Twelve years biomass response in aspen communities following fire.

Abstract

Vegetation responses to prescribed fire over a 12-year period are reported for several deteriorating aspen clones in northwestern Wyoming. This study extends earlier work by Bartos and Mueggler (1981) on a prescribed fire intended to regenerate these aspen clones. After 3 years, numbers of suckers were close to pre-burn levels ranging between 10,000 to 20,000 suckers/ha. After 12 years, 1,500 to 2,400 suckers/ha remained at a meager height averaging approximately 0.5 m. The demise of this aspen was attributed to heavy ungulate use, primarily elk. Total undergrowth production increased substantially by the second postfire year and declined slowly after that. Biomass values of 2,130 kg/ha (low burn severity), 2,140 kg/ha (moderate burn severity), and 2,190 kg/ha (high burn severity) were recorded after 12 years. This exceeds preburn production by 23 to 46%. Forbs made up approximately 75% of the undergrowth production after 12 years, which was dominated by a dramatic postburn shift to fireweed (Epilobium angustifolium L.). The remaining production was comprised of approximately 20% grasses and 5% shrubs. Most of the fluctuation in species composition occurred on the high severity burn sites.