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

Study: Pine beetle outbreaks not a big factor in the ecological severity of Western wildfires

Dead and dying lodgepole pines in Frisco, Colorado.

Dead and dying lodgepole pines in Frisco, Colorado.

Study shows no clear link between beetle-kill and ecological severity of western wildfires

Staff Report

FRISCO — For all their frenzied tree-killing during the past 10 years, mountain pine beetles haven’t been a big factor in the ecological severity of wildfires in the West, a team of university scientists said this week.

Weather and topography are the main factors in determining how much damage a wildfire does to forest ecosystems, according to the researchers with the University of Wisconsin-Madison and the Washington State Department of Natural Resources.

The new study, published in the Proceedings of the National Academy of Sciences, provides some of the first rigorous field data to test whether fires that burn in areas impacted by mountain pine beetles are more ecologically severe than in those not attacked by the native bug. The study didn’t look at fire behavior, including how fast they spread or how dangerous they are to fight. Continue reading

Are New Mexico forests holding steady in the face of climate change, drought and wildfires?

New inventory assesses state’s woodland resources
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STAFF REPORT

FRISCO — Mortality is increasing and growth is slowing down in New Mexico’s forest lands, according to a new forest inventory released in late August. The only species showing overall growth are ponderosa and piñon pines, as well as junipers, as insects, wildfires drought and disease take an increasing toll on the state’s woodlands.

Forests grow on about 25 million acres in New Mexico, with 44 percent on private lands and 31 percent on national forest lands. About 40 percent (10.8 million acres) of the forests are piñon-juniper woodlands, by far the state’s most extensive forest type. Gambel oak is the most abundant tree species by number of trees, and ponderosa pine is the most abundant by volume or biomass. Overall, researchers estimate there are more than 6 billion live trees growing in the state.

The inventory documented the drought-induced piñon pine die-off in the early 2000s, estimating that about 8 percent the species died, but noted that the mortality rate has tapered off.New Mexico’s aspen forests, covering about 380,000 acres, held steady in the past decade. Continue reading

Is out-of-state firewood a threat to Colorado trees?

Trees? Or toothpicks?

Beetle-killed trees near Frisco, Colorado.

State Forest Service warns against transporting firewood

Staff Report

FRISCO — It may be a little like the Dutch boy putting his finger in the leaky dike, but Colorado Forest Service officials are warning that transporting firewood from place to place may increase the spread of invasive tree-killing bugs.

Moving firewood even short distances increases the risk to Colorado’s native forests and urban trees. With the 2013 detection of the highly destructive emerald ash borer in the City of Boulder, and ongoing bark beetle epidemics in the state’s mountain forests, the Colorado State Forest Service wants to be sure people are aware of the risks associated with moving firewood. Continue reading

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