FIRE CASE STUDIES
SPECIES: Ceratodon purpureus | Fire Moss 



CASE NAME : 
The effects of fires on black spruce forests 


REFERENCE : 
Dyrness, C. T.; Norum, R. A. 1983 [9]


SEASON/SEVERITY CLASSIFICATION : 
Seven units of black spruce (Picea mariana)-feather moss forest were
experimentally burned under various fuel moisture conditions during the
summer of 1978.  Surface woody fuels were sparse and the principal
carrier fuel was the forest floor (largely mosses and their
decomposition products).  Forest floors after burning comprised a
small-scale mosaic of unburned, scorched, lightly burned, moderately
burned, and heavily burned conditions.


STUDY LOCATION : 
The area lies within the W 1/2 sec. 12, NE 1/4 sec. 13, T.4 N, R.2 W, of
the Fairbanks Meridian.


PREFIRE VEGETATIVE COMMUNITY : 
The prefire vegetation was a typical open black spruce/feather moss
forest community.  The mature, open black spruce tree layer comprised a
mosaic of two dominant age-classes of about 85 and 140 years.  Some of
the seven units burned had small groups of aspen (Populus tremuloides)
and scattered paper birch (Betula papyrifera).  The tall shrub layer was
represented by scattered clumps of American green alder (Alnus crispa),
willows (Salix spp.) and prickly rose (Rosa acicularis).  The most
common low-growing shrubs were mountain cranberry (Vaccinium
vitis-idaea), bog blueberry (V. uliginosum), crowberry (Empetrum nigrum)
and Labrador tea (Ledum groenlandicum).  The herbaceous layer was very
sparse.  Virtually the entire forest floor was covered with a thick
layer of feather mosses.


TARGET SPECIES PHENOLOGICAL STATE : 
NO-ENTRY


SITE DESCRIPTION : 
The total burned area covers about 32 acres (13 ha).  The elevation is
1,575 to 1,706 feet (480-520 m).  The slope is 10 to 15 percent and the
aspect is generally southeast to south from a main ridge running
southwest to northeast.  The position of the fires was on the upper
third of the slope.  The soil is silty loam, somewhat poorly drained in
shallow loess over schist bedrock.  Before the fire, a forest-floor
layer 8 to 12 inches (20-30 cm) thick was present.  The mineral soil is
made up of a very dark-brown silty loam surface horizon underlain by a
yellowish-brown, stony (30-50 percent by volume), silty loam subsoil.
Bedrock was generally within 29 inches (75 cm) of the surface.


FIRE DESCRIPTION : 
Seven units of approximately 5 acres (2 ha) each were burned
individually between July 19 and August 8, 1978.  The down, dead, woody
fuels contributed little to fire behavior or subsequent fire effects.
Fire behavior on the seven units varied from slowly moving surface fires
to rapidly advancing crown fires.  All fires became crown fires on parts
or all of each unit.  The crown fires were passive, making the
transition after hot surface fires had passed beneath the trees.  The
surface fires determined the rate of spread, and the crown fires
followed, with flames commonly reaching 50 feet (15 m) or more.  Most of
the units were completely covered by fire and had burned down to glowing
combustion within an hour after ignition.  Weather conditions during the
fire at the seven units were as follows:

                                     Unit
                        1     2     3     4     5     6     7

Temperature (deg C)     23    21    24    21    22    21    26
Relative humidity       42    33    30    54    42    33    36
Wind (mph)              1-4   5-8   4-6   1-2   3-6   3-5   3-5
Wind direction          SSW   SW    SW    SW    SSW   SW    SSW
Rate of spread (ft/min) 1.5   3.7   3.8   1.0   4.0   -     5.9
Flame length (ft)       1.9   2.5   3.5   0.5   2.2   3.0   2.2



FIRE EFFECTS ON TARGET SPECIES : 
Fire moss was apparently not present in the prefire community.  For the
first 2 years after fire, heavily burned sites were invaded by fire
moss, which dominated along with fireweed (Epilobium angustifolium) and
Marchantia polymorpha.  Fire moss greatly increased in biomass for the
first 3 postfire years from about 8 g/m sq in 1979 to 38 g/m sq in 1980
and almost 60 g/m sq in 1981.


FIRE MANAGEMENT IMPLICATIONS : 
Species such as fire moss tend to invade heavily burned areas by light,
wind-borne spores.  However, competition from sprouting plants on
lightly burned areas tends to limit fire moss invasion.  Areas must be
burned severely if a postfire community dominated by fire moss is the
goal.

Related categories for Species: Ceratodon purpureus | Fire Moss