Managing a Killer

By Awake! correspondent in Canada

IT STALKS the forest, ignoring the young and attacking the aged. The slayer is tiny compared with its prey. It moves quickly and is not satisfied until ruination is complete. As the victim tries to force out the intruder, a life-and-death struggle ensues. Eventually the attacker wins.

Who is this foe? The attacker is the tiny mountain pine beetle, native to western North America. Its prey is the majestic lodgepole pine, common to the interior of the province of British Columbia, Canada.

Approximately 35 percent of the forested land base in the province consists of the lodgepole pine—a veritable breeding ground for the cylindrical mountain pine beetle, a mere one-eighth to five-sixteenths inch [3-8 mm] in size. Initially it targets unhealthy, overmature stands of pine. However, as the beetle population increases, the attack extends to healthy adult trees. (See the box “Mountain Pine Beetle Life Cycle.”) Recent epidemics in British Columbia have resulted in the death of 30 million pine trees in one year alone. It is estimated that enough beetles can emerge from an infested tree to kill two trees of the same size the succeeding year.

The mountain pine beetle is a natural component of the ecosystem, and along with wildfires the beetles serve to recycle lodgepole pine forests that reach maturity. Human intervention through fire detection and suppression, however, has contributed to the preservation of large areas of mature and overmature stands of timber. While this has protected wildlife habitats and migration corridors as well as forests used for recreational and industrial purposes, it has also created the need to manage the mountain pine beetle. How, though, are these tiny pests found and tracked through vast areas of wilderness? What, if anything, can be done to stem the tide of devastation left in their wake?

Detection and Tracking

Management of the mountain pine beetle starts with detection. An aerial inspection of the vast forest is made in search of trees that have turned red at the crown. Such trees indicate infestation and are easy to spot amid a blanket of green. The location of an infestation as well as the number of red trees is identified by the use of a global positioning system (GPS). Data is recorded and carefully stored in a hand-held computer. Later it is downloaded into office computers and overlaid on detailed forest cover maps by means of  powerful geographic information systems. Each infestation is then assigned a number, and a list is generated that gives the coordinates of each area. This is vital for the ground survey team, which is dispatched to verify infestation levels.

The real threat to the forest, though, is not the trees that have turned red but the green trees currently being attacked. These are generally identified by a tube of pitch surrounding the hole where the beetles have entered and by bits of frass, or sawdust, at the base of the tree. All infested trees are marked with plastic ribbons and numbered with paint. Features of the terrain and the number of attacked trees are noted as well as any other information needed to help responsible agencies decide what should be done to control the spread of the infestation.

Control Methods

If an infested area is large enough to warrant logging, another crew is sent in to map the area. A logging plan is submitted to the Ministry of Forests for approval. The logging company also becomes responsible for reforesting the area and caring for the seedlings until they can be left to grow on their own. This process not only allows utilization of the trees but also serves to control the spread of the infestation and generate new growth.

If logging is not feasible, however, single-tree treatment may be recommended. This could involve injecting pesticide into the infested tree or felling and burning it on site. The latter control method, which is done in late winter or early spring before beetles emerge, is very effective but also labor-intensive. Dale, an expert in detecting and managing such infestations, describes for Awake! the routine of a typical workday.

“The first stage involves maneuvering on single-lane roads that are also used by huge logging trucks carrying massive loads. For safety reasons we use a two-way radio to monitor road activity. When the road ends, we unload our snowmobiles and sleds and trek deeper into the forest. Our GPS and compasses are carefully packed, as well as chain saws, gas, oil, axes, radios, snowshoes, and first-aid equipment. We  traverse swamps, logged areas, and old trails through the bush for several miles. When our snow machines will go no farther, we put on snowshoes, which allow us to walk, albeit with some difficulty, through snow as deep as 50 inches [120 cm] in some places.

“The uncertain terrain makes carrying 30 pounds [15 kg] of gear somewhat challenging. Our hearts pound from exertion. How glad we are to find the site! But now the real work begins. A trained and qualified worker drops the infested trees with the precision of a marksman. Thereafter, the crew moves in and cuts the trees into manageable lengths to be burned. The bark must be completely burned to eradicate the larvae. When it is time to stop for lunch, the temperature of minus 4 degrees Fahrenheit [-20°C.] makes us appreciate our fire. We bask in its warmth and thaw out our frozen sandwiches. Then it is time to go back to work. All too soon, however, the winter sky begins to darken, reminding us that it is time to head home.”

Working in the Wild

The activities of forest workers are demanding. As these skilled individuals meet the challenges, they also take pleasure in the creation that surrounds them. This includes incredible scenery and memorable wildlife encounters. Some encounters are harmless, as when a grouse noisily flies out of the snow almost underfoot or a hapless squirrel scurries out of its burrow to run up a worker’s pant leg, creating a considerable amount of anxiety. Other encounters, however, have the potential to be deadly—one could be chased by a resident grizzly or black bear. Generally, though, dangers can be minimized through awareness and training, and workers can enjoy the wilderness environment without undue fear.

Exciting advances are being made in the use of technology to manage earth’s valuable resources. Many conscientious individuals are endeavoring to protect and preserve our precious trees through managing such things as the mountain pine beetle. Unquestionably, there is much more to learn about our wonderful forests. We long for the time when we will be able to care for them in total harmony with their original design.

[Box/Diagram on page 22]

Mountain Pine Beetle Life Cycle

In midsummer an adult female beetle bores through the bark of a lodgepole pine to the sapwood. After mating with a male, she deposits about 75 eggs. In the process she also transmits a blue-staining fungus into the sapwood to prevent pitch flow that could kill the beetles. The eggs subsequently hatch into grublike larvae that feed on the phloem (a complex tissue) of the tree. Within weeks of a beetle’s successful attack, the host tree is killed as a result of a disruption of water and nutrient flow. Larvae develop over the winter and emerge in summer to fly and attack new trees and repeat the cycle.

[Diagram]

(For fully formatted text, see publication)

Adult

Eggs

Larva

Pupa

[Pictures on page 22, 23]

Close-up of damaged tree

Infected trees

Pitch tubes