Sunday, October 29, 2017

Mixed Severity Fire in the Marble Mountains. Hot fire and Fire Refugia


A sunset from upper Dollar Meadows in the Wallow Fire on the Little North Fork of the Salmon River.
I recently hiked into the western portion of the Wallow Fire to monitor the fire effects and document the post-fire mosaic. I hiked the Garden Gulch Trail to Chimney Rock and then out to English Peak and Hancock Lake at the northwest fire perimeter. The Wallow Fire started on August 11, 2017 with a flash of lightning near Bear Wallow Peak, deep in the Marble Mountain Wilderness. After burning for weeks in the North Fork of the Salmon River, the fire jumped the ridge and burned into the Little North Fork drainage on August 29, 2017. Over the course of one week, 46,668 acres burned in a large, wind-driven run up the Little North Fork and into the headwaters of adjacent drainages, including Steinacher Creek, Crapo Creek, and tributaries of Wooley Creek. This week-long period accounts for 70% of the acres burned in the Wallow Fire.

Little North Fork of the Salmon River after the Wallow Fire.

The Wallow Fire's big western run was associated with significant wind/weather driven fire event. From August 29 to September 5, weather and terrain overwhelmed the adjacent 2006 and 2008 fire footprints, which would have otherwise slowed the fires spread. The steep slopes and deep canyons funneled the wind, throwing embers across the landscape. The Wallow Fire spotted up to two miles ahead, creating roughly 40 spot fires in upper Little North Fork, Steinacher Creek, Crapo Creek and numerous others drainages. The spot fires merged into a large concentration of weather-driven, high-severity fire at the western fire perimeter. 

As abruptly as the big, hot run began, it died down when the weather shifted. With a little rain and a significant increase in relative humidity, the raging fire smoldered itself out. Now that the smoke has cleared and the effects can be seen, it is clear that the Wallow Fire will leave a lasting impact on the Little North Fork and surrounding watersheds.
The Wallow Fire burned hot in upper Crapo Creek. When the weather changed and the wind became still the fire abruptly died, creating a dramatic transition between high-severity burn patches and unburned areas.

I hiked into Upper Crapo Creek at the southwest margin of the fire. The forest and chaparral on upper Crapo burned hot, yet the fire stubbornly refused to enter the adjacent fire footprint. Even the raging, wind-driven inferno could not penetrate the recently burned slopes.

The ridgeline above was sparse, black and fire swept, dividing the Little North Fork from Crapo Creek. Chimney Rock, a sharp, white summit stands at the terminus of the long granitic ridgeline, rising above the dark snags, soot and ash of the Wallow Fire. Deep canyons fall at both sides of the ridge, transitioning from snag fields to mixed conifer forest.
 
A view down the Little North Fork of the Salmon River after the Wallow Fire.

A small island of unburned hemlock, Brewer's spruce, western white pine, huckleberry and high mountain heather cling to the east-facing cliffs of Chimney Rock. The landscape is sparse, rocky and dramatic. Below, the Dollar Meadow Basin was heavily burned. Scattered western white pine, hemlock and incense cedar punctuate the bare granite slabs — mostly, the fire burned the forest bare. The small meadows were cleared by the fire, reducing conifer encroachment and connecting the long isolated meadow habitats. Much of the forest surrounding Dollar Meadows lost its struggle with the Wallow Fire and it appears the meadows may have won.

To the north, hot fire burned above Hamilton Camp, torching the true fir forest at the edge of the wet meadows. The fire cooled at the saddle and left a mosaic of burned forest and green, living trees. Heading northeast along the long granitic ridgeline between Hamilton Camp and English Peak you enter slopes that had heavily burned in 2006 Uncles Fire and re-burned in the Wallow Fire. The Wallow Fire rushed through this section with a vengeance, turning the snags black with charcoal, consuming the understory fuels and leaving a powdery layer of ash across the surface of the soil.
The ridge between Hamilton Camp and English Peak has transitioned to complex, early-seral vegetation.

Before the Wallow Fire the area supported extensive snag forests, chaparral, young conifer regeneration and dry bunchgrass and buckwheat clearings. The Wallow Fire uniformly scorched the majority of the ridge, leaving only occasional islands of young conifer regeneration, a few stands of more mature trees, and unburned bunchgrass clearings. The south-facing slopes are now blackened and will transform into yet another unique ecosystem. 

In some places snowbrush, huckleberry oak and other shrubs are  already regenerating, in other places fields of bracken fern, fireweed and dry grassy clearings are already returning. Large sections of regenerating forest were burned clean by the Wallow Fire, resetting the ecological clock.


An early-seral bunchgrass opening regenerating from the 2006 Uncles Fire.
The views are spectacular, stark, and humbling. They are also intriguing. How will the ecosystem respond? What will regenerate in this large, blackened area? How will the reburn affect stand development and species composition.

 In time, the biodiversity of the burn will become more apparent and the rejuvenation will surprise us with its abundance and beauty. From ashes, this habitat will rise, changed, but connected to its past and thriving in its own way. 

I can now envision the buckwheat fields, rock gardens, fireweed patches, dry bunchgrass clearings, vibrant green conifer regeneration, and yes, the brushfields that will grow from the blackened snags and downed wood, creating habitat and life. Pollinators, songbirds, butterflies, woodpeckers, elk, bear and wildlife of all sorts will visit these clearings for sustenance. What some might see as disaster is a new opportunity for many species in the complex, diversified conifer forests of the Klamath-Siskiyou. 

The large, high-severity burn patch extends from near Hamilton Camp to Snowslide Gulch and up to the flank of English Peak where meadow and forest alike are unburned. Rustic Tom Taylor Cabin burned to the ground in the firestorm, but English Peak Lookout, perched high in the rocks, remained safe from the flames.

On the other side of the ridge, the fire behaved very differently.  Despite the large run up Little North Fork, the North Fork of the Salmon River burned at low to moderate intensity. The Wallow Fire burned streaks in the forest and brush at the North Fork's headwaters, often dying out in the rocky cliffs, ledges and steep granite ramps above. Much of the area was either unburned or underburned, leaving the canopy intact and the mosaic only gently touched by visible fire effects.
A view from the ridge near English Peak into the beautiful English Lake Basin. The fire burned at low to moderate intensity in the North Fork of the Salmon River. The steep, granitic headwall acted as fire refugia, providing the southern-most Pacific silver fir an unburned island high in the rock.

Out the ridge, towards Diamond Lake, and the out towards Hancock Lake, lies the southern-most stand of Pacific silver fir. Pacific silver fir grows in cool, moist and often very snowy habitats. They are found in only two locations in the Klamath Mountains, one here, near Hancock Lake and another near Copper Butte and Black Mountain on the Siskiyou Crest.


Pacific silver fir near Diamond Lake.
Although the species is very sensitive to fire, it also grows in highly effective fire refugia. The southern-most population exists within a cool, moist island of forest surrounded by rocky cliffs and ledges. The hemlock, red fir and Pacific silver fir grow in dense, mature groves embedded within rock outcrops and wet meadows. Numerous recent fires have burned to the edge of this stand, but have yet to penetrate the rocky kingdom in which this population exists. The Wallow Fire burned all the way around the population, demonstrating the effectiveness of the fire refugia in which the Pacific silver fir live.

Pacific silver fir and many of our other fire sensitive species such as Alaska yellow cedar, subalpine fir and Brewer's spruce have developed an avoidance strategy, clinging to the very habitats fire cannot penetrate. They do not develop thick, insulating bark or high, fire resilient canopies; they do not thrive in the face of fire like knobcone pine, lodgepole pine or chaparral, instead they avoid fire by exploiting cool, moist and rocky, high mountain habitats. I often judge the effects of a fire on how well the fire sensitive species persist in the post-fire environment. In the case of the Wallow Fire, I have seen significant viable populations of subalpine fir, Brewer's spruce and Pacific silver fir avoiding the flames in their rugged mountain haunts. Clinging to the rocky, north-facing slopes where fire struggles to burn, our ancient relict conifer species seem to be doing just fine. 
Hancock Lake

2 comments:

  1. Thanks Luke. I really appreciate your knowledge and perspective.

    ReplyDelete
  2. Thanks Luke. I really appreciate your knowledge and perspective.

    ReplyDelete