Researchers, US Forest Service officers study forests after pine beetle infestation

Posted: July 10, 2013

Source: Steamboat Today

Forest killed by mountain pine beetle near steamboat springsSteamboat Springs — Routt National Forest lost about 615,000 acres of trees to the bark beetle epidemic. Medicine Bow National Forest had about 650,000 acres of dead trees, according to U.S. Forest Service spokesman LarrySandoval.

Now, the epidemic has leveled off, and officials are stepping in to take stock of the situation.

A group of Forest Service officers and university researchers gathered Tuesday night at Bud Werner Memorial Library to share what’s been learned in the wake of the epidemic and how the forests are moving forward.

University of Wyoming professors Brent Ewers and Dan Tinker gave presentations about the research that’s gone on in beetle-killed areas, and Sandoval spoke about what his office has been doing to manage Medicine Bow-Routt National Forest.

Ewers presented data about not only the cycle that goes on in forests from when the infection starts to when the trees die but also the effects on soil and watersheds.

The extra nitrogen that passes into the soil from dropped needles and litter is absorbed by the healthy trees that are left standing, according to Ewers. Bark beetles also prefer larger trees, he said, leaving smaller trees of the same age less likely to be infected with the blue stain fungi they carry. The growth rate of these smaller trees can increase as nitrogen is more plentiful and they aren’t crowded out by larger trees.

Partially because of the residual trees absorbing more, studies have shown that the extra nitrogen is not making it into streams, Ewers said.

The extra water that might be expected from more snow making it to the ground in the absence of large trees isn’t showing up in the rivers either, Ewes said. The finding is controversial, he said, but there’s more research planned as the University of Wyoming has received grants that will enable it to use better tools to track the water.

As Tinker pointed out multiple times during his talk, there’s still a lot of uncertainty in the science. But there also are many positives to take away from what’s been observed even recently.

Unlike forest fires, a stand disrupted by beetles doesn’t have to wait for seedlings, Tinker said. It has younger trees that can start advanced regeneration right away. And, like Ewers also mentioned, trees that no longer have to deal with dense overstory might grow faster.

What might change going forward for forests that were heavy on lodgepole pines before the mountain pine beetle epidemic is a shift to a more diverse forest composition, according to Tinker. In his work in the Medicine Bow National Forest, Tinker said, he’s seen a shift to subalpine fir in the seedlings.

Questions such as the effects on growth of harvesting timber and the potential for more severe fires remain hard to nail down.

“The body of literature is building,” Tinker said. “And we’re learning more and more about it.”