Fuel moisture, forest type, and lightning-caused fire in Yellowstone National Park

Abstract

The occurrence and behavior of lightning-caused fires in Yellowstone National Park were summarized for 17 years (1972–1988) during a prescribed natural fire program. Both ignition (occurrence) and spread (stand replacing fire activity) of fires were strongly influenced by fuel moisture and forest cover type. Fuel moisture estimates of 13% for large (>7.6 cm) dead and downed fuels indicated a threshold below which proportionately more fire starts and increased stand replacing fire activity were observed. During periods of suitable fuel moisture conditions, fire occurrence and activity were significantly greater than expected in old-growth, mixed-canopy lodgepole pine (Pinuscontorta Dougl. var. latifolia) and Engelmann spruce–subalpine fir (Piceaengelmannii Parry–Abieslasiocarpa (Hook.) Nutt.) forest types, and significantly less than expected in the successional lodgepole pine forest types. During periods of extended low fuel moisture conditions (drought), sustained high winds significantly reduced the influence of forest cover type on stand replacing fire activity. These extreme weather conditions were observed during the later stages of the 1988 fire season, and to a lesser extent, for a short duration during the 1981 fire season. The Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest type typically supported little stand replacing fire activity, even though a preponderance of fire starts was observed.

Monitoring forest regrowth following large scale fire using satellite data-A case study of Yellowstone National Park, USA-

“…1). The 1988 fires in YNP burned approximately 250,000 ha (roughly 36% of the park) of coniferdominated forest, largely due to extreme drought and high winds [Renkin and Despain, 1992;Bessie and Johnson, 1995]. Fires of this magnitude occur in Yellowstone every 250 -400 years, with the last such event happening in the early 1700's [Houston, 1973;Romme, 1982].…”

“…Fires of this magnitude occur in Yellowstone every 250 -400 years, with the last such event happening in the early 1700's [Houston, 1973;Romme, 1982]. The summer of 1988 was the driest on record since 1886, with precipitation in June, July, and August at 20%, 79%, and 10% of their monthly mean [Renkin and Despain, 1992]. Almost 250 different fires started in Yellowstone and the surrounding National Forests between June and August.…”

Wildfire and spruce beetle outbreak: Simulation of interacting disturbances in the central Rocky Mountains

“…In contrast, stands with low to moderate beetle mortality (< 50% tree kill) had a lower incidence of high-severity crown fires. However, it is unclear whether these differences in fire behavior were primarily the result of the outbreak or of pre-outbreak stand structure (Simard et al 2008), because beetle mortality occurred preferentially in older stands that were, in turn, inherently more likely to burn at high severity than younger stands because of differences in fuel structures even in the absence of beetle activity (Renkin and Despain 1992 significantly lower fire severity compared to adjacent burned areas that had not been affected by beetles in the 3400-hectare Robinson Fire that burned in Yellowstone National Park in 1994 (Omi 1997). Lynch et al (2006) also examined the influence of previous beetle activity on the 1988 Yellowstone fires by testing whether beetleaffected stands were more likely to have burned than those stands not affected by beetles.…”

Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?

“…Conditional crowning is predicted when conditions allow crowning but not torching; active crown fire could potentially occur if the canopy was ignited by a firebrand or by a crown fire from an adjacent stand (Scott and Reinhardt 2001). Thus, weather conditions can constrain the effects of stand structure (i.e., fuels) on fire behavior (Renkin and Despain 1992).…”