ECOLOGY OF FIRE IX GRASSLANDS
253
In Africa, burning increases production in relatively moist regions
but is generally detrimental in more arid regions (Staples, 1945; Weat,
1965). The tame relation was shown to hold in the climatic transect
across the mid-continental graesland of North America. Kucera arid
Ehrenreich (1962) suggest that the increaaed production consequent on
burning in only the wetter margin of steppe may simply reflect release
from a greater depressing effect of heavier litter accumulations in this
climate. Their hypothesis would be adequate if fire had little or no
effect on production in the West while increasing it eastward, but the
usual depression of production in drier regions shows that more is
involved than the removal of the suppressing effect of litter. For reasons
not wholly clear burning in the moist easterly region does not injure
plants, but instead removes some adverse (cooling?) effect of litter. In
the dry western part of the mid-continental steppe, the litter cover
would seem too scant to produce adverse shading, and in fact might be
useful to shield against excess insolation. The type of plant or the condition of vegetation during the fire semon, may also be involved in this
injury by fire in the West. Certainly more is involved than just low
rainfall, for still farther west, between the Rockies and the Cascades,
where climates are fully as dry, but the seaaonal distribution of precipitation is much different, stimulation rather than injury is again
the rule.
In southern Africa regular burning is necessary in order to maintain
the best quality of forage and to keep the desirable Themeda triandru
dominant, these effects being so desirable that some loss of productivity
can be sacrificed (Botha, 1946; Cook, 1939).
Burning savanna grasses (chry80pogm fallax, Sorghum plumosum,
Thmeda awtralis) in northern Australia reduces their productivity, the
later the burn in the wet season the greater the reduction (Smith, 1960).
When Nolinia cuerulea communities in Britain are burned, productivity is either unchanged or reduced, the latter being associated
with soils that are better drained (Grant et aE., 1963).
Although grassland fires in the Arctic prolong the season of foliar
activity, total dry-matter production in the first post-burn seaaon is
reduced (Fridriksson, 1963).
January fire in Trachypogm savanna in Venezuela reduced shoot
production by about a third in the first post-burn aeaaon (Blydenstein,
1963). Burning in March reduced it slightly, but burning in November
or December, which is the start of the dry seaaon, resulted in an increase
of about BOY,.
It is important in evaluating the effects of grassland fires on total
productivity of the plant community to take into account concomitant
changes in the character of the plants. For example, a net increase may
253
In Africa, burning increases production in relatively moist regions
but is generally detrimental in more arid regions (Staples, 1945; Weat,
1965). The tame relation was shown to hold in the climatic transect
across the mid-continental graesland of North America. Kucera arid
Ehrenreich (1962) suggest that the increaaed production consequent on
burning in only the wetter margin of steppe may simply reflect release
from a greater depressing effect of heavier litter accumulations in this
climate. Their hypothesis would be adequate if fire had little or no
effect on production in the West while increasing it eastward, but the
usual depression of production in drier regions shows that more is
involved than the removal of the suppressing effect of litter. For reasons
not wholly clear burning in the moist easterly region does not injure
plants, but instead removes some adverse (cooling?) effect of litter. In
the dry western part of the mid-continental steppe, the litter cover
would seem too scant to produce adverse shading, and in fact might be
useful to shield against excess insolation. The type of plant or the condition of vegetation during the fire semon, may also be involved in this
injury by fire in the West. Certainly more is involved than just low
rainfall, for still farther west, between the Rockies and the Cascades,
where climates are fully as dry, but the seaaonal distribution of precipitation is much different, stimulation rather than injury is again
the rule.
In southern Africa regular burning is necessary in order to maintain
the best quality of forage and to keep the desirable Themeda triandru
dominant, these effects being so desirable that some loss of productivity
can be sacrificed (Botha, 1946; Cook, 1939).
Burning savanna grasses (chry80pogm fallax, Sorghum plumosum,
Thmeda awtralis) in northern Australia reduces their productivity, the
later the burn in the wet season the greater the reduction (Smith, 1960).
When Nolinia cuerulea communities in Britain are burned, productivity is either unchanged or reduced, the latter being associated
with soils that are better drained (Grant et aE., 1963).
Although grassland fires in the Arctic prolong the season of foliar
activity, total dry-matter production in the first post-burn seaaon is
reduced (Fridriksson, 1963).
January fire in Trachypogm savanna in Venezuela reduced shoot
production by about a third in the first post-burn aeaaon (Blydenstein,
1963). Burning in March reduced it slightly, but burning in November
or December, which is the start of the dry seaaon, resulted in an increase
of about BOY,.
It is important in evaluating the effects of grassland fires on total
productivity of the plant community to take into account concomitant
changes in the character of the plants. For example, a net increase may