FIRE CASE STUDIES
SPECIES: Pinus taeda | Loblolly Pine 



CASE NAME : 
Hardwood control and seedbed preparation in Georgia


REFERENCE : 
Brender, E. V.; Cooper, R. W. 1968 [8]


SEASON/SEVERITY CLASSIFICATION : 
Summer strip head fire/low- to moderate-severity
Summer backfire/low-severity
Winter strip head fire/low- to moderate-severity
Winter backfire/low-severity


STUDY LOCATION : 
The study was conducted in the Hitchiti Experimental Forest near Macon,
Georgia, in the rolling hills of the lower Piedmont.


PREFIRE VEGETATIVE COMMUNITY : 
The overstory consisted of 100 square feet basal area per acre (23 sq
m/ha) of 40-year-old loblolly pine (Pinus taeda).  Small understory
hardwoods included flowering dogwood (Cornus florida), sweetgum
(Liquidambar styraciflua), blackgum (Nyssa sylvatica), hawthorn
(Crataegus spp.), oak (Quercus spp.), hickory (Carya spp.), and winged
elm (Ulmus alata).  There were 750 small hardwoods per acre (1,850/ha)
from 0.6 to 6.5 inches (1.5-16.5 cm) in diameter and approximately 5,000
smaller stems per acre (12,000/ha).  Hardwoods made up 22 square feet
basal area per acre (5 sq m/ha).


TARGET SPECIES PHENOLOGICAL STATE : 
NO-ENTRY


SITE DESCRIPTION : 
The terrain was gently rolling with 10 to 20 percent slope.  Litter
accumulation was 4 to 8 tons per acre (9-18 metric tons/ha) of which
approximately 10 to 45 percent was hardwood litter.  The humus type was
shallow duff-mull.


FIRE DESCRIPTION : 
Twenty plots of 1.5 acres (0.6 ha) each were randomly assigned to 5
different treatments:  summer backfire, summer strip head fire, winter
backfire, winter strip head fire, and no fire.  Backfires were run down
slope and head fires up slope.  A complete stand inventory by species
and 1 inch (2.5 cm) diameter classes, a tally of stems less than 0.6
inches (1.5 cm) on 15 milacre quadrants, and litter fuel weights and
moisture were taken before and after the fire.  The following
fire-weather measurements were taken:  wind direction and speed, air
temperature, relative humidity, rate of flame spread, flame length,
depth of fire front, and time-temperature relationships at 1- and 4-foot
(0.3-1.2 m) heights.  Soil erosion and seedling regeneration in milacre
quadrants were evaluated after the fire.  Each plot was further
subdivided for repeat fires.  The repeat fire data will not be discussed
here because of difficulties and inconsistencies encountered with the
fires.

The following tables present fire data:

fire            rate of spread   litter consumption   energy release
                   ft/min             percent          Btu/min/ft

winter back          1.4                 38              1232
summer back          1.2                 46              1200
winter strip         8.8                 40              8448
summer strip        10.0                 53             11200

fire                temperature       duration
                      deg. C            

winter strip-1 ft      255            24 seconds above 200 degrees
winter strip-4 ft      130            43 seconds above 100 degrees
summer strip-1 ft      480            22 seconds above 400 degrees
summer strip-4 ft      220            27 seconds above 200 degrees



FIRE EFFECTS ON TARGET SPECIES : 
Summer fires top-killed more hardwoods than winter fires.  The following
table shows the percentage of hardwoods top-killed by summer and winter
fires:

d.b.h. class    summer kill    winter kill
  inches          percent        percent

     1              96             73
     2              64             73
     3              33             12
     4              18              7
     5              15              8
     6              13              0

There was no significant difference in percent hardwoods top-killed
between backfires and strip head fires.

Fuel consumption was greater in the summer than in the winter.

Seedlings were more abundant and better distributed on burned plots than
unburned plots.  Seedlings were also more abundant on plots burned in
the summer than in the winter.  The percent milacre stocking of
seedlings was 57 percent on the control, 77 percent on the winter fire
plots, and 90 percent on the summer fire plots.

Soil erosion was minimal, and no difference was found between season or
method of burning.


FIRE MANAGEMENT IMPLICATIONS : 
A single strip fire in the summer is the best method for removing
hardwoods and preparing an adequate seedbed.  Although there were no
significant differences between head strip fires and backfires, head
strip fires were cheaper and easier to control.  A summer strip fire
should only be conducted, however, if fuel accumulation is less than 10
tons per acre (22 metric tons/ha).  Optimum summer fire conditions were
a litter moisture content of 10 to 20 percent, a relative humidity of 20
to 60 percent, and a steady wind speed of 1 to 5 miles per hour (1.6-8
km/h).

Related categories for Species: Pinus taeda | Loblolly Pine