2 51
It. DAtTBEXV31E
gracilis is dominrtnt, fire brought nbout a great reduction of production
in the first post-burn 8etmon (Hopkius et a,!., 1948; Launchbaugh, 1964).
In this area fall burning is far more detrihtental to subsequent production than is spring burning (Hopkins et 4 , , 1948).
In somewhat similar Boutelan gracilis steppe in South Dakota, fire
reduced dry-matter production (Lsrson and Whitman, 1942), and in
North Dakota production quantity was reduced by a single burn with
recovery not yet completed 4 years later (Dix, 1960). Farther north in
Alberta, but in the same steppe belt, production was down about 50%
the first season following a spring fire, still 15% below normal the
second, with recovery complete by the third (Clarke et al., 1943). Fall
burning here was less deleterious, reducing production by only 30%
with recovery complete by the second post-burn season.
In the southern Rockies where steppes are dominated by several
species of Boutelowl including B. g r a ~ i h ,
production was reduced the
first post-burn season but normal thereafter (Reynolds and Bohning,
1956).
Early work in the Artemisia tridentdo shrub-steppe in western Colorado showed that a fire which eliminate4 ,‘I>> fire-sensitive Artemi8ia
increased grass production by 155% the nt.:.t summer, with the increase
rising to 336:/, during the second (Hanson, 1929). Later work by Blaisdell (1953) and Pechanec et al. (1954) confirmed this effect in eastern
Idaho, with production here increasing prltgressively up to the third
or fourth post-burn season after which there was n very gradual decline
with over half the gain bcing lost hy the fifteenth year. Gradual reinvasion by the ArfPmisia during this time w&9 too small to account for
the reduction in grass prodnctivity. It was noted here that on a habitat
type where Artcmisia tripartita was the dominant shrub the post-burn
increase in productivity was much Iess. In contrast with the above,
Mueggler and Blaisdell (1958) followed still another fire in Artemisia
Iridentata shrub-steppe in eaatern Idaho and found production lowered
during the first 2 post-hum seasons, returning to normal the third.
Over much of southern Idaho a combination of fire that eliminated
Artemisia tridentafa, and overgrazing t h a t eliminated perennial grasses,
has left the land occupied chiefly by the alien Bromus tectorum. Burning
stands of this grass lowers production in the first post-burn seaon,
especially if the fire occurs early in the dry season before the spikelets
shatter and the florets have had time to work their way through the
litter to the soil surface, 90 that population density is subsequently reduced (Pechanec and Hull, 1946). Fire running through a comparable
stand of exotic grasses near Berkeley, California, reduced production on
two of four sites analysed, with no change measurable on the others
(Hervey, 1949).
It. DAtTBEXV31E
gracilis is dominrtnt, fire brought nbout a great reduction of production
in the first post-burn 8etmon (Hopkius et a,!., 1948; Launchbaugh, 1964).
In this area fall burning is far more detrihtental to subsequent production than is spring burning (Hopkins et 4 , , 1948).
In somewhat similar Boutelan gracilis steppe in South Dakota, fire
reduced dry-matter production (Lsrson and Whitman, 1942), and in
North Dakota production quantity was reduced by a single burn with
recovery not yet completed 4 years later (Dix, 1960). Farther north in
Alberta, but in the same steppe belt, production was down about 50%
the first season following a spring fire, still 15% below normal the
second, with recovery complete by the third (Clarke et al., 1943). Fall
burning here was less deleterious, reducing production by only 30%
with recovery complete by the second post-burn season.
In the southern Rockies where steppes are dominated by several
species of Boutelowl including B. g r a ~ i h ,
production was reduced the
first post-burn season but normal thereafter (Reynolds and Bohning,
1956).
Early work in the Artemisia tridentdo shrub-steppe in western Colorado showed that a fire which eliminate4 ,‘I>> fire-sensitive Artemi8ia
increased grass production by 155% the nt.:.t summer, with the increase
rising to 336:/, during the second (Hanson, 1929). Later work by Blaisdell (1953) and Pechanec et al. (1954) confirmed this effect in eastern
Idaho, with production here increasing prltgressively up to the third
or fourth post-burn season after which there was n very gradual decline
with over half the gain bcing lost hy the fifteenth year. Gradual reinvasion by the ArfPmisia during this time w&9 too small to account for
the reduction in grass prodnctivity. It was noted here that on a habitat
type where Artcmisia tripartita was the dominant shrub the post-burn
increase in productivity was much Iess. In contrast with the above,
Mueggler and Blaisdell (1958) followed still another fire in Artemisia
Iridentata shrub-steppe in eaatern Idaho and found production lowered
during the first 2 post-hum seasons, returning to normal the third.
Over much of southern Idaho a combination of fire that eliminated
Artemisia tridentafa, and overgrazing t h a t eliminated perennial grasses,
has left the land occupied chiefly by the alien Bromus tectorum. Burning
stands of this grass lowers production in the first post-burn seaon,
especially if the fire occurs early in the dry season before the spikelets
shatter and the florets have had time to work their way through the
litter to the soil surface, 90 that population density is subsequently reduced (Pechanec and Hull, 1946). Fire running through a comparable
stand of exotic grasses near Berkeley, California, reduced production on
two of four sites analysed, with no change measurable on the others
(Hervey, 1949).