EOOLOOY OF FIaE IN UtlASSLANDS
217
after ignition on the bottomland sits, but not until 3-4 min after on
the upland. On the south-facing dope temperatures in exoms of 100°C
p r s L t d for 145 am, w h e w on the bothmiand this level endured
167 set. The rate of temperature increese waa aJw&ys steeaejr than the
drop. Later, Iwanami and Iizumi (1966b) reoorded temperature 89 &h
as 877°C at an altitude of 5-11 om, when fire oonaumed a litter load of
1.2 kg/ma of ground surfaoe.
During the burning of a stand of annual grtwmi in Celifomia where
the soil surface maximum rose to 12loC, the temperetuFes at 25, 61,
76, and 100 mm rose t o 8’2,7P, 63, and 67°C (Bentley and Fanner, 1958).
Where the iitter cover waa heavier, temperature at the mil surface remained below 93°C. In another study of temperature profiles during
the firing of the aame general type of vegetation, maximum temperatures were always reached 1-20 cm above the soil, regardless of the
season of burning (McKell et aE., 1962). Elsewhere in California
(Lawrence, 1966), a maximum tempratwe of 288OC haR heen reported
“on R grassy surface” in an opening in chaparral. At a depth of 25 mm
the maximum soil temperature during one of them annual grass fires
was 82°C.
The drier the soil the higher its ~ 4 u r f m temperature when gram burns,
but at the same time the low moisture oontent reduces the downward
conduction of heat. Heyward (1938) ~tcltee that aa mbtm oontent
incwasee, heat conduction through a soil inarecLeee up to a point, than
remains oonstant, He found texture itself of little import.llacle,
In open pine forest with a hewy grass u n & m in southeatern
North America Heyward (1938) found iira d d o m raising the tems r s t u r e of the upper 3-6 mm layer of d l to 93OC, with the maximum
values usually persisting no longer than 2-4 min. At 12 mm deep t h a w
was uaually very little rise in temperature. Small bits of air-dry plant
material placed in the soil and heated artificially did not start to char
until temperatures rose to 204°C; t h w in this region it seems rather
certain that charcoal is not formed in plaoe below the soil surfme.
In Venezuelan savanna8 mil surface temperatures during gram fires
seldom rise above OOOC, but 121 “C was recorded in California as R stand
of annual grasses burned (Bentley and Fenner, 1958). Even where the
fuel w m heavy, Roil temper&ures during a gram fire in New South
Wales, Australia, rose to only 76-5OC (starting from 13°C) at a depth
of 1 mm, and at a depth of 15 mm the temperatwe was raised by only
10°C (Norton and McGarity, 1966).
A t the b a ~ e of a burning paw tussock in southern Africa temperatuns exceeded 600°C ae B fire swept over the veld, yet tempmtum at
a depth of 5 m m in the soil roee very little (Cook, 1939). The high s w -
face temperature there persisted about 0 min. As a heavy etand of grms
217
after ignition on the bottomland sits, but not until 3-4 min after on
the upland. On the south-facing dope temperatures in exoms of 100°C
p r s L t d for 145 am, w h e w on the bothmiand this level endured
167 set. The rate of temperature increese waa aJw&ys steeaejr than the
drop. Later, Iwanami and Iizumi (1966b) reoorded temperature 89 &h
as 877°C at an altitude of 5-11 om, when fire oonaumed a litter load of
1.2 kg/ma of ground surfaoe.
During the burning of a stand of annual grtwmi in Celifomia where
the soil surface maximum rose to 12loC, the temperetuFes at 25, 61,
76, and 100 mm rose t o 8’2,7P, 63, and 67°C (Bentley and Fanner, 1958).
Where the iitter cover waa heavier, temperature at the mil surface remained below 93°C. In another study of temperature profiles during
the firing of the aame general type of vegetation, maximum temperatures were always reached 1-20 cm above the soil, regardless of the
season of burning (McKell et aE., 1962). Elsewhere in California
(Lawrence, 1966), a maximum tempratwe of 288OC haR heen reported
“on R grassy surface” in an opening in chaparral. At a depth of 25 mm
the maximum soil temperature during one of them annual grass fires
was 82°C.
The drier the soil the higher its ~ 4 u r f m temperature when gram burns,
but at the same time the low moisture oontent reduces the downward
conduction of heat. Heyward (1938) ~tcltee that aa mbtm oontent
incwasee, heat conduction through a soil inarecLeee up to a point, than
remains oonstant, He found texture itself of little import.llacle,
In open pine forest with a hewy grass u n & m in southeatern
North America Heyward (1938) found iira d d o m raising the tems r s t u r e of the upper 3-6 mm layer of d l to 93OC, with the maximum
values usually persisting no longer than 2-4 min. At 12 mm deep t h a w
was uaually very little rise in temperature. Small bits of air-dry plant
material placed in the soil and heated artificially did not start to char
until temperatures rose to 204°C; t h w in this region it seems rather
certain that charcoal is not formed in plaoe below the soil surfme.
In Venezuelan savanna8 mil surface temperatures during gram fires
seldom rise above OOOC, but 121 “C was recorded in California as R stand
of annual grasses burned (Bentley and Fenner, 1958). Even where the
fuel w m heavy, Roil temper&ures during a gram fire in New South
Wales, Australia, rose to only 76-5OC (starting from 13°C) at a depth
of 1 mm, and at a depth of 15 mm the temperatwe was raised by only
10°C (Norton and McGarity, 1966).
A t the b a ~ e of a burning paw tussock in southern Africa temperatuns exceeded 600°C ae B fire swept over the veld, yet tempmtum at
a depth of 5 m m in the soil roee very little (Cook, 1939). The high s w -
face temperature there persisted about 0 min. As a heavy etand of grms