Countering Omitted Evidence of Variable Historical Forests and Fire Regime in Western USA Dry Forests: The Low-Severity-Fire Model Rejected  William L. Baker, Chad T. Hanson, Mark A. Williams, Dominick A. DellaSala, April 3, 2023
The “low-severity” model is that dry forests were relatively uniform, low in tree density, and dominated by low- to moderate-severity fires; the “mixed-severity” model is that dry forests were heterogeneous, with both low and high tree densities and a mixture of fire severities. Here, we simply rebut evidence in the low-severity model’s latest review, including its 37 critiques of the mixed-severity model.
Cumulative Severity of Thinned and Unthinned Forests in a Large California Wildfire   
Chad T. Hanson, Mar 3, 2022
A study of the 2021 Antelope Fire in California shows that areas commercially thinned were associated with significantly higher overall tree mortality levels than unthinned areas.  
Disentangling Post-Fire Logging and High-Severity Fire Effects for Spotted Owls   Chad T. Hansen, Derek E. Lee, and Monica L. Bond, Apr 14, 2021
The authors document that articles reporting negative effects of high-severity fire on spotted owls were pervasively confounded by post-fire logging. Results indicate a need to approach analyses of high-severity fire and spotted owls differently in future research.
Are Wildland Fires Increasing Large Patches of Complex Early Seral Forest Habitat?   Dominick A. DellaSala and Chad T. Hanson, 2019
There has been no significant increase in the size of high intensity fire patches since the early 1990’s. This has management implications that logging and thinning may not be necessary to protect against larger high intensity fires.

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.
Does increased forest protection correspond to higher fire severity in frequent-fire forests of the western United States?   Bradley, Hanson and DellaSala 2016
This large-scale study concludes that Western frequent-fire forests, including Southwestern forests, with the highest levels of protection from logging tend to burn least severely—logging defined to include the removal of trees, including small trees for non-commercial fuel.
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).

Area burned in western United States is unaffected by recent mountain pine beetle outbreaks   Hart, Schoennagel, Veblen and Chapman  2015
Study results demonstrate that the annual area burned in the western United States has not increased in direct response to bark beetle activity, bringing into question whether dead trees in general increase fire hazard.
Are High-Severity Fires Burning at a Much Higher Rates Recently Than Historically in Dry-Forest Landscapes?   William Baker  2015
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.
Ponderosa Pine Ecosystems  Graham and Jain, U.S. Forest Service, 2005
The effects of fire exclusion, animal grazing, timber harvest, and climate cycles on pondersosa pine ecosystems in the Southwestern United States
Examining Historical And Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed Conifer Forests   Odion, Hanson, Arsenault, Baker, DellaSala, Hutto and Klenner  2004
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.
Preventing Disaster: Home Ignitability in the Wildland-Urban Interface  Jack D. Cohen, U.S. Forest Service Department of Agriculture, 2000
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 restorations
Songbird ecology in Southwestern Ponderosa Pine Forests – A Literature Review  William M. Block, Deborah M. Finch, U.S. Forest Service Department of Agriculture, May, 1997

The Forest Advocate
Santa Fe, New Mexico