Historical fire regimes at the landscape scale were estimated to determine whether modern fires are unnaturally severe in the San Juan Mountains of Colorado. This study concludes that large, infrequent severe fires occurred historically, providing ecological benefit, but have burned at lower rates in the last few decades. This study utilized existing tree scar data and other types of available information resources.
Restoring and managing low-severity fire in dry-forest landscapes of the western USA
William Baker, 2017
Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA. This study uses a regression methodology to estimate fire rotations across the western US, and finds that fire burned much less frequently historically than previously thought. Past tree scar studies in northern New Mexico have indicated that fire rotations were from 5-15 years in dry mixed conifer and ponderosa pine. This study estimates that the average historical fire rotation in the Santa Fe watershed is 55 years.
Modeling results in this study confirmed that fire-fuel treatment encounters are rare, such that median fire suppression cost savings resulting from fuel treatments are zero. Sierra National Forest was used as study site to reflect a microcosm of many of the challenges surrounding contemporary fire and fuels management in the western U.S.
Discussion of studies that concludes with strong support of the historical importance of high-severity fire in ponderosa pine and mixed-conifer conifer forest fire regimes in forests of the western U.S.
A 2015 study by researchers at Harvard T.H. Chan School of Public Health found that death rates among people over 65 are higher in zip codes with more fine particulate air pollution (PM2.5) than in those with lower levels of PM2.5. PM2.5 is the most harmful component of wood smoke, including smoke from prescribed burns. The harmful effects from the particles were observed even in areas where concentrations were less than a third of the current standard set by the Environmental Protection Agency (EPA).
Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use. Increased fire could also be hypothesized as restorative of historical fire.
The study uses fire scar analysis to reconstruct fire history and fire-climate relationships in the Santa Fe River watershed in order to provide historical ecological data for guiding management. It is a component of the scientific basis for estimates of historical fire rotations for the Santa Fe National Forest.
Fire Probability, Fuel Treatment Effectiveness and Ecological Tradeoffs in Western U.S. Public Forests Rhodes and Baker 2008
Study concludes there is a very low probability of a thinned site actually encountering a fire during the narrow window when tree density is lowest.
Study finds fuel treatments in mixed-conifer forests can be somewhat effective for up to ten years, but effectiveness does not extend significantly beyond treated area, supporting Jack Cohen’s research conclusions that thinning is mostly useful in a limited radius around structures and values. Thinning without slash treatment is likely not effective and increases wildfire severity substantially outside boundaries of treated areas.
Study results illustrate broad evidence of mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America. Prior to settlement and fire exclusion, these forests historically exhibited much greater structural and successional diversity than implied by the low/moderate-severity model.
WUI fire loss problem can be defined as a home ignitability issue largely independent of wildland fuel management issues. The home and its surrounding 40 meters determine home ignitability. Also, it is important to not intermix the purposes of protection of structures and values with forest restoration.