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Wildlife, Animals, and Plants |
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FIRE EFFECTS
IMMEDIATE FIRE EFFECT ON PLANT:Rough fescue is initially top-killed by fire [107]; however, rough fescue is moderately resistant to fire. Rough fescue crowns are made up of coarse culm bases that persist from year to year. These crown characteristics make rough fescue less susceptible to prolonged burning than a fine-leaved bunchgrass such as Idaho fescue [126]. Coarse stubble accumulations presumably insulate perennating buds located near the ground surface [82]. Most plants survive fires that occur during dormancy or under the high-moisture conditions often associated with spring and fall burning [12,64,72]. Although densely packed stubble accumulations help to insulate the perennating buds when fire severity is low, with very dry burning conditions the dense stubble accumulations can generate high-severity fires [107]. Fires that penetrate the duff layer and burn into the root crowns increase belowground temperatures that can damage belowground tissues [18,107]. Fire damage can be particularly severe and mortality can occur on sites where reduced fire frequencies have produced heavy litter buildups within large-diameter rough fescue crowns [6].
DISCUSSION AND QUALIFICATION OF FIRE EFFECT:Rough fescue can be severely damaged by hot, mid-summer wildfires. Rough fescue cover was significantly reduced by spring burning on rough fescue-dominated foothills grassland in western Montana. At postfire year 1, rough fescue cover was 8.1% on burned areas and 24.6% on unburned areas. The site had been protected from fire for 32 years and had been ungrazed for almost 80 years. Rough fescue plants were characterized by large-diameter bunches with substantial accumulations of old culm stubble. Mortality occurred where crown diameters exceeded 7.8 inches (20 cm), and many of these plants had burned to below the soil surface. Complete consumption of some bunches produced holes in the ground from 1 to 2 inches (3-5 cm) in depth that were filled with as much as 1 inch (3 cm) of ash [6].
PLANT RESPONSE TO FIRE:Rough fescue recovers from fire by tillering, sprouting from the root crown, and regenerating from seed [1,44,98,106,107]. It is initially reduced by fire regardless of the season of burning. Although preburn cover is typically regained within 2 to 3 years on most sites [107], burning season and fire severity can influence the rate of recovery. Despite burning at high temperatures, rough fescue can sometimes initiate conspicuous green shoots within a week after the fire. Rough fescue is unharmed by burning if the plant is dormant [4]. Spring burns can adversely affect flower development, and seed production can be reduced. Spring burns may be more detrimental due to elevated growing points that increase susceptibility; however, in a southeastern British Columbia study, spring burns had no significant effect on rough fescue cover [107]. Fall burns appear to have no effect on seed production [12,107]. Elevated soil moistures which are associated with fall burns may also reduce damage. Early spring growth and flower development were reported following the fall burn in British Columbia. Earlier growth was attributed to increased soil temperatures resulting from greater heat absorption from the blackened surface [107]. Nonrhizomatous northern and mountain rough fescue appear more susceptible to fire damage than plains rough fescue. Plants are particularly prone to fire damage on sites where reduced fire frequencies have produced large diameter bunches with heavy stubble accumulations. Antos and others [6] observed decreased resprouting response with increasing bunch size following a hot, mid-season wildfire in Montana. Crowns less than 4 inches (10 cm) in diameter resprouted completely, whereas resprouting was inhibited in crowns greater than 7.8 inches (20 cm) in diameter. Three years after the fire, average coverage of rough fescue on burned sites was 11.1% versus 29.9% in unburned areas. Herbage production can remain below unburned levels for 2 to 3 years when mid-season burning generates high severity fires [20].
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:Rough fescue cover can be severely reduced when burning occurs during the growing season. On quaking aspen parkland of southern Alberta, Bailey and Anderson [12] reported a 26% decline 1 year after a spring burn compared to a 6% decline after a fall burn. Rough fescue cover was reduced for at least 3 years: herbage production on burned sites remained below production on unburned areas. New rough fescue growth on burned sites was approximately 4 inches (10 cm) in height at postfire year 3. In contrast, burning on similar sites immediately after snowmelt, when leaf growth was approximately 1.5 inches (4 cm), slightly reduced rough fescue cover but maintained prefire annual production during postfire year 1. Generally, plains rough fescue responds to fire by increased tiller production. Burned swards are shorter and denser than unburned swards. Apparently the further into the growing season the burning occurs, the greater the detrimental effect. Grilz and Romo [44] reported reduced tillering of plains rough fescue following spring or fall burns in communities with patchy smooth brome. Sinton [98] observed a nearly linear relationship between herbage production, leaf blade length, and tiller density following burning 1 week, 4 weeks, and 8 weeks after snowmelt. Drastic reductions in seed production can occur after spring burns. Bailey and Anderson [12] reported a 92% reduction in seedstalk production 3 months after a spring burn in southern Alberta. Following a spring burn in Saskatchewan, biomass in grasslands dominated by plains rough fescue was reduced by 72 to 84% [92]. Like many cool-season grasses, rough fescue initiates floral development in the fall. Studies of rough fescue indicate that growing points are gradually elevated during the winter from 0.4 inches (12.6 mm) above the root crown transition in October to 1.5 inches (40 cm) in May [60]. Bailey and Anderson [12] suggest that floral initiation is not affected by spring burns; but by May, the greater height of reproductive growing points leaves them them susceptible to fire damage. Seed development on burn sites approximated that on unburned stands within 2 growing seasons. Fall burns had no effect on subsequent seed head development. In Montana, rough fescue decreased 17.5% in the 1st season after fire. During the 2nd growing season after fire, a 5% reduction was noted when compared to preburn levels [21]. The following densities (stems/m2) were reported for rough fescue following spring and fall burning in Saskatchewan [44]:
spring burn fall burn unburned
(1988) (1987)
Aug. 87 1065 1860 1190
Sept. 88 1425 1180 1170
Aug. 89 1275 1905 1110
FIRE MANAGEMENT CONSIDERATIONS:Annual spring burning studies on quaking aspen parkland sites in Alberta indicate that short fire cycles impede rough fescue reestablishment , while long fire return intervals produce high mortality due to excessive fuel buildup. In plains rough fescue prairie communities, large concentrations of dead plant material develop in the absence of fire and/or grazing [46]. Prescribed fire frequencies of 5 to 10 years are recommended for mountain grassland sites where management objectives are aimed at rough fescue maintenance [5]. Spring burns should be conducted as soon after snowmelt as possible to minimize fire damage [12]. The degree to which plants recover typically declines as the growing season progresses [5,98]. In northwestern Montana, fall burns can increase the chances of soil erosion by wind or water, leaving rough fescue more susceptible to frost damage. Fall burns may also reduce important elk forage, including rough fescue, during the 1st winter after burning [63]. Protein content (%) of rough fescue may be increased by burning. In central Montana, protein content ranged from 6.0 to 8.9% on unburned control sites, and from 8.1 to 14.6% on burned sites [66].
Related categories for SPECIES: Festuca altaica | Rough Fescue |
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