ECOLOGY OF FIRE IN GRASSLANDS
249
Fire commonly Savors forbs over grasses in both annual grassland
(l%entley and Fenner, 1958; Biswell, 1956; Hervey, 1949) or perennial
grassland (Aikman, 1955; Aldous, 1934; Cushwa and Redd, 1966;
Hopkins et ul., 1948; Weaver and Rowland, 1952), but there are exceptions in which grasses are Savored at the expense of forbs, aa in Missouri
(Kucera and Kelling, 1964; Penfound and Kelting, 1950) and in the
Transvaal (Cook, 1965). In rather dry bteppe annuals may gain a t the
expense of perenniale in consequence of burning (Hopkins et al., 1948;
Pickford, 1932; Reynolds and Bohning, 1950; West, 1965).
From the Fctandpoint of palatability t,o animals of the species favored
by fire, burning may improve grasslands (Acocks, 1965; Aldous, 1934;
Cook, 1939) or reduce its value to livestock (Brynard, 19G5; Camp,
1932; Clarke et al., 1943; Staples, 1926). As discussed earlier the increase of legumes following fire on the coastal plain of southeastern
North America greatly increases quail food.
In apparently rare situations fire may have virtually no effect on the
composition of vegetation (Backlund, 1956), possibly in consequence
of a long history of natural selection under repeated burning. Elsewhere
it may alter the composition with many years being required for a
return to the pre-burn condition (Blaisdell, 1953; Lemon, 1949). In
North Dakota floristic differences between contiguous burned and unburned areas were observed to increase progressively for at least 4 years
after a fire (Dix, 1960).
Fire may enrich a flora when none of the species already on the
habitat are destroyed but the stand is opened up to allow opportunistic
species to invade (Lemon, 1949; Ramsay and Innes, 1963). Another
factor promoting floristic enrichment is the removal of heavy litter
which may accumulate in graasland, long unburned, and cause the
elimination of all but a few species which are able to complete their
life cycles despite the detrimental effect of litter on seedling establishment of most species (Heady, 1956; Weaver and Rowland, 1962).
When burning improves a single stand of grassland from the grazier’a
standpoint (i.e. increases productivity or nutritive value of herbage, or
damages woody plants), this often means only that favorable influences
outweigh the unfavorable (e.g. increased erosion). A t a higher level of
complexity this principle applies to the firing of an entire vegetation
mosaic, for the net effect in some specific community types may be
beneficial whereas other components of the landscape mosaic are degraded (Brynard, 1965; Clarke et al., 1943; Hopkins, eb al., 1948). Thus
if it is impractical to burn the stands separately, it is necessary to
consider the specific effects on the different communities aa well as the
relative amounts of those communities before recommending the use
of fire.
249
Fire commonly Savors forbs over grasses in both annual grassland
(l%entley and Fenner, 1958; Biswell, 1956; Hervey, 1949) or perennial
grassland (Aikman, 1955; Aldous, 1934; Cushwa and Redd, 1966;
Hopkins et ul., 1948; Weaver and Rowland, 1952), but there are exceptions in which grasses are Savored at the expense of forbs, aa in Missouri
(Kucera and Kelling, 1964; Penfound and Kelting, 1950) and in the
Transvaal (Cook, 1965). In rather dry bteppe annuals may gain a t the
expense of perenniale in consequence of burning (Hopkins et al., 1948;
Pickford, 1932; Reynolds and Bohning, 1950; West, 1965).
From the Fctandpoint of palatability t,o animals of the species favored
by fire, burning may improve grasslands (Acocks, 1965; Aldous, 1934;
Cook, 1939) or reduce its value to livestock (Brynard, 19G5; Camp,
1932; Clarke et al., 1943; Staples, 1926). As discussed earlier the increase of legumes following fire on the coastal plain of southeastern
North America greatly increases quail food.
In apparently rare situations fire may have virtually no effect on the
composition of vegetation (Backlund, 1956), possibly in consequence
of a long history of natural selection under repeated burning. Elsewhere
it may alter the composition with many years being required for a
return to the pre-burn condition (Blaisdell, 1953; Lemon, 1949). In
North Dakota floristic differences between contiguous burned and unburned areas were observed to increase progressively for at least 4 years
after a fire (Dix, 1960).
Fire may enrich a flora when none of the species already on the
habitat are destroyed but the stand is opened up to allow opportunistic
species to invade (Lemon, 1949; Ramsay and Innes, 1963). Another
factor promoting floristic enrichment is the removal of heavy litter
which may accumulate in graasland, long unburned, and cause the
elimination of all but a few species which are able to complete their
life cycles despite the detrimental effect of litter on seedling establishment of most species (Heady, 1956; Weaver and Rowland, 1962).
When burning improves a single stand of grassland from the grazier’a
standpoint (i.e. increases productivity or nutritive value of herbage, or
damages woody plants), this often means only that favorable influences
outweigh the unfavorable (e.g. increased erosion). A t a higher level of
complexity this principle applies to the firing of an entire vegetation
mosaic, for the net effect in some specific community types may be
beneficial whereas other components of the landscape mosaic are degraded (Brynard, 1965; Clarke et al., 1943; Hopkins, eb al., 1948). Thus
if it is impractical to burn the stands separately, it is necessary to
consider the specific effects on the different communities aa well as the
relative amounts of those communities before recommending the use
of fire.