The Effect of Fire on an Ungrazed Western Montana Grassland

Abstract

On 28 June 1977 a hot wildfire burned part of a species-rich foothills grassland dominated by Festuca scabrella, F. idahoensis and Agropyron spicatum. We sampled plant species cover in paired stands, on and off the burn, during 1977 and 1978 to determine the initial impact of the fire, and during 1980 to document recovery after 3 years. Grass cover decreased on the burn due primarily to a sharp drop in the cover of the two dominant fescues. Forb cover increased. Moss and lichen cover dropped greatly. Much of the difference in species response was related to plant growth form and phenology. Large bunches of F. scabrella were more seriously damaged than small ones, indicating long intervals between fires are detrimental to the species when fire does return. At burned sites, afternoon soil temperatures were higher and near-surface soil moisture was lower. Three years after the fire, cover of most vascular species was similar in burned and unburned stands. Festuca idahoensis had recovered completely. Festuca scabrella had increased but was still well below unburned levels. Total moss cover on the burn was nearly that on unburned sites, but the species composition was greatly altered. Lichens were still reduced. The stability of the grassland in relation to fire is discussed.