FIRE CASE STUDIES
SPECIES: Chrysolepis chrysophylla | Giant Chinquapin 



CASE NAME : 
Pringle Falls, Oregon - preharvest underburn



SEASON/SEVERITY CLASSIFICATION : 
Initial burn:  upper plot - September 27, 1976/moderate
Initial burn:  lower plot - October 1, 1976/ moderate
Reburn:  upper plot - October 2, 1979/moderate
Reburn:  lower plot - June 9, 1980/low


STUDY LOCATION : 
The study was conducted on the east slope of Lookout Mountain in the
Pringle Falls Experimental Forest, approximately 30 miles (48 km)
south-southwest of Bend, Oregon.


PREFIRE VEGETATIVE COMMUNITY : 
Two distinct units were burned.  The lower unit is representative of the
ponderosa pine (Pinus ponderosa)/bitterbrush (Purshia
tridentata)-snowbrush (Ceanothus velutinus)/needlegrass (Stipa spp.)
habitat-community type as described by Volland [76].  The upper unit is
identified as a mixed conifer-ceanothus-sedge (Carex spp.) community
type.  Ponderosa pine was the most common overstory species with basal
area ranging from 100 to 140 square feet per acre (23-32 sq m/ha).  Some
white fir (Abies concolor) saplings and seedlings were also present on
the upper plot.  Common shrubs included snowbrush ceanothus, giant
chinquapin, bitterbrush, and greenleaf manzanita (Arctostaphylos
patula).  Needlegrass and sedges were also present.


TARGET SPECIES PHENOLOGICAL STATE : 
Presumed dormant for both burns.


SITE DESCRIPTION : 
Elevation:  upper plot -   5,000 feet (1,525 m)
            lower plot - 4,550 feet (1,390 m)
Annual precipitation:  30 inches (76 cm), mostly in the form of snow.
Aspect:  east


FIRE DESCRIPTION : 
The burn site received 1.5 inches (3.8 cm) of precipitation a week
before the initial burn.  The first prescribed fire was a moderate burn
designed to reduce flash fuel loadings and create a verticle separation
of fuels.  Consequently, fuel consumption was low.  The reburn took
place 3 years later during a dry fall and was conducted under low duff
moisture conditions.  Approximately 70 percent of the litter and duff,
and 57 percent of the 1000-hour fuels were consumed during the second
burn.

Fuel and weather conditions during both burns is presented below:

                          Initial burn           Reburn

Burn date              September 27, 1976     October 2, 1979
Weather Degrees F          56 - 71              56 - 67
       (Degrees C)        (13 - 22)            (13 - 19)
Relative humidity %        37 - 61              38 - 54
Wind mph                    0 - 8                0 - 5
     (km/hr)              (0 - 13)              (0 - 8)
Fuel moisture content % 
     new litter            12 - 15               7 - 20
     old litter            10 - 30              11 - 20
     duff                  26 - 65              14 - 21
     1 hr TL* 1              ---                11 - 13
     10 hr TL dead           ---                11 - 13
     100 hr TL dead          ---                  12
     1000 hr TL dead         ---                13 - 23
     0 - 1/4 inch dia.       ---                75 - 114
           live 
     1/4 - 1 inch dia.       ---                   75
           live 
     Shrub foliage           ---                95 - 129

*  Timelag fuel classes are used to indicate the time for a fuel
theoretically to lose 63.2 percent of its original moisture.  Diameter
size class ranges for each timlag class are listed below:

        Diameter (cm)          (in)        Timelag class (hrs)
         0 - 0.76            0 - 0.25           1
         0.76 - 2.53         0.25 - 1.0         10
        2.53 - 7.63          1.0 - 3.0          100
        7.63 - 20.32         3.0 - 8.0          1000

      
Burns produced the following fuel consumption:

                        Before          Before        After
                     initial burn       reburn       reburn
                         tons/acre  (tonnes/hectare)

Litter and duff      13.4 (30.0)      14.6 (32.6)   4.4 (9.8)
Time lag class (hrs)
        1             1.7 (3.7)        0.4 (1.0)    0.6 (1.3)
       10                ---              ---         ---
       100               ---           2.8 (6.2)    3.0 (6.8)
      1000               ---           7.4 (16.6)   3.2 (7.2)  


FIRE EFFECTS ON TARGET SPECIES : 
All four understory giant chinquapin were top-killed by the initial,
low-severity underburn and all sprouted.  Following the second
underburn, 50 percent of giant chinquapins died, and the sprouting
potential of surviving plants was severely reduced.  Resprouted plants
dominated areas from 16 to 26 feet (5-8 m) in diameter prior to the
reburn; afterwards surviving giant chinquapins produced only two or
three sprouts per plant, each occupying a site approximately 10 inches
(1/4 m) in diameter.


FIRE MANAGEMENT IMPLICATIONS : 
Giant chinquapin can be effectively controlled by preharvest
underburning when it occurrs on mixed-evergreen sites in central Oregon.
Although plants usually survive light underburns, plant mortality is
increased following high duff consumption reburns.  Sprouting vigor of
surviving giant chinquapins is greatly reduced.

Related categories for Species: Chrysolepis chrysophylla | Giant Chinquapin