Results/Conclusions Surveys in Jeffrey pine forest indicate that clearings are four times more common in recently burned forest than in unburned forest. In addition, the proportion of trees with clearings declines with time since the last fire, indicating that recurrent fire is necessary to maintain clearings. Thus the exclusion of fire from forests eliminates these features and their ecological effects. Formica sibylla ant nests are found in a majority of clearings, and results from field experiments suggest that ants play a role in removing needles deposited in clearings. However, this behavior appears to be independent of ant nest site and may instead be related to creating optimal ant foraging space. Although the exact motivation behind ant clearing behavior remains to be determined, it appears that ant ecosystem engineering dramatically alters fire severity and tree fitness. This highlights an unexpected benefit of reintroducing fire to an ecosystem where it was once an integral process.