Summit County: Pine beetle numbers drop sharply

Only a few pockets of high activity remain 

Large swaths of Summit County forests survived the latest pine beetle epidemic. PHOTO BY BOB BERWYN.

SUMMIT COUNTY — The mountain pine beetle epidemic that spread through Colorado’s north-central mountains and other parts of the West is subsiding in Summit and Eagle counties, according to the Colorado State Forest Service.

A Colorado State Forest Service map shows the distribution of lodgepole pines in Colorado.

In the end, the bugs killed about 75 percent of the mature, susceptible lodgepole pine trees in the area, according to Colorado state forester Paul Cada. In neighboring Grand County, where lodgepole forests were even more prevalent than in Summit County, between 95 to 98 percent of the trees were killed by the beetles, Cada said.

He estimated that about 60 percent of Summit County’s forest cover consisted of lodgepole pine before the beetle outbreak, with 40 percent a mix of spruce and fir (along with a sprinkling of aspen and tiny pockets of trees like Douglas fir, which grow on rocky outcrops around Swan Mountain).

Doing the math, it looks like a little more than half of Summit County’s forests survived the explosion of insects more or less unscathed, but since lodgepole was such a dominant species, the infestation has changed the landscape for decades to come.

In Summit County, populations of the insects are dropping quickly back down to background endemic levels, said Cada, who’s been working with private property owners and local officials the last few years to mitigate beetle-kill impacts like potential fire danger.

Cada explained that, in between widespread beetle outbreaks — which are a normal part of lodgepole forest ecology — it’s normal to still have small pockets of infestations here and there.

“If we’re on a Bell Curve, then we’re on the downslope,” Cada said, adding that there are still a few active pockets where the pine beetles may continue to spread, including the Crown area, near Blue River and the Tenmile Canyon area. “The populations are really starting to decline,” he added.

For the most part, the bugs have simply eaten themselves out of house and home, he said. More moisture the past few years may have strengthened some of the remaining trees enough that they were able to repel the bugs on their own. And finally, as the insects moved south and west, they encountered areas of mixed forest, where it wasn’t as easy for them to spread.

Outside the areas where there are still active populations, Cada said property owners might be able to stop spraying trees with pesticides, or perhaps limit spraying to individual high-value trees.

“If I lived there, I probably wouldn’t be spraying,” he said, adding that he wouldn’t formally recommend against spraying, saying because it’s up to individual property owners to make that decision.

Read this story in the Vail Business Journal to see what’s happening with the pine beetle in Eagle County.

 

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4 Responses

  1. Seemingly good news. Lessons learned? Natures way of doing business, perhaps not just about the trees, but foretelling beyond, Re: the climate change[s] we are facing, how things get out of balance, like when the return spring on your carburetor breaks and it sticks open, with no control.

  2. Lesson learned? Diversity seems to be key.

    • Yes, but we can only do so much to diversify the forest. In some places, the forest will always be dominated by lodgepole. that’s predicated on the ecological conditions: Soil, temperature, precipitation, slope aspect.

      We can certainly try to create and maintain more diverse stands, especially with regard to age classes, in parts of the WUI where we are willing to invest in ongoing forest maintenance.

  3. Our ever evolving understating of the local Ecology probably hit a rough spot when we read that large Pine Beetle outbreaks are a “feature” of the Lodgepole forest. Is it OK for man to step into the mix and shape the forest to meet our desire for a less “natural” outcome? I guess it seems to me that we already have to some degree and that we just need to get better at it.

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