Forests Recover Quickly After Bark Beetles Attack

So, they’d recover quickly after anthropogenic disturbances, too, I presume.


Forests Recover Quickly After Bark Beetles Attack

SAN FRANCISCO — A forest ravaged by the “red hand of death” — also known as a bark beetle attack — recovers quickly with little ecosystem damage, scientists said here today (Dec. 9) at the annual meeting of the American Geophysical Union.

The potential effects of massive tree die-offs in Western forests have been a concern since a sudden uptick in bark beetle attacks in the late 1990s. A species called the mountain pine beetle is one of the primary culprits, leaving large swaths of forest dying of a fungus carried by the tiny insects. Beetle outbreaks have hit more than 30 million acres in the western United States and Canada, according to the National Science Foundation.

Forests look awful after a beetle attack, but the wound isn’t as terrible as it looks, according to two separate studies by researchers from the University of Wyoming and the U.S. Forest Service (USFS).

In Wyoming’s Medicine Bow National Forest, botanist Brent Ewers of the University of Wyoming examined whether tree deaths sent more water into streams (because there is less vegetation to suck up precipitation), as well as released additional carbon and nitrogen from dead, decaying trees. Even when up to 80 percent of trees were killed by beetles, Ewers and his colleagues saw little evidence of these worrisome effects.

“Even though bark beetles have an enormous visual impact, the forest is resilient to the attack,” Ewers told LiveScience.

And in Colorado’s Front Range, in the Rocky Mountains above Denver, pine beetle infestations don’t add extra nitrogen to waterways that eventually drain to the city, according to a study led by USFS research scientist Chuck Rhoades.

It turns out that because beetles don’t kill all the trees at once, the survivors gobble up extra water and nutrients freed up by the fatalities, both studies found. In four different study sites, 40 percent of older trees grew two times faster in the years after bark beetles munched through the forest, Rhoades and his colleagues found. In Wyoming, the understory plant cover — which includes new tree seedlings, shrubs and flowers — more than doubled, Ewers found.

Turns out that both the surviving trees and new growth can eat and drink all the free water and fertilizer in the forest. On the small scale, there may be local increases in stream flow, carbon or nitrogen, but overall, there is very little change after a bark beetle infestation, Ewers said.

“Even though the bark beetle visual impact is really impressive and striking, there’s many things going on in that forest that makes it resilient to the attack, and so those compensating mechanisms result in little impact in what the ecosystem itself is doing,” Ewer said.

7 thoughts on “Forests Recover Quickly After Bark Beetles Attack”

  1. Yep, and the West Fork Complex burned extraordinarily spectacular, just like the media outlets wanted, when the Forest Service wanted to burn more than just those 150 acres, after 9 days of burning. Darn those Feds for the “destruction” of more than 100,000 acres of dead forests, at a cost of over $30,000,000. *smirk*

  2. So, the drainages didn’t burn. Wonder what the results on water yield and nitrogen will be after a fire — and yep, those beetle woods will burn. With bated breath, I remain…..

  3. Steve: Thanks for posting this.

    So, scientists and researchers are finding that forests quickly recover with little ecosystem damage following a bark beetle attack….. (something the enviro community has been claiming for years).

    And you want to extrapolate these scientific findings about a natural disturbance process from a native species and presume that forests would recovery quickly after anthropogenic disturbances (such as logging and associated road building/soil compaction, etc too?


    • Matthew,

      I wrote “they’d recover quickly after anthropogenic disturbances, too, I presume” with my tongue positioned in my cheek. Of COURSE forests recover on their own, from all kinds of disturbance, given time. There may be “little evidence of these worrisome effects” to specific ecosystem functions, but in Colorado’s Front Range, in the Rocky Mountains above Denver, where beetles killing forests results in “little ecosystem damage” and aren’t “as terrible as [they] look,” there are huge consequences to sitting back as letting nature take its course.

      “Natural” recovery is appropriate in some areas, regardless of the type or origin of disturbance (a generalization, sure), and anthropogenic recovery (a coined phrase?) is appropriate in other areas. A combination of the two might work in some cases. To generalize again, I prefer active forest management — multiple-use management — outside of wilderness areas and other reserves. If we didn’t have a need for all of those multiple uses, “letting nature take its course” would be fine. But because people need both forests and forest products, we need to practice forestry.

      Sorry for the rant. The work the researchers did is great, but I figure it may be used by others to promote passive management in areas there active management is needed.

  4. Here is one final result of bark beetle attacks on the Eldorado NF.,-120.309219&spn=0.059951,0.132093&t=h&z=14 There were massive bark beetle attacks and some limited helicopter salvage logging before a wildfire “re-balanced” everything. After the wildfire, helicopter salvage logging harvested the snags. This Freds Fire is “bookended” by other wildfires, east and west. This area was dominated by fire-adapted old growth pines, and has been replanted. No, I don’t think that this forest recovered quickly after a bark beetle attack, and the original insect mortality provided ample fuels that resulted in this higher intensity burn.

      • If you look westward, you can see the section lines from checkerboarded land ownership. Most of the private land is Sierra Pacific Industries. Yes, there were some great old growth ponderosa pine forests there, on Forest Service lands. I walked all over that steep helicopter ground, back in the early 90’s.

        I would also go as far as saying that bark beetle mortality had a significant role in the burn intensity on the Angora Fire, too. I think we have yet to see the final impacts of not salvaging timber in the Tahoe Basin, and the fuels from the 90’s bark beetle bloom will persist for decades there.


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