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Wildlife, Animals, and Plants |
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FIRE ECOLOGYFIRE ECOLOGY OR ADAPTATIONS:
Bluebunch wheatgrass usually survives fires because its buds are protected by soil and/or plant material. Fire frequencies for bluebunch wheatgrass-dominated habitats vary considerably, depending on the associated species [54]. Most mean fire intervals (MFI's) are less than 30 years. In eastern Idaho, MFI prior to fire suppression in a ponderosa pine/bluebunch wheatgrass habitat at 3,480 feet (1061 m) was 17.6 years. In a Douglas-fir/bluebunch wheatgrass habitat at 4,800 feet (1464 m), the MFI was 13.2 years [27]. At slightly lower elevations (around 3,000 feet (915 m)) along the Salmon River, in the nearby River of No Return Wilderness, the MFI in 3 Douglas-fir/bluebunch wheatgrass sites ranged from 9.6 to 21 years. In northern Idaho Douglas-fir and ponderosa pine habitat types, MFI's are estimated from 14-22 years for nonlethal surface fires [212]. Estimates for presuppression fire intervals in the Snake River Canyon of Idaho for bluebunch wheatgrass, Idaho fescue (Festuca idahoensis), Sandberg bluegrass, and plains prickly-pear are 10 to 25 years [151]. Burkhardt and Tisdale [56] estimate a prefire suppression MFI of less than 30 years in a big sagebrush/bunchgrass community in southwestern Idaho. Prior to invasion of annual exotic grasses such as cheatgrass, big sagebrush/bunchgrasslands in the Snake River Plain, Idaho, probably did not have enough fuel to carry fire frequently [195,227]. Peters and Bunting [195] estimate a fire frequency of 20 to 100 years in southwestern Idaho. Average fire occurrence (yrs.) <10 25 50 100 no change increase increase decreaseThe Fire History Database of the Western Unites States includes MFI information for Montana and Wyoming bluebunch wheatgrass habitat types. In Montana, on several Douglas-fir/bluebunch wheatgrass sites, fire regimes were characterized as moderate severity, frequent surface fires, with an MFI of less than 1 to 23 years [134]. Arno [15] estimates mean fire-free interval in the years 1735-1900 to be from 6 to 11 years in the Douglas fir/bluebunch wheatgrass habitat type at 3,800 to 5,000 feet (1159-1525 m) in the Bitterroot National Forest, Montana. The shorter end of that range, 6 years, may have been affected by frequent Native American burning; the study sites that provided the longer intervals were not likely to have been burned by Indians. Also in western Montana, Arno and Gruell [17] estimated mean fire interval from 1588 to 1877 in a hot, dry, limber pine/bluebunch wheatgrass site to be 74 years. The authors warn that the length of the interval may be overestimated, since old-growth trees (on which fire history is based) are rare in the harsh habitat, and often occupy rocky, inhospitable sites that are fire refugia. In an area with low fuel accumulation, more frequent, less intense fires may not result in fire scars, and therefore the fires would not be recorded. On Wyoming bluebunch/Idaho fescue sites, the fire regime featured low-severity, infrequent surface fires, with MFIs from 17 to 62 years [134]. Parminter [190] suggests a MFI of 6 to 15 years in ponderosa pine/bluebunch wheatgrass types in British Columbia. Prior to European settlement and fire suppression, bluebunch wheatgrass plant associations produced enough fuel to burn annually in the Blue Mountains of Oregon, but they were unlikely to do so. Early in the season, high moisture content of the grass reduced the flammability of the plants [3].
POSTFIRE REGENERATION STRATEGY:Tussock graminoid
Related categories for SPECIES: Pseudoroegneria spicata | Bluebunch Wheatgrass |
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