Fraxinus pennsylvanica woodlands are an important component of the Northern Great Plains ecosystem and critical habitat for many species of birds, mammals and plants. Many F. pennsylvanica woodlands are decadent, declining from closed-canopy to open-canopy stands with few tall shrubs and a ground layer dominated by Eurasian meadow grasses. Fire has been suggested to facilitate regeneration of these woodlands. Understanding the effects of fire on tree recruitment is essential if controlled burning is to be used for regenerating F. pennsylvanica woodlands. In 2001 I subjectively chose one stand with evidence of ground fire and a similar unburned stand at each of seven sites where F. pennsylvanica woodlands had experienced warm-season wildfire between 1988 and 1998. I measured density of F. pennsylvanica seedlings and number and size of crown sprouts for each tree in 3–4 sample plots in each stand.
Fire had a significant negative effect on Fraxinus pennsylvanica regeneration at most sites. Trees in burned stands had three times as many crown sprouts (P = 0.02) that were nearly twice as large in diameter (P = 0.09) than in unburned stands. However, seedlings averaged 75% fewer in burn plots compared to unburned (P = 0.06). Burn plots with live mature F. pennsylvanica trees remaining had twice as many seedlings compared to those in which all mature trees were top-killed (P = 0.08). A large number of F. pennsylvanica trees were apparently killed by fire at several of the study sites. This study did not support using fire to restore F. pennsylvanica woodlands in eastern Montana.