• 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:

Grouse whortleberry is described as moderately resistant to fire [39,135]. Underground rhizomes generally survive low- to moderate-severity fires that do not consume the lower duff [39]. However, most grouse whortleberry rhizomes extend no deeper than between duff and mineral soil [40,87]. Because rhizomes are shallow, this shrub is susceptible to severe, duff-reducing fires that eliminate rhizomes and seriously damage or kill the plant [64,77].

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

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PLANT RESPONSE TO FIRE:

Postfire response of grouse whortleberry is related to fire severity and intensity. Initial declines in cover have been noted [10,21,109]. After severe, stand-replacing crown fires, the species can recover (from rhizomes) in as little as 5 years [68,87]. In a western Montana lodgepole pine forest, grouse whortleberry was the most ubiquitous plant species detected 12 years and 21 years after a severe burn. Percent cover of grouse whortleberry after 21 years averaged from 1% to 33%. The higher percent cover was in areas undisturbed by postfire management activity, identified as road building, salvage logging, pole cutting, cattle grazing, and herbicide use, which were characterized as "calamitous" for grouse whortleberry recovery [78].

In a Wyoming study postfire sprout density of grouse whortleberry declined with increasing fire severity. In that study, all grouse whortleberry plants observed were from sprouting rhizomes. No seedlings were observed, in either burned or unburned sites [123].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

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FIRE MANAGEMENT CONSIDERATIONS:

In seral Rocky Mountain lodgepole pine forests in northern Idaho, grouse whortleberry is widespread. Fuel loadings are discontinuous and may be heavy, enhanced by deep duff and subalpine fir and mountain hemlock regeneration. Management-ignited fire is used to increase water yield, provide wildlife forage, prepare seedbeds for regeneration, and reduce fuels. Duff moisture content is an important fire management consideration. Intense soil heating in these forests kills the roots and rhizomes of shrubs and herbs, notably Vaccinium species [115].

In persistent or climax upper-elevation Rocky Mountain lodgepole pine forests in northern Idaho, where grouse whortleberry cover is abundant, fuel loadings are often light and discontinuous. Elevation of these stands is above 5,000 feet (1,500 m). Unlike seral lodgepole pine forests which usually have a strong understory of shade-tolerant subalpine fir, these stands have only scattered subalpine fir. Litter and duff are shallow. Prescribed fire is used on these sites for hazard reduction and site preparation related to logging [115]. Upper-elevation, persistent Rocky Mountain lodgepole pine forests with abundant grouse whortleberry also occur in western Wyoming, southeastern Idaho, and western Montana [99,116].

In northern Idaho's highest subalpine forests, grouse whortleberry is a common component under a mixed overstory. Tree species include Rocky Mountain lodgepole pine, whitebark pine, Engelmann spruce, subalpine fir and mountain hemlock. Fuels are characterized by sparse fine materials and moderate to heavy loadings of larger fuels. Management objectives are similar those listed above, but timber production is rarely important. Fire return intervals are long, more so because of fire suppression. These forests are susceptible to fires that originate at lower elevations as well as fires that ignite on site [115]. Grouse whortleberry can increase the flammability of litter and influence the spread of surface fires by lending physical support to fine fuels such as twigs and conifer needles, creating a better aerated, loose surface layer. The shrub contributes to combustion once preheating is overcome. Regression equations have been developed to describe the fuel characteristics of grouse whortleberry [3,38].

Related categories for SPECIES: Vaccinium scoparium | Grouse Whortleberry