Wildland Fire Management Plan Craters of the Moon National Monument IV. Historic Role of Fire

The fire season at Craters of the Moon National Monument (CRMO) extends from mid-June through mid- September. Research indicates that vegetation similar to that on the monument has burned about every 25 to 75 years during pre-European conditions (Houston 1973, Wright and Bailey 1982). With the exception of areas in the northern portion of the monument, the vegetation is isolated into pockets by lava flows and cinder gardens. Fires burning in many of these small patches of vegetation would have little chance of spreading. The discontinuous fuels and low fuel loads on the monument have probably resulted in fire-free- intervals greater than those previously reported for similar vegetation types.

There are some relatively large areas of contiguous vegetation. One of these is the Little Prairie area located in the southeast corner of the monument. In 1992, a wildland fire burned 2000 acres of Little Prairie over a span of three days.

There is clear evidence of recent fires in the Split Butte area. Many charred limber pine boles can be observed in vegetation now dominated by sagebrush or grass vegetation. These burns appear to be somewhat older than those pre-1992 fires in Little Prairie. In the immediate area of Split Butte there is heavy herbaceous cover, mainly bluebunch wheatgrass and arrowleaf balsamroot. Both species which are good indicators of past fire occurrence.

Small areas around Two Point Butte and Fissure Butte also show a history of recent fire. These burns, however, were much more localized due to surrounding younger lava flows and cinder. Farther north around Crescent Butte, the evidence of fire is also common and there are numerous charred boles of limber pine. There is evidence of low intensity fires in this area as reflected in surviving fire-scarred plants.

The Big Cinder Butte area has also burned, within the last 100 years. Most of the recent fire evidence on Big Cinder Butte is confined to the southwest slopes. The area west of the Tree Molds parking area has also burned in the same time interval. Vegetation has been set back by fire and a community dominated by rubber rabbitbrush has replaced the big sagebrush vegetation. Some charred limber pine boles and sagebrush stems are present here. A fire boundary can be observed on the hillside southwest of the trailhead.

There is less evidence of fire between Big Cinder Butte and Park headquarters than in any other area on the monument. This is probably due to the small amount of vegetated area which is separated by recent lava flows and cinder gardens. If ignitions occurred, the area burned would have been small.

The plant communities north of the highway seem to be more influenced by fire than those to the south. All vegetation types in this area show evidence of burning, with the exception of the dwarf sagebrush types along ridgetops which apparently seldom burn (Gipe 1976, Bunting et al. 1987). In most locations, these types offer excellent fuel breaks, not only because of reduced fuel, but also due to their location. In most cases, fires initiated on lower slopes would not burn through these areas. In most years, herbaceous production will be too low to allow the fire to spread across the ridgetop to the slope on the other side and back into a community with higher fuel loadings. The remaining vegetation types in the northern portion, such as Great Basin wildrye, aspen, Douglas-fir, and other sagebrush types, show evidence of past fire occurrence. In many locations, charred sagebrush stumps are still rooted in the soil. On some of the older burns in the southern parts of the monument, sagebrush stumps have been dislodged and are disintegrating, indicating older burns.

Most aspen types in the north end show evidence of past fire occurrence. This is indicated by even-aged stands (all trees seem to be the same size and age), charcoal remnants in understory, reduced down woody fuels, and in some areas an increase in snowbrush. Increment cores of aspen and cross sections of sagebrush were collected in the vicinity of the CRMO Research camp. These data indicate that most of the woody plants have become established in the last 25 to 30 years. The increase of aspen on the perimeter of the individual clones in this portion may be a cumulative result of the absence of fire and not the result of plants resprouting following the last fire.

Fire scars were dated on several Douglas-firs in Little Cottonwood Canyon using the increment core technique (Barrett and Arno 1988). Based on work done by Barrett and Arno fire has occurred every 30 to 35 years prior to Euro-American influence. Fire reedgrass, a species enhanced by fire, is common as an understory species in the aspen and Douglas-fir types. There is little recent fire evidence in this area. Fire may have been actively controlled by man during the period between Euro-American settlement and monument creation. Fires were more probably reduced inadvertently, however, by reduction of fine fuel loading by grazing livestock. The east facing slopes of Little Cottonwood Creek show much evidence of fire, indicating that the road and Little Cottonwood Creek might have served as fuel breaks.

In general, the influence of fire at CRMO is consistent with other areas of the Snake River Plain. The effect of fire can be observed in almost all vegetation types. Fire has influenced the establishment of introduced cheat grass (Bromus tectorum) in much of the central and western portions of the Snake River Plain. Cheat grass has replaced native shrub species following fire and resulted in the loss of significant sagebrush steppe habitat. In the higher elevation areas of the upper Snake River Plain cheat grass has proven less competitive. Cheat grass is found throughout the monument but is not found in dominant stands.