Who Loves Fire?
by Sarah Walker
hat’s behind the scenes in those endless stands of lodgepole pine along the mountain ridges of K’useyneiskit? Why would a bird evolve camouflaging feathers to blend in with burned forests? What purpose would heat sensors serve for a beetle?
Black-backed woodpeckers travel long distances to find recently burned forests.
The bird with black feathers is the black-backed woodpecker,1 one of eight Idaho woodpeckers that forage on wood-eating beetles in burned forests (Meriwether Lewis noted the hairy, Lewis’s, and pileated woodpeckers, and the northern flicker). Black-backs are drawn to the unique foraging opportunities in recently burned forests, and are able to detect them from great distances. They seek burned forests where most of the standing dead trees are nine inches in diameter or larger and still have bark, and where long, white, succulent larvae of wood-boring beetles belonging to the genus Melanophila (mell-ann-AH-fill-a, “black-loving”) live under the bark. A large supply of dead trees and beetles provides enough support for these specialized birds to mate and raise another generation. While raising a family, a black-backed woodpecker may consume over 13,000 beetles in a year.
Besides reducing populations of wood-eating insects, woodpeckers create nesting sites for many forest dwellers. Each spring, they excavate new nesting and roosting cavities in dead trees. The empty holes from previous years’ nests become available for the many species of birds and mammals called “secondary cavity nesters”—mountain bluebirds, chickadees, tree swallows, kestrels, flying squirrels, and pine martens, to name a few.
Insects that seek out forests stressed by fire are called “pyrophilic” (pie-row-PHIL-ik, “fire-loving”) and may have special sensors for detecting burned forests, even if they are many miles away. Some beetles have infrared sensors beneath their wings; others have smoke sensors on their antennae. The Air Force is intrigued by the superior capabilities of these sensors for detecting infrared radiation, and military research has furthered our knowledge of how they work.
An adult long-horned wood-borer, whose larvae are a favorite food of black-backed woodpeckers.
When we first see the newly burned ground surface of a stand-replacement fire, it appears as a desolate scene of ashy, burned soils with scattered remains of shiny, blackened, wood. But signs of life appear within a few weeks from “legacies” left by fire, like standing dead trees, isolated green trees, or surviving seeds and spores.
Seeds of nearby unburnt conifers blow onto the burned site. Exposed on the bare surface, they are easier to find and collect, and small mammals take advantage of this. Chipmunks can be seen scurrying around on ashy soil.
Roots that survive deep underground have sprouting potential. Grouse whortleberry2 reappears in this way. Its upper parts may be burned during a fire but if its roots survive in the soil, it can resprout. Its small shiny leaves carpet the floor of some of the lodgepole forests along K’useyneiskit, and its tiny, sweet, red berries are sought by grouse.
Lodgepole pine seeds sometimes come in “serotinous” (sir-AH-tin-us, “closed”) cones sealed with resin so thick that high temperatures, as from fires, are required for them to open and release seeds. This is one way that lodgepole pines can repopulate burned areas.
Haircap moss colonizing a burned area.
A closer look at the ground a year after a stand-replacement fire reveals some surprises. What’s a moss doing out in the bright sun? Some species of haircap moss3 can colonize burned areas, appearing as a dark orange or red carpet of thickly growing plants.
Lewis and Clark didn’t mention smelling smoke from forest fires or seeing lightning during their trips through the Bitterroot Mountains in Idaho. But today’s summertime traveler probably will. Careful observers can search for clues to the interesting birds, animals, insects and plants that appear on the scene after a forest burns.
1. Picoides arcticus (Pik-OY-deez, “resembling a woodpecker”; ARK-ti-kus, “of the north”).
2. Vaccinium scoparium (vax-SIN-ee-um sko-PARE-ee-um), “broom-shaped blueberry bush.”
3. Polytrichum sp. (Poh-LIH-trih-kum), “many hairs or bristles.” The abbreviation “Sp.” stands for “specific epithet.” Every plant, animal, bird, insect, and fish has a pair of scientific names: first the genus name, then the specific epithet, much like our own paired names. When the specific epithet is uncertain, or when one is referring to several members of the same genus, “sp.” is substituted.
"Bird Conservation Plan: Burned Forest," http://www.biology.umt.edu/landbird/mbcp/mtpif/burned.htm, (Nov. 3, 2003).
Richard L. Hutto, “Composition of Bird Communities Following Stand-Replacement Fires in Northern Rocky Mountain (U.S.A.) Conifer Forests,” Conservation Biology (October 1995), Vol. 9:5, pp. 1041-1058.
Evan Frost, "Of Wildfires and Woodpeckers," Methow Naturalist (Summer 1996), Vol. 1:2, p. 1.
Mike Hillis, A. Jacobs, and V. Wright, "Black-backed Woodpecker Assessment" http://www.fs.fed.us/r1/cohesive_strategy/integration/wildlife/R1_bbwo_assessment.htm, (Oct. 31, 2003).
Susan Milius, "Why Fly into a Forest Fire? It's One Way to Meet a Lot of Great Bugs," Science News (March 3, 2001), V. 159, 140-141.
Deborah Richie Oberbillig, "Black-backed Woodpeckers Depend on Burned Forests" (September 2000), USDA Forest Service Northern Region News Release.
Supported in part by a grant from the Idaho Governor's Lewis and Clark Trail Committee