FIRE CASE STUDIES
SPECIES: Chamaecyparis nootkatensis | Alaska-Cedar 



CASE NAME : 
Fuel properties and slash-burning-induced nutrient losses


REFERENCE : 
Feller, M. C. 1988 [13]

SEASON/SEVERITY CLASSIFICATION : 
The plots were burned on 10 different days in July, August, and
September 1984 to incorporate a range of fuel moisture conditions.


STUDY LOCATION : 
The prescribed fire took place on a clearcut area of the University of
British Columbia's Research forest which is located appoximately 24
miles (40 km) east of Vancouver, British Columbia.  The cordinates are
49 degrees 17 minutes N latitude, 122 degrees 35 minutes W longitude.


PREFIRE VEGETATIVE COMMUNITY : 
The preburn community was a productive coastal western hemlock forest
composed of western hemlock (Tsuga heterophylla), western redcedar
(Thuja plicata), Alaska-cedar (Chamaecyparis nootkatensis), and
Douglas-fir (Pseudotsuga menziesii) that had been clearcut.


TARGET SPECIES PHENOLOGICAL STATE : 
NO-ENTRY


SITE DESCRIPTION : 
The study site was on a gentle, easterly slope at an elevation of 500 m
(1,650 ft).  The climate of the area is marine, warm-temperate, rainy.
The mean annual precipitation is from 87 to 138 inches (220-350 cm),
which is received mainly in the form of rain.  The soil over most of the
area was a Typic Haplorthod with a mor forest floor with a mean depth of
10 inches (26 cm).

The area had been logged during a snow-free period using a high lead
harvesting system.  After clearcutting the slash was sorted by species*
into five diameter classes:

                (1)  < 1 cm
                (2)  1.1-3.0 cm
                (3)  3.1-5.0 cm
                (4)  5.1-7.0 cm
                (5)  > 7 cm

*Alaska-cedar and western redcedar were combined and shall be henceforth
referred to as cedar.

The area was then divided into 50 2.25-square-meter plots that were
greater than 0.5 meter apart.  These were slpit into 10 groups of 5
plots; within each group the plots were randomly assigned a species.
Western hemlock slash had three fuel loadings (4.4, 9.9, 17.7 kg/m2)
while cedar and Douglas-fir had one fuel loading (9.9 kg/m2).  Each plot
received all size classes of slash.  Ten samples of slash were oven
dried and used to determine prefire chemical and percent composition.


FIRE DESCRIPTION : 
The fire was ignited on each plot using a strip of gasoline around the
perimeter of the plot.  The five plots within a group were ignited
separatly, but within minutes of each other.

Atmospheric conditions and fuel moisture at the time of ignition of each
fire were as follows:

                Temp.   Relative        Wind speed      Fine fuel
                 C      Humidity        (km/hr)         moisture (%)

July    17      23.8    68              7               15                
        23      27.7    37              5               14
        26      21.4    59              6               20
        30      25.1    59              7               15

August   2      20.5    64              7               18
        13      14.8    82              4               19
        16      25.1    52              3               13
        22      22.4    58              7               15

Sept.   14      22.2    49              5               32
        26      15.3    64              4               20 

Depth of burn into the forest floor (L, F, H layers combined) averaged
1.9 cm on the cedar plots, 1.6 cm on Douglas fir plots, and 1.8 on the
western hemlock.  The total mean slash consumption per species in
kilograms per square meter was 4.2, 3.3, and 3.6 for cedar, Douglas-fir,
and western hemlock, respectively.


FIRE EFFECTS ON TARGET SPECIES : 
Cedar slash had the greatest depth of burn, which in turn ment greater
losses of nutrients to the atmosphere.  The mean nutrient loss (grams
per square meter) for seven elements from the three types of slash were
as follows:

                N       P       S       K       Na      Mg      Ca

Cedar           26.3    1.3     2.7     3.7     0.1     2.0     19.5
Douglas-fir     19.5    1.2     2.2     2.3     0.1     1.1     11.0
Western hemlock 20.9    0.2     2.3     1.0     0.1     0.9      3.8


FIRE MANAGEMENT IMPLICATIONS : 
This study revealed that western hemlock/western redcedar/Alaska-cedar
forests produce greater nutrient losses to the atmosphere when the slash
composition has a greater proportion of Alaska-cedar and western
redcedar.  One can expect smaller nutrient losses when western hemlock
makes up the majority of the slash.

Nutrient losses can be limited if the the forest floor and larger fuels
are moist when burned.  This limits fuel consumption.  Also nutrient
loss can be reduced by more complete utilization during harvest, thus
reducing the slash load.

Related categories for Species: Chamaecyparis nootkatensis | Alaska-Cedar