• IMMEDIATE FIRE EFFECT ON PLANT
• DISCUSSION AND QUALIFICATION OF FIRE EFFECT
• PLANT RESPONSE TO FIRE
• DISCUSSION AND QUALIFICATION OF PLANT RESPONSE
• FIRE MANAGEMENT CONSIDERATIONS

IMMEDIATE FIRE EFFECT ON PLANT:

Western wheatgrass is generally unharmed by fire. Smith and Busby [134] report that it is "slightly damaged" by fire in Wyoming. Rhizomes may be damaged but are generally not killed by fire.

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

No entry

PLANT RESPONSE TO FIRE:

Western wheatgrass cover usually increases or changes little after fire. On sagebrush (Artemisia spp.)-grass ranges western wheatgrass often revegetates rapidly after fire [152]. Recovery occurs within 2 to 5 years in sagebrush and pinyon-juniper zones of the Intermountain region [147,148,161]. In Nevada, western wheatgrass increased in frequency after fire; above ground biomass increased more than 7 times above preburn levels during the 1st postfire season [28]. In sagebrush (Artemisia spp.) communities of Wyoming, western wheatgrass generally increases after fire [133]. In eastern Montana, western wheatgrass production was unaffected by spring or fall burns [75]. In some instances, vegetative spread of western wheatgrass is enhanced by fire [158].

Fall burns can also stimulate productivity of western wheatgrass, but sometimes to a lesser degree than can spring burns [162,163]. In Montana, plants burned in fall and spring exhibited similar yields after mid-May [163]. Studies in eastern Montana indicate that western wheatgrass increases in abundance after spring, summer, and early fall burns. However, best response was noted after late summer or early fall fires [75].

Summer burns generally produce increases in western wheatgrass cover or production [94]. In the northern Great Plains, best response of western wheatgrass may sometimes be observed after late summer (August-September) burns [76].

Winter burns produce no change or result in increases in cover in South Dakota [63].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

On a clay upland range site with a shortgrass mixture of buffalo grass and blue grama in Kansas, a March fire consumed dry vegetation to ground level. Western wheatgrass yields did not fully recover until the 3rd growing season after the fire. For the 1st and 2nd years, it was reduced 82% and 39%, respectively [98].

In western North Dakota on a mesic mixed-grass prairie with annual precipitation of 16 inches (410 mm), the effects of 3 wildfires (May, August, and September) were studied on areas subject to trespass grazing. Frequency of western wheatgrass plants remained the same or higher than before burning on all 3 treatments.

In western South Dakota, yield and density of western wheatgrass were increased by late winter or early spring burns [22]. Western wheatgrass and Japanese brome (Bromus japonicus) were codominants in Badlands National Park in west-central South Dakota on land that had not been cultivated or grazed for at least 25 years. A study investigating the effects of fire on western wheatgrass found that vegetative propagation of western wheatgrass was enhanced immediately following burns and growth returned to the level of unburned plots during the 2nd growing season. Plots were burned in April and May, 1983 and 1984, and clipped in April 1983. Western wheatgrass spread vegetatively during the 1st growing season but often did not produce seed until the 2nd growing season following burning [152].

Although growth of new shoots from rhizomes can sometimes be retarded by early spring burning, this effect often does not persist, as fall- and spring-burned plants have similar yields after mid-May. In eastern Montana, spring-burned plants quickly overcame initial slow growth and herbage yields equaled those on fall-burned plots [163]. By mid-June spring burned plots may have higher yields of western wheatgrass than adjacent unburned plots [128,161,170]. In an eastern Montana study, spring and fall-burned plots produced significantly more (P < 0.05) forage than unburned plots, but by the end of July, no differences were noted [163]:

season and treatment      percent basal cover         
fall burn                 19.0%
spring burn               14.3%
clipped not burned        14.4%
untreated control         15.3%

FIRE MANAGEMENT CONSIDERATIONS:

Burns in the spring after new growth is initiated can severely injure western wheatgrass [148]. Bushey [28] reported that prescribed fire generally has a positive impact on the frequency and aboveground biomass of western wheatgrass in Nevada.

In the northern Great Plains, forage yield can be increased with the use of fire and careful timing of reintroduction of livestock to the burned range [151]. Areas burned can become attractive to grazers where yields and density of western wheatgrass increase [22]. After fire, western wheatgrass recovers more rapidly on ungrazed pasture than on grazed plots [32].

Forage quality can be improved with burning [151]. Burning (with or without mechanical treatments) can increase the crude protein content of western wheatgrass within the first postfire growing season. Results from a South Dakota area burned in the spring of 1984 are as follows [60]:

Mean crude protein (%) clipped at ground level:

                 Treatment
				
burning      none  burn  burn    burn     burn 
mechanical   none  none  contour pitting  rip &
                         furrow           furrow
1984        8.19   8.56  10.25   8.94    9.54
1985       12.94  10.50  10.81  10.37    9.81

Fine fuel amounts should total at least 600 lbs/acre for good fire spread in rhizomatous wheatgrass [133].

Related categories for SPECIES: Pascopyrum smithii | Western Wheatgrass