FIRE CASE STUDIES
SPECIES: Vaccinium vitis-idaea | Mountain Cranberry 



CASE NAME : 
Black spruce, Fairbanks, Alaska


REFERENCE : 
Viereck, L. A.; Foote, J.; Dyrness, C. T.; [and others]. 1979 [113]


SEASON/SEVERITY CLASSIFICATION : 
summer/moderately severe

Unit 2 - burned July 22, 1976
Units 1L, 3, and 4L - burned August 26, 1976


STUDY LOCATION : 
The study site is within the Washington Creek Fire Study and Training
Area located approximately 22 miles (40 km) north of Fairbanks, Alaska.


PREFIRE VEGETATIVE COMMUNITY : 
The preburn community was an unevenly spaced stand of black spruce
(Picea mariana) approximately 70 years old.  The forested area was
interspersed with shrub-dominated openings.  The forest understory was
made up of various shrubs, herbs, mosses, and lichens.  Green alder
(Alnus viridis ssp. crispa), paper birch (Betula papyrifera), and
willows (Salix spp.) were scattered throughout the area.  Mountain
cranberry (Vaccinium vitis-idaea), bog blueberry (V. uglinosum), and bog
Labrador tea (Ledum groenlandicum) were common in the small clearings.
Lichen mats carpeted the open areas.  Moss was abundant throughout the
community; cover ranged from 72 to 85 percent.


TARGET SPECIES PHENOLOGICAL STATE : 
Not reported.


SITE DESCRIPTION : 
      Elevation:  1,700 feet (520 m)
      Aspect:     slopes to the southeast
      Soil:       shallow Fairplay silt loam with shattered bedrock and stones
                  at 8 to 20 inches (20-50 cm) in depth 
      Climate:    average monthly precipitation-
                  April - 0.3 inch (6.4 mm)
                  May - 0.7 inch (18.6 mm)
                  June - 1.3 inches (35.3 mm)
                  July - 1.8 inches (46.7 mm)
                  August - 2.2 inches (55.9 mm)

                  No permafrost was encountered.


FIRE DESCRIPTION : 
      Unit 2:     fuel stick moisture - 6.6 percent
                  relative humidity - 32 percent
                  wind speed/direction - 0-5 miles/hour (0-2.2 m/s) from SSE
                  temperature - 76 degrees F (24 degrees C)

Unit 2 was ignited at the southeastern corner.  The fire soon began to
crown and moved throughout the unit within 7 minutes.  The fire was
particularly intense at the center.  The fire was hot at the 0 to 9 foot
(0-3 m) level, but did not burn hot within the forest floor.
Temperatures reached approximately 249 degrees F (121 degrees C) at 2
inches (5 cm) above the ground.

      Units 1L, 3, and 4L:
                  fuel stick moisture - 6.6 percent
                  relative humidity - 40 percent
                  wind speed/direction - 6 to 8 miles/hour (2.7-3.6 m/s) 
                        from the SSE
                  temperature - 66 degrees F (19 degrees C)

Unit 1L was ignited at the southeastern corner.  The fire began to crown
within 1 minute, but the burning of crowns was spotty.  The unit was
covered by the fire within 9 minutes.  The fire burned into the organic
layer for several hours, and in spots, smoldered and flamed for several
days.  Fuels were added to the unit prior to the burn.  Loaded fuel was
estimated at 29,720 pounds per acres (26,500 kg/ha).

Unit 3 was ignited at the eastern corner.  Spotty torching occurred but
the fire was mainly a slow-moving ground fire.  The fire burned across
the unit in 29 minutes.  The ground fire was not very intense, but did
continue for several days.  Approximately 40 to 50 percent of the ground
vegetation was moderately to heavily burned.  Although much of the area
was lightly burned, an estimated 40 percent of the unit burned to
mineral soil.

Unit 4L was ignited at the middle of the southeastern boundary.  Fire
completed its run within 6 minutes.  Several parts of the unit
experienced a very hot crown fire.  The fire burned into the organic
layer in some areas, and soil temperatures reached 163 degrees F (73
degrees C).  Approximately 70 percent of the ground vegetation was
heavily or moderately burned.  Supplemental fuels were added to the unit
prior to the fire.  Loaded fuel was estimated at 15,600 kg/ha.


FIRE EFFECTS ON TARGET SPECIES : 
Aboveground vegetation, including mountain cranberry, was totally
destroyed in units 2, 3, and 4L.  Some unburned portions of aboveground
vegetation remained on unit 1L.  An inventory conducted in September,
revealed no regrowth on plots burned in August (Units 1L, 3, and 4).
Sprouts of bluejoint reedgrass (Calamagrostis canadensis) and Scouler
willow (Salix scouleriana) were observed on unit 2 which had been burned
in July.  No mountain cranberry was reported.


FIRE MANAGEMENT IMPLICATIONS : 
Summer fires can temporarily remove ericaceous shrubs such as mountain
cranberry.  At least several years may be required before preburn cover
is reached.

Related categories for Species: Vaccinium vitis-idaea | Mountain Cranberry