Infestations of Mountain Pine Beetles have reached epidemic levels in the Black Hills. As towering pines fall victim to an insect the size of a pencil eraser, South Dakota Game, Fish & Parks works to protect trees on forestland it owns and manages for the state’s wildlife, says Tim Bradeen, Habitat Resource Biologist for S.D. GF&P.

"This is an infestation that is threatening forest health. In areas of the Black Hills that have been hit really hard, we’ve seen an 80 to 90 percent reduction in mature pine trees," Bradeen says. "We’re working to maintain a healthy forest environment for the wildlife we manage."

Although the Black Hills are experiencing one of the worst outbreaks of Mountain Pine Beetle on record, Bradeen says this isn’t a new threat.

"The Mountain Pine Beetle has been in the Black Hills forever," says Bradeen, as he inspects a stand of trees for the insect near the Spring Creek Game Production Area.

Walking through the trees, Bradeen scans them to see if they exhibit the telltale "pitch out." A pitch out occurs when a pine beetle bores into the tree. The tree fights back by producing excess pitch to push the beetle out of the tree. Unfortunately this defense mechanism isn’t effective.

It only takes about eight Mountain Pine Beetles to kill a tree. The beetle bores into the tree to lay its eggs. This act alone doesn’t kill the tree – it’s the blue stain mold that lives on the beetle’s outer shell that does the dirty work. This mold plugs up the tree’s waterways, restricting water flow and, within a season, killing the tree.

Bradeen and the S.D. GF&P team use what they know about the insect and its habits to work to control Mountain Pine Beetle on the 9,000 acres of forestland it owns and manages for big game.

First of all, it doesn’t fly very far – only about 40 to 100 feet from the tree it hatched out of. Which is why overcrowding issues are predominantly to blame for the recent population explosion, Bradeen says.

"Dense stands of Ponderosa pine are vital to its survival," Bradeen says. "The biggest issue is overcrowding. Our open meadows have grown in so much with Ponderosa pine because in the past there hasn’t been as much thinning from commercial logging and there is a lack of fire on the landscape."

For the last 15 years GF&P has worked with contractors to strategically thin overgrown, at-risk areas of forest. When thinning is prescribed, crews work to maintain a 40-basal area spacing.

"Imagine 40 dinner plates evenly spaced on a football field. That’s what a thinned area of forest looks like," he says.

Thinning not only helps protect trees from Mountain Pine Beetle infestation, but it also improves the overall health of the forest ecology and wild game habitat, explains Bradeen.

"By thinning the trees, we’re opening up the canopy to allow sunlight to filter through the pine trees to the shrub layer – or understory – of the forest," Bradeen says. "A healthy forest ecosystem includes a shrub layer of plants like oak trees, chokecherries and aspen, which are a valuable food source for wild animals."

Stopping Mountain Pine Beetle in its tracks

If an area of the forest has more than 20 trees infested with Mountain Pine Beetles, then Bradeen and his team might decide to cut down the infected trees and chop them into 2-foot chunks. Other than using expensive insecticides, this "cut and chunk" method is one of the only ways to effectively kill Mountain Pine Beetles, says Bradeen.

"Because the Mountain Pine Beetle only has one life cycle, the best way to stop the beetle in its tracks is to kill the next generation while they are still in the larvae stage inside the tree," he says.

By felling the tree and cutting it into chunks between the months of November and March – when the Mountain Pine Beetle is still in its larvae stage – they are effectively robbing the larvae of its food supply and killing it before it is mature enough to emerge from the tree.

Bradeen says this method has proven to be 80 to 90 percent effective in stopping the infestation of Mountain Pine Beetles.

In 2011 S.D. GF&P invested $40,000 in controlling Mountain Pine Beetles. Their efforts are paying off. A recent study in Custer State Park showed that in managed areas of the forest where thinning and cut and chunk techniques were implemented, six out of 10 trees were saved; compared to unmanaged areas of the forest where nine out of 10 trees fell victim to death by the Mountain Pine Beetle.

Like all projects implemented by South Dakota Game, Fish & Parks to manage habitat and wildlife, only license dollars are used.

By Lura Roti for South Dakota Game, Fish & Parks

Tim Bradeen, Habitat Resource Biologist for South Dakota Game, Fish & Parks. Photo courtesy of S.D. GF&P.

     

Tim Bradeen, Habitat Resource Biologist for South Dakota Game, Fish & Parks, uses an ax to examine the cambium layer of this tree. He will follow the Mountain Pine Beetle tunnels under the bark layer of the tree to look for Mountain Pine Beetle larvae. Photo courtesy of S.D. GF&P.

      

When a tree is infested with Mountain Pine Beetles, its natural defense mechanism is to create a "pitch out."  A pitch out occurs when a pine beetle bores into the tree. The tree fights back by producing excess pitch to push the beetle out of the tree. Photo courtesy of S.D. GF&P.

       

        

When a tree is infested with Mountain Pine Beetles, its natural defense mechanism is to create a "pitch out." A pitch out occurs when a pine beetle bores into the tree. The tree fights back by producing excess pitch to push the beetle out of the tree. Photo courtesy of S.D. GF&P.
Infestations of Mountain Pine Beetles have reached epidemic levels in the Black Hills. Photo courtesy of S.D. GF&P.