Spruce Beetle Outbreaks On The Kenai Peninsula

On Alaska's Kenai Peninsula, a forest nearly twice the size of Yellowstone National Park has been dying. "Century-old spruce trees stand silvered and cinnamon-colored as they bleed sap," from spruce bark beetle infestations spurred by rising temperatures, wrote reporter Tim Egan of The New York Times (June 16, 2002, A-1, June 25, 2002, F-1). During 15 years (1988-2003), 40 million spruce trees on the Kenai Peninsula have died (Whitfield, 2003, 338). The beetle infestations have reached Anchorage, where "[v]isitors flying into the city's airport cross islands covered with the bristling, white skeletons of dead trees that are easily visible through the plane windows" (Lynas, 2004, 60).

Alaskan author Charles Wohlforth described the coming of the bark beetles:

On certain spring days in the mid-1990s, clouds of spruce bark beetles took flight among the big spruce trees around Kachemak Bay, 120 miles south of Anchorage. They could be seen from miles away, rolling down the Anchor River valley. People who witnessed the arrival sometimes felt like they were in a horror film, the air thick with beetles landing in their eyes and catching in their hair, and knew when it happened that their trees were destined to turn red and die. (Wohlforth, 2004, 238)

The six-legged spruce beetle, which is about a quarter-inch long, takes to the air in the spring, looking for trees on which to feed. When beetles find a vulnerable group of trees, they will signal to other beetles "a chemical message," Holsten said. They then burrow under the bark,

Global Warming Spruce Tree

A spruce bark beetle (Jeff Dixon)

feeding on woody capillary tissue that the tree uses to transport nutrients. Healthy spruce trees produce chemicals (terpenes) that usually repel beetles. The chemicals cannot overwhelm a mass infestation of the type that has been taking place, however (Egan, 2002, F-1). As a spruce dies, green needles turn red and then silver or gray. According to Egan's account, "Ghostly stands of dead, silver-colored spruce—looking like black and white photographs of a forest—can be seen throughout south-central Alaska, particularly on the Kenai. Scientists estimate that 38 million spruce trees have died in Alaska in the current outbreak" (Egan, 2002, F-1).

More than 4 million acres ofwhite spruce trees on the Kenai Peninsula were dead or dying by 2004 from an infestation of beetles, the worst devastation by insects of any forest in North America. Beetles have been gnawing at spruce trees in Alaska for many thousands of years, but with rapid warming since the 1980s their populations have exploded (Egan, 2002, F-1).

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Responses

  • matthias
    What species of spruce trees on the kenai peninsula?
    8 years ago

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