ECOLOQY OF FIRE I N GRASSLANDS
223
drier and windy Artemiaia steppe of eastern Idaho wind erosion of
Randy loams is proportional to the intensity of the fire, although soil
blowing is arrested after the second post-burn season (Blaidell, 1953)
and could not be detected on loams even in the fimt post-burn seaaon.
In Kenya, regular burning of the grass does not cause erosion
(Edwards, 1942), and this seems to be generally true in tropical savanna
(Nye and Greenland, 1960), but in subtropical Queensland erosion is
accelerated by grass fires (Shaw, 1957).
The burning of shrub savanna in the Union of South Africa was
observed' to increbe the rate of storm-flow at its peak, but it did not
change the volume of storm-flow or total annual discharge (Rycroft,
1947). Despite the increased rate of run-off in this region in the first
year after a grass fire, there is no significant eroeional loss unless the
land is subject to grazing (Banks, 1964; Cook, 1939). However, in the
drier parts of southern Africa annual burning promotes erosion as well
as accelerated run-off, the effecta being evident even on rather flat
land, becoming catastrophic on steep slopes (Du Pleasis and Mostert,
1965; West, 1965).
Fire sweeping through Danthonia jlavescena grassland in the mountains of New Zealand generally triggers an abrupt and devastating
erosion of the slopes (Various Authom, 1954; Barker, 1953). A severe
fire there, reduced loaf length of the caespitose Chionochloa rigida, and
normal coverage by the plants was not restored for some 3-4 years.
This change seemed critical with regard to the initiation of soil erosion
(O'Connor and Powell, 1963).
After 5 years of annual burning of Heteropogon contortus grassland in
Queensland, Australia, the increased amount of bare ground produced
so much erosion that the grass bunches had become pedestalled (Shaw,
1957).
Since the burning of a dormant grass cover leaves the soil bare and
subject to erosion until a new plant cover forms, there is widespread
opinion that wbere burning is a desirable management practice, this
should be done as late in the dormant season as feasible to minimize
the period when the soil lies bare (L. Cook, 1965). However, this involves the hazard of accidental fires during the driest season when
damago would be maximum.
D. SOIL MOISTURE
Some of the changes induced by burning grassland tend to reduce
soil moisture, whereas others favor an increase. In early spring the
relatively high soil temperatures on a burn lower water viscosity and,
in turn, speed up percolation and lower the field capacity. These influences, coupled with increased evaporation from the warmed surface,
223
drier and windy Artemiaia steppe of eastern Idaho wind erosion of
Randy loams is proportional to the intensity of the fire, although soil
blowing is arrested after the second post-burn season (Blaidell, 1953)
and could not be detected on loams even in the fimt post-burn seaaon.
In Kenya, regular burning of the grass does not cause erosion
(Edwards, 1942), and this seems to be generally true in tropical savanna
(Nye and Greenland, 1960), but in subtropical Queensland erosion is
accelerated by grass fires (Shaw, 1957).
The burning of shrub savanna in the Union of South Africa was
observed' to increbe the rate of storm-flow at its peak, but it did not
change the volume of storm-flow or total annual discharge (Rycroft,
1947). Despite the increased rate of run-off in this region in the first
year after a grass fire, there is no significant eroeional loss unless the
land is subject to grazing (Banks, 1964; Cook, 1939). However, in the
drier parts of southern Africa annual burning promotes erosion as well
as accelerated run-off, the effecta being evident even on rather flat
land, becoming catastrophic on steep slopes (Du Pleasis and Mostert,
1965; West, 1965).
Fire sweeping through Danthonia jlavescena grassland in the mountains of New Zealand generally triggers an abrupt and devastating
erosion of the slopes (Various Authom, 1954; Barker, 1953). A severe
fire there, reduced loaf length of the caespitose Chionochloa rigida, and
normal coverage by the plants was not restored for some 3-4 years.
This change seemed critical with regard to the initiation of soil erosion
(O'Connor and Powell, 1963).
After 5 years of annual burning of Heteropogon contortus grassland in
Queensland, Australia, the increased amount of bare ground produced
so much erosion that the grass bunches had become pedestalled (Shaw,
1957).
Since the burning of a dormant grass cover leaves the soil bare and
subject to erosion until a new plant cover forms, there is widespread
opinion that wbere burning is a desirable management practice, this
should be done as late in the dormant season as feasible to minimize
the period when the soil lies bare (L. Cook, 1965). However, this involves the hazard of accidental fires during the driest season when
damago would be maximum.
D. SOIL MOISTURE
Some of the changes induced by burning grassland tend to reduce
soil moisture, whereas others favor an increase. In early spring the
relatively high soil temperatures on a burn lower water viscosity and,
in turn, speed up percolation and lower the field capacity. These influences, coupled with increased evaporation from the warmed surface,