Fire and water don’t mix. This is especially true in Southeast Alaska. But when the conditions are right, forest fires can blacken local forests in ways unfamiliar to most.
According to Seth Stransky, senior firefighter with the U.S. Forest Service on the Juneau Ranger District, it does happen and these burns are a lot different than those seen in Interior Alaska or down South.
“They burn underground,” he said. “Almost like a cigarette butt.”
Typically, there are no eye-catching flames ripping through the crown of the forest and no tell-tale plumes of smoke billowing upward like anvil clouds. But according to Stransky, who gained experience fighting fire in Colorado, huge square footages can be burned in dry areas.
Wildfires in Southeast forests, which are located in an area called the perhumid zone, are fueled by duff, the cast-off tree needles, pinecones, alder leaves, dead moss and lichens that accumulate over many seasons. In some areas, Stransky said, the duff layer could be three- to four-feet deep.
Patti Krosse, a forest ecologist on the Tongass National Forest, said when conditions are right — during a warm summer or dry period — the top-most layer can dry quickly. Like a mouse finding its way through a maze, a smoldering fire could follow fuel and creep deeper into the forest, even eating away at anchoring root systems.
“It’s the dry layers that can facilitate underground fire movement,” Krosse said. “It does lead to subsidence in some areas and to trees falling down and such.”
The idea of a rain forest wildfire is a foreign one to most. At least in Southeast Alaska; they do happen frequently in rain forests of the Pacific Northwest, according to Dave D’Amore, a research scientist on the Juneau Ranger District. But, in an ecosystem that gets roughly of 13.5 feet of rain annually, it’s easy to understand why fire is not a naturally occurring part of local forest ecology.
“We just have wet soils,” Krosse said. “Even during a really dry season, you will get dryness with depth — we’re talking a foot at most. The water table will lower, but it doesn’t completely dry out.”
Krosse said regional rain forest wildfires do not reach a level of intense severity because they are short-lived. It doesn’t take long before fire reaches a wet area, she said.
“The biggest thing, however, with fires in Southeast Alaska, is the removal of dry duff because that is so nutrient rich,” she said.
According to Krosse, controlled burns in the Ketchikan area saw a five- to 10-year delay in regeneration.
“In the last three seasons I have worked in Southeast, all fires have been man-made, except one.” Stransky said. “People leave their fires burning and assume it will be fine because it rains a lot.”
But, according to Stransky, it takes just two days of sunny weather to turn that otherwise moist organic material into ideal fire fuel. Sun-filled days also send Alaskans outdoors. This means more campers and more campfires that, if not tended to properly, can start a forest fire. In fact, the Juneau area has already experienced one wildfire this season.
“We had one on Portland Island on April 29,” Stransky said. “It burned about a quarter acre. Someone must have been burning a chair or couch and the wind pushed it through the beach grass and to the forest edge.”
Luckily, he said, many of the fires are spotted quickly by the keen eye of a local pilot or by recreationalists. This means the fire crew stationed here, a Type 6 Engine crew and a Type 2 crew, can respond and contain the burn quickly.
On average, the acreage remains small, hovering around a quarter of an acre.
But, Stransky said, fires always have the potential to get big.
Last year, Southeast experienced “a big one.” According to Stransky, a rare lightning strike ignited a fire near Hoonah that crowned and burned 7 ½ acres before response teams put it out.
Lightning-caused fires are rare in this part of Alaska, but they do happen. According to a graphic provided by the USFS, 24 fires were caused by lightning from 1989 to 2010. For comparison, lightning caused the ignition of 330 fires in the state of Alaska in 2010, and 1,110 fires were lightning-caused in the Northwest last year, according to the National Interagency Coordination Center.
In a geographical area with massive forests built upon glacial bedrock, one may be led to wonder how fires affect the stability of soils and root systems.
Two years ago, according to Stransky, a wildfire blackened a rocky point roughly halfway between Juneau and Echo Cove. What remains now is a tangled mass of root wads, downed trees, exposed bedrock and a few green shoots of fireweed.
“Any time organic material is disturbed, that’s contributing to the instability of a tree’s roots,” Krosse said. “The other thing about removing organic material is that it is susceptible to the effects of rain, erosion and such, things we don’t typically see around here.”
She said the soil most susceptible is called McGilvery soil, and it’s very common hillside soil in Southeast. It can be extremely productive, as well, because it’s one of the only types of well-drained organic soils in the area. But, it’s just a bunch of moss and litter over bedrock.
“If a fire goes through that type of soil,” she said, “the entire forest mantle is essentially removed. You won’t get landslides, but you may find material in drainages and definitely blow-down. You will not get regeneration. If you do, it will take a long time for (vegetation) to come back and will depend on how the soil reforms.”
According to Stransky, June and July are the busiest time for Juneau Ranger District firefighters. They access fire locations by boat, plane or land, depending on the location. Although campfires are allowed, it is criminal to leave fires unattended and to build a fire without a fire guard or barrier.
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