Ecological research has implicated the practice of fire exclusion as a major contributor to forest health problems in the semiarid ponderosa pine (Pinus ponderosa) zone of the Inland West (Mutch and others 1993; Sampson and others 1994). Prior to 1900, frequent, low-intensity fires occurred on upland forests in this forest zone at intervals of 5 to 30 years. With fire exclusion, dense understories and thickets of conifers have developed, producing stands that are highly susceptible to a variety of insect and disease epidemics-and severe wildfires. These concerns have led to proposals and a few operational programs to reintroduce fire on a large scale to restore these forests (Kilgore and Curtis 1987; Lolo National Forest 1994; Williams 1995).