to rebound after tree-killing bugs move through. Continue reading

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