USDA Forest Service and University scientists and managers synthesized 100 years of published forestry science to help forest managers better understand the ecology of “frequent-fire” forests. This forest type, found throughout the western United States, historically experienced frequent, but low-severity surface fire events. The report provides a science-based framework that will assist land managers in developing management plans and practices to restore an uneven-aged forest structure including tree groups and grass-forb-shrub interspaces between the groups. This structure characterized these forests before the introduction of intensive management in the 19th and 20th centuries. Returning frequent-fire forests to their historical species composition and structure will increase their resilience to fire, insects, disease, and climate change.
Today’s western ponderosa pine and dry mixed-conifer forests - forests that historically experienced frequent low-severity surface fires - have undergone changes in their species composition and structure that increases their susceptibility to severe, large-scale wildfires and insect and disease episodes. A new framework informs management to improve the resistance and resilience of these forests in the Southwest to severe disturbances by restoring the species composition, structure, and spatial pattern of their vegetation. The framework recreates groups of fire-adapted tree species with interlocking crowns; grass-forb-shrub openings between tree groups; scattered individual trees within the grass-forb-shrub matrix; and snags, logs, and woody debris. Restoring these elements facilitates the return of the types and frequencies of disturbances that these forests evolved with, thereby lowering the probability of catastrophic loss and better positioning them to adapt to climate change.