• FIRE ECOLOGY OR ADAPTATIONS
• POSTFIRE REGENERATION STRATEGY

FIRE ECOLOGY OR ADAPTATIONS:

Although the seed is generally viable, postfire regeneration of grouse whortleberry from seed is rare because germinants are fragile. The species relies on prolific rhizomes to survive fire. Following low- or moderate-severity fires that do not kill the shallow rhizomes, grouse whortleberry sprouts quickly and vigorously. The rhizomes occur in duff or at the duff-soil interface [25,39,87,109,115]. Severe fires can eliminate this shrub from a site [115]. Please refer to the Fire Effects section of this report for more information.

Wildfire regimes in forests where grouse whortleberry is common are variable in frequency and severity, including nonlethal understory, severe stand-replacement, and mixed-severity fires [17].

Persistent (rather than seral) lodgepole pine forests in northern Idaho and western Montana have mean stand-replacing fire intervals of 195 years, with low-severity fires at 40- to 50-year intervals. Grouse whortleberry cover often exceeds 50% in these stands [115].

Fire return intervals for crown fires in the high, volcanic plateau lodgepole pine forests of Yellowstone National Park were estimated at 300 to 400 years. The more frequent low-severity surface fires are thought to exert a minor influence on long-term vegetation structure. After the slow development of sufficient large fuels (largely lodgepole pine, subalpine fir, and Engelmann spruce), stand-replacing fires are probably ignited in small fuels by lightning strikes. In these forests, grouse whortleberry decreases as fire severity increases [108,123].

Drier montane sites, dominated by lodgepole pine and whitebark pine, often have stand-replacing fire return intervals greater than 200 years [13,91]. Where whitebark pine is climax, fires are infrequent and generally of low intensity. When fires do occur, many trees die and regeneration is low [91].

Fire regimes for plant communities and ecosystems in which grouse whortleberry is likely to occur are summarized below. For further information regarding fire regimes and fire ecology of communities and ecosystems where grouse whortleberry is found, see the `Fire Ecology and Adaptations' section of the FEIS species summary for the plant community or ecosystem dominants listed below.

Community or Ecosystem	Dominant Species	Fire Return Interval Range (years)
silver fir-Douglas-fir	Abies amabilis-Pseudotsuga menziesii var. menziesii	> 200
grand fir	Abies grandis	35-200
western larch	Larix occidentalis	25-100
Engelmann spruce-subalpine fir	Picea engelmannii-Abies lasiocarpa	35 to > 200
whitebark pine*	Pinus albicaulis	50-200 [17]
Rocky Mountain lodgepole pine*	Pinus contorta var. latifolia	25-300+ [8,108]
western white pine*	Pinus monticola	50-200
Rocky Mountain ponderosa pine*	Pinus ponderosa var. scopulorum	2-10
Rocky Mountain Douglas-fir*	Pseudotsuga menziesii var. glauca	25-100
mountain hemlock*	Tsuga mertensiana	35 to > 200 [17]

*fire return interval varies widely; trends in variation are noted in the species summary
**(mean)

POSTFIRE REGENERATION STRATEGY [120]:

Rhizomatous shrub, rhizome in soil
Initial-offsite colonizer (off-site, initial community)

Related categories for SPECIES: Vaccinium scoparium | Grouse Whortleberry