254
R. DAUBENMIRE
be a result of great stimulation of inflorescence development whioh
more than offseta a reduction in the number of vegetative tillers
(Ehrenreich and Aikman, 1963). Also, fire may increase basal area
without having much effect on production (Hopkins et al., 1948).
While burning increases production in many grassland areas, the
gains in forage that the grazier anticipa,tes tend to be offset by other
considerations. Often grazing must be reduced in advance of burning
to allow sufficient litter to accumulate to carry fie. I n dry steppes a
second loss is represented by the standing, naturally dried grass that is
consumed. Thirdly, grazing must be held in abeyance for a time after
the fire to prevent excessive use which would lead to damage of the
plants. Fire becomes economical as a means of increasing productivity
only if the gain through increased yield exceeds the sum of these losaea.
VII. TIME RELATIONS
Throughout this review sufficient reference has been made to the
significance of the time factor to warrant the conclusion that in nearly
every influence of burning, the time of the year, or even the time of day,
when the fire occurs is almost as important as the occurrence of the
fire itself. Complete reversals of the type of influence may result simply
from differences in timing.
In comparing the effects of intentional and natural burns it is important to note that natural burns have their highest frequency during
the driest part of the year, where@ planned burning is often done
deliberately at other seasons as a means of maximizing desirable fire
influences (Komarek, 1965).
VIII. BURNING VERSUS MOWING
Mowing grassland, followed by removal of the cut material, often
accomplishes most of the conspicuous changes wrought by fire, and
therefore is of significance in experimental work aimed at understanding the ecology of fire in grasslands. Some of the results of comparisons
of mowing versus burning on different parts of the eame stands of grassland vegetation will now be reviewed.
At Escourt in Natal, southeastern Africa, annual mowing maintained
grassland in much the same condition as annual burning (Scott, 1951,
see West, 1965), but at Tabamhlope where rainfall is higher, mowing is
preferred as a management technique’since it results in a superior
quality and quantity of forage, promotes better infiltration and penetration of water into the soil, and causes plant# to suffer leas from drought
(Scott, 1951; West, 1949, see West, 1965). In Transvaal it w&8 found
that cutting and burning have similar influences in raising the rnohture,
R. DAUBENMIRE
be a result of great stimulation of inflorescence development whioh
more than offseta a reduction in the number of vegetative tillers
(Ehrenreich and Aikman, 1963). Also, fire may increase basal area
without having much effect on production (Hopkins et al., 1948).
While burning increases production in many grassland areas, the
gains in forage that the grazier anticipa,tes tend to be offset by other
considerations. Often grazing must be reduced in advance of burning
to allow sufficient litter to accumulate to carry fie. I n dry steppes a
second loss is represented by the standing, naturally dried grass that is
consumed. Thirdly, grazing must be held in abeyance for a time after
the fire to prevent excessive use which would lead to damage of the
plants. Fire becomes economical as a means of increasing productivity
only if the gain through increased yield exceeds the sum of these losaea.
VII. TIME RELATIONS
Throughout this review sufficient reference has been made to the
significance of the time factor to warrant the conclusion that in nearly
every influence of burning, the time of the year, or even the time of day,
when the fire occurs is almost as important as the occurrence of the
fire itself. Complete reversals of the type of influence may result simply
from differences in timing.
In comparing the effects of intentional and natural burns it is important to note that natural burns have their highest frequency during
the driest part of the year, where@ planned burning is often done
deliberately at other seasons as a means of maximizing desirable fire
influences (Komarek, 1965).
VIII. BURNING VERSUS MOWING
Mowing grassland, followed by removal of the cut material, often
accomplishes most of the conspicuous changes wrought by fire, and
therefore is of significance in experimental work aimed at understanding the ecology of fire in grasslands. Some of the results of comparisons
of mowing versus burning on different parts of the eame stands of grassland vegetation will now be reviewed.
At Escourt in Natal, southeastern Africa, annual mowing maintained
grassland in much the same condition as annual burning (Scott, 1951,
see West, 1965), but at Tabamhlope where rainfall is higher, mowing is
preferred as a management technique’since it results in a superior
quality and quantity of forage, promotes better infiltration and penetration of water into the soil, and causes plant# to suffer leas from drought
(Scott, 1951; West, 1949, see West, 1965). In Transvaal it w&8 found
that cutting and burning have similar influences in raising the rnohture,