Fire & “Fuels”

Alexander, John, Nathaniel Seavy, John Ralph and Bill Hogoboom, 2006. Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California, International Journal of Wildland Fire, 2006, 15, 237-245

These results, in combination with previous studies of fire severity in the Klamath-Siskiyou region, suggest that areas with southern aspects tend to burn with greater severity than those of other aspects, areas with large trees burn less severely than those with smaller trees, and that correlates of fire severity vary extensively among fires.[1]

[1] Alexander, John, Nathaniel Seavy, John Ralph and Bill Hogoboom, 2006. Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California, International Journal of Wildland Fire, 2006, 15, 237-245

Baker, William, 2011: “Reconstruction of the Historical Composition and Structure of Forests in the Middle Applegate Area, Oregon, using the General Land Office Surveys, and Implications for the Pilot Joe Project”,

Introduction

The Middle Applegate area of southwestern Oregon has been the site of collaboration to restore forests and watershed health (http://www.applegatepartnership.org), and part of the area is now the site of a pilot area (USDI BLM 2011) to demonstrate proposed methods for combining logging and forest restoration (Johnson and Franklin 2009).  Here I present information from the original late-19th century surveys about historical forest structure in the Middle Applegate and discuss its relevance to the proposed Pilot Joe project (USDI BLM 2011).”

The hypothesis that mature and late-successional forests existed historically as fire-susceptible patches in a matrix of low-density, fire-resistant forests (and this should be recreated today) is not supported by the historical evidence….Closed canopy, complex forests (e.g., late-successional forests) in this area were likely the least susceptible to high-severity fire (Odion et al. 2004), and they formed patches in a more extensive fire-susceptible matrix.

Final paragraph of Baker document:

“If the Pilot Joe project is going to achieve restoration while also producing wood, I suggest that the proposed alternative needs to be reshaped to be congruent with the local science-based historical information contained in this report and in previous research (Detling 1961, Hosten et al. 2007, Odion et al. 2004, 2010, Colombaroli and Gavin 2010).  These are congruent in showing that the ideas of Johnson and Franklin (2009) and summaries by BLM (USDI BLM 2011) are incorrect for the Applegate landscape, so that the proposed Pilot Joe project will not restore these forests, relative to historical conditions, nor will it create forests that are resistant and resilient to future climate change.” (P 10 [emphasis added])[1]

[1] Baker, William, 2011: “Reconstruction of the Historical Composition and Structure of Forests in the Middle Applegate Area, Oregon, using the General Land Office Surveys, and Implications for the Pilot Joe Project”

Bradley, C.M. et al. 2016. Does increased forest protection correspond to higher fire severity in frequent-fire forests of the western United States?

There is a widespread view among land managers and others that the protected status of many forestlands in the western United States corresponds with higher fire severity levels due to historical restrictions on logging that contribute to greater amounts of biomass and fuel loading in less intensively managed areas, particularly after decades of fire suppression. This view has led to recent proposals—both administrative and legislative—to reduce or eliminate forest protections and increase some forms of logging based on the belief that restrictions on active management have increased fire severity. We investigated the relationship between protected status and fire severity using the Random Forests algorithm applied to 1500 fires affecting 9.5 million hectares between 1984 and 2014 in pine (Pinus ponderosa, Pinus jeffrey) and mixed‐conifer forests of western United States, accounting for key topographic and climate variables. We found forests with higher levels of protection had lower severity values even though they are generally identified as having the highest overall levels of biomass and fuel loading. Our results suggest a need to reconsider current overly simplistic assumptions about the relationship between forest protection and fire severity in fire management and policy.[1]

[1] Bradley, C.M. et al. 2016. Does increased forest protection correspond to higher fire severity in frequent-fire forests of the western United States? Ecosphere 7:1-13.

Jack D. Cohen, Research Physical Fire Scientist with the USDA Forest Service Missoula Fire Sciences Laboratory, is the pre-eminent researcher on wildfire and home ignitions, and a founder of the Firewise Communities/USA recognition program. Jack coined the concept and phrase “home ignition zone”. You may read his papers on preventing home loss disasters during wildfire, and review his post-fire examinations of home destruction at the Firewise website.  See a range of videos on YouTube.

Cohen, Jack. 1999, from “Reducing the Wildland Fire Threat to Homes:  Where and How Much?”

Research for the Structure Ignition Assessment Model (SIAM) conclusions:

SIAM modeling, crown fire experiments, and WUI fire case studies show that effective fuel modification for reducing potential WUI fire losses need only occur within a few tens of meters from a home, not hundreds of meters or more from a home.” “These research conclusions redefine the WUI fire problem as a home ignitability issue largely independent of wildland fuel management issues.[2]

Cohen, Jack, 2000, from “What is the Wildland Fire Threat to Homes?” 

The term "wildland-urban interface" suggests that residential fire destruction occurs according to a geographical location. However, this misrepresents the physical nature of the wildland fire threat to homes. The wildland fire threat to homes is not where it happens related to wildlands but how it happens related to home ignitability. Therefore, to reliably map the potential for W-UI home fire loss, home ignitability must be the principal mapping characteristic. The information related to potential home destruction must correspond to the home ignitability spatial scale. That is, the information must relate to those characteristics of the home and its immediate site within a few tens of meters.[3]

Cohen, J.D. 2000. Preventing disaster: home ignitability in the Wildland-Urban Interface. Journal of Forestry 98:15-21.

The key to reducing W-UI home fire losses is to reduce home ignitability. SIAM modeling, crown fire experiments, and case studies indicate that a home's structural characteristics and its immediate surroundings determine a home's ignition potential in a W-UI fire. Using the model results as guidance with the concurrence of experiments and case studies, we can conclude that home ignitions are not likely unless flames and firebrand ignitions occur within 40 meters of the structure. This finding indicates that the spatial scale determining home ignitions corresponds more to specific home and community sites than to the landscape scales of wildland fire management. Thus, the W-UI fire loss problem primarily depends on the home and its immediate site.

…

Because home ignitability is limited to a home and its immediate surroundings, fire managers can separate the W-UI structure fire loss problem from other landscape-scale fire management issues. The home and its surrounding 40 meters determine home ignitability, home ignitions depend on home ignitability, and fire losses depend on home ignitions. Thus, the W-UI fire loss problem can be defined as a home ignitability issue largely independent of wildland fuel management issues. This conclusion has significant implications for the actions and responsibilities of homeowners and fire agencies, such as defining and locating potential W-UI fire problems (for example, hazard assessment and mapping), identifying appropriate mitigating actions, and determining who must take responsibility for home ignitability.

W-UI fire loss potential. Because home ignitions depend on home ignitability, the behavior of wildland fires beyond the home or community site does not necessarily correspond to W- UI home fire loss potential. Homes with low ignitability can survive high- intensity wildland fires, whereas highly ignitable homes can be destroyed during lower-intensity fires.

This conclusion has implications for identifying and mapping W-UI fire problem areas. Applying the term wild- land-urban interface to fire losses might suggest that residential fire threat occurs according to a geographic location. In fact, the wildland fire threat to homes is not a function of where it happens related to wildlands, but rather to how it happens in terms of home ignitability. Therefore, to reliably map the potential for home losses during wildland fires, home ignitability must be the principal mapping characteristic. The home threat information must correspond to the home ignitability spatial scale, that is, those characteristics of a home and its adjacent site within 40 meters.

Home fire loss mitigation. W-UI home losses can be reduced by focusing efforts on homes and their immediate surroundings. At higher densities where neighboring homes may occupy the immediate surroundings, loss reductions may necessarily involve a community. If homes have a sufficiently low home ignitability, a community exposed to a severe wildfire can survive without major fire destruction. Thus, there is a need to examine the reduction of wildland fuel hazard for the specific objective of home protection There are various land management reasons for conducting wildland vegetation management. However, when considering the use of wildland fuel hazard reduction specifically for protecting homes, an analysis specific to home ignitability should determine the treatment effectiveness.

Responsibility for home ignitability. If no wildfires or prescribed fires occurred, the wildland fire threat to residential development would not exist. However, our understanding of the fire ecology for most of North America in- &cares that fire exclusion is neither possible nor desirable. Therefore, homeowners who live in and adjacent to the wildland fire environment must take primary responsibility for ensuring that their homes have sufficiently low home ignitability.[4]

Jack Cohen, 2003, from “Thoughts on the Wildland-Urban Interface Fire Problem”

My research results indicate that the big flames of high intensity wildland fires do not directly ignite homes at separation distances beyond 100 feet.

…

The home ignition zone provides the scientific basis for developing actions that will prevent residential fire disasters. Since the home ignition zone principally determines home ignition potential, communities at risk of burning must be assessed and thereby identified based on the condition of the home ignition zones. For the same reason, mitigating home ignition potential during extreme wildland fires must focus activities within and immediate to the residential area, i.e. the home ignition zone. But the home ignition zone largely corresponds to private property. Thus, with minor exception, the authority for effectively reducing the home ignition potential belongs to homeowners. Public land management agencies can facilitate homeowner mitigations and these agencies may be able to reduce fire intensities and the extent of burning around communities. But these agencies cannot accomplish the necessary and sufficient actions necessary to prevent residential fire disasters during extreme fire conditions by treating beyond the home ignition zone.

As we discuss preventing home ignitions, we should recognize that homes are but one of the societal values impacted by wildland fire. Our communities also derive many values from the ecosystems that burn. Fires directly and indirectly impact ecosystems at landscape scales as a complex interaction of biophysical processes over the long-term. In contrast, homes ignite based on meeting the requirements for combustion as determined by the site-specific fire conditions. The home ignition zone physically defines home ignition potential distinct and separate from the impacts of fire in ecosystems and thus allows us to address the risk of burning homes (one community value) separately from landscape fire concerns (multiple community values). This suggests that how we approach fire in our ecosystems and who takes such action should be different from how we prevent residential fire disasters and who must mitigate the home ignition zone. Given that wildland fires will occur under extreme fire conditions and that fire is an ecological process, the home ignition zone indicates that we will have wildland fires and at the same time prevent residential fire disasters.[5]

[2] Cohen, J. D., 1999. Reducing the Wildland Fire Threat to Homes: Where and How Much?

[3] Cohen, J. D. 2000. What is the Wildland Fire Threat to Homes?  USDA Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT.  Lecture presented to School of Forestry, Northern Arizona University, Flagstaff, AZ on April 10, 2000. Page 8.

[4] Cohen, J.D. 2000. Preventing disaster: home ignitability in the Wildland-Urban Interface. Journal of Forestry 98:15-21.

[5] Cohen, J. D., 2003. “Thoughts on the Wildland-Urban Interface Fire Problem”

Colombaroli, Daniele and Gaven, Daniel. 2010. Highly Episodic Fire and Erosion Regime Over the Past 2000 Years in the Siskiyou Mountains, Oregon.

Fire is a primary mode of natural disturbance in the forests of the Pacific Northwest. Increased fuel loads following fire suppression and the occurrence of several large and severe fires have led to the perception that in many areas there is a greatly increased risk of high-severity fire compared with presettlement forests. To reconstruct the variability of the fire regime in the Siskiyou Mountains, Oregon, we analyzed a 10-m, 2,000-y sediment core for charcoal, pollen, and sedimentological data. The record reveals a highly episodic pattern of fire in which 77% of the 68 charcoal peaks before Euro-American settlement cluster within nine distinct periods marked by a 15-y mean interval. The 11 largest charcoal peaks are significantly related to decadal-scale drought periods and are followed by pulses of minerogenic sediment suggestive of rapid sediment delivery. After logging in the 1950s, sediment load was increased fourfold compared with that from the most severe presettlement fire. Less severe fires, marked by smaller charcoal peaks and no sediment pulses, are not correlated significantly with drought periods. Pollen indicators of closed forests are consistent with fire-free periods of sufficient length to maintain dense forest and indicate a fire-triggered switch to more open conditions during the Medieval Climatic Anomaly. Our results indicate that over millennia fire was more episodic than revealed by nearby shorter tree-ring records and that recent severe fires have precedents during earlier drought episodes but also that sediment loads resulting from logging and road building have no precedent in earlier fire events.[1]

[1] Colombaroli, Daniele and Gaven, Daniel. 2010. Highly Episodic Fire and Erosion Regime Over the Past 2000 Years in the Siskiyou Mountains, Oregon. Proc Natl Acad SCI US. 2010 Nov 2: 107 (44): 18909-18914. 2010. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2973861/

Cruz, Miguel, Alexander, Martin, Dam, Jelmer, 2014. Using Modeled Surface and Crown Fire Behavior Characteristics to Evaluate Fuel Treatment Effectiveness: A Caution

Conclusions

As Cruz and Alexander (2010) have pointed out, the fuels management literature abounds with examples of so-called evaluations of fuel treatment effectiveness based on simulations performed using fire modeling systems and assumptions that may not be valid or are otherwise incomplete for various reasons as identified by Keyes and Varner (2006) and Varner and Keyes (2009). In this particular fire behavior modeling case study, the predicted fireline intensity, onset of crowning, and active crown fire spread were shown to vary widely depending on the assumptions used to estimate fuel dryness. Small changes in the estimated fine dead fuel moisture content (i.e., <2.5%) can produce widely varying results. This variation is especially relevant when models are used to evaluate the effects of silvicultural fuel treatments due to the effect of the changes in stand structure on the micrometeorological environment.

Cruz, Miguel, Alexander, Martin, Dam, Jelmer, 2014. Using Modeled Surface and Crown Fire Behavior Characteristics to Evaluate Fuel Treatment Effectiveness: A Caution. For. Sci. 60(5):1000 –1004 http://dx.doi.org/10.5849/forsci.13-719

DellaSala, Dominick A, Ingalsbee, Timothy, Hanson, Chad T, 2018. Everything You Wanted to Know About Wildland Fires in Forests but Were Afraid to Ask: Lessons Learned, Ways Forward, GEOS Institute Report.

Box 1. General limitations of thinning (and collateral ecosystem damages)
(1) Thinning reduces habitat for canopy dependent species, including spotted owls22, requires an expansive road network damaging to aquatics, can spread invasive and flammable weeds, and, when implemented over large landscapes, releases more carbon emissions than fires, even severe ones23.
(2) There is a very low probability (3-8%) that a thinned forest will encounter a fire during the narrow period (10-20 years depending on site factors) of reduced “fuels” 24, resulting in large-scale thinning proposals that alter forest conditions over large areas6. 
(3) Excessive thinning (e.g., reducing bulk crown density below 60%) can increase wind speeds and solar radiation to the ground causing increased flammable vegetation growth and fire spread. 
(4) Thinning needs to be followed by prescribed fire to reduce flammable slash but this can cause soil damage especially if burning is concentrated in piles (intensifies heat effects. 
(5) Thinning is seldom cost effective without public subsidies or removing large fire-resistant trees. 
(6) In some regions (Sierra, Klamath-Siskiyou), time since fire is not associated with increasing fire risks (i.e., as forests mature, they become less flammable25).
(7) Thinning efficacy is limited under extreme fire weather (principal factor governing large fires). 
(8) At regional scales, active management (unspecified forms of logging) have been associated with uncharacteristic levels of high severity fires (see figure below)26.

Conclusion: Moving Forward in the New Climate Wildfire Era

…

Based on climate change models, extreme fire conditions are predicted to be more common this century and thus the extensive thinning involved to theoretically reduce fire intensity (e.g., wide spacing among trees, open-park like conditions) would create novel or greatly engineered forest systems that impact biodiversity and ecosystem services (carbon stores, clean water) in undesirable ways.

…

Wildfire effects on vegetation are highly variable (mixed) [(Odion et al. 2016)] calling into question fuel reduction projects (especially those that use a shifting baseline) based on restoring forests to an “historical” open park-like condition when there was a lot more variability and the climate is changing.

It will be impossible to mechanically treat the substantial acres alleged to need fuel reduction to reduce fire intensity (58 million acres according to the Forest Service), and, even if possible, this would have severe consequences to ecosystems, especially aquatics, and come with substantial taxpayer funded costs.

Thinning under extreme fire weather (“the new norm”) is highly uncertain in a changing climate.[1]

[1] DellaSala et al. 2018. Everything You Wanted to Know About Wildland Fires in Forests But Were Afraid to Ask: Lessons Learned, Ways Forward, GEOS Institute Report.

In July 2015, twenty-five leading fire scientists from around the world, led by Chad Hanson and Dominick DellaSala, released a new book providing a global synthesis on large wildland fires called The Ecological Importance of Mixed Severity Fires: Nature’s Phoenix.

This synthesis provides for the first time, extensive documentation from around the world that reveals how forests and other plant communities need a variety of different types of fires, including severe ones, to rejuvenate over the long-term. These findings challenge and disprove the assumption that fires are damaging to forests, and logging and prescribed burning is needed to reduce fire effects.[1] It also presents important findings about how to protect communities at risk without resorting to drastic attempts to reduce “fuel.”

Researchers compiled findings from western North America, central Europe, southeast Australia, and sub-Saharan Africa, summarized as:

• Forest thinning in the backcountry does not improve homeowner safety, and does not meaningfully influence large, weather-driven fires.
  …

• People can live safely with fire in the backcountry by building with fire-resistant materials and reducing flammable vegetation nearest homes.
  …

• Record fire suppression is doing little to stop large fires during extreme weather events. It is best to prepare for fire by reducing risks to homes and proper zoning that limits sprawl into fire-prone areas.[2]

DellaSala added, "In the 1940s when the Forest Service started its fire suppression policy, it made sense to put out fires for public safety. The truth is, large fires are not going away no matter what we do to try to stop them, so we need to do a better job of investing scarce public resources in protecting lives and homes."[3]

This major fire reference includes nearly 400 pages of science-based accounts of large and severe fires that have shaped the ecology of plant and wildlife communities for millions of years. So called "mixed-severity fires" burn in a mosaic (quilt-like) pattern of small to large patches of low (ground burning) to high-severity (most trees killed) burns that resembles a living kaleidoscope of plants and wildlife. This is in stark contrast to logging after a fire.[4]

Chad Hanson, Ph.D., Director of the John Muir Project, research ecologist, and co-editor/co-author of the book, states, “Though the timber industry and Forest Service would like to keep the public afraid of fire in order to justify continued taxpayer-subsidized commercial logging on our national forests, the truth is that we do not need to be afraid of fire in our forests.” 

As a global change agent, fire has been around since the dawn of terrestrial plants some 400 million years ago. It acts in concert with climate by triggering dramatic changes in ecosystems that reverberate across landscapes over long time lines. Tree fire scars, charcoal sediments long buried in lake deposits, and the fossil record provide clues of fire’s indelible imprint.

Nearly every terrestrial biome and continent (except for polar regions) is influenced by fire to some degree; in some years, fires have been active across a significant proportion of the Earth’s terrestrial surface. (Figure 1). But fire is hardly uniform in its occurrence, intensity, or spatial patterns (Figure 2) as discussed throughout this book.

Interestingly, fire can be considered a self-directed force of nature, but humans have a questionable record in dealing with it: We try to subjugate (suppression) or dampen and homogenize it (most prescribed wildland fires), reduce its intensity via manipulation or removal of vegetation (fuels management), unknowingly build structures in its path, and willingly log the biologically rich postfire landscape, which results in many undesirable and unintended consequences. We are also changing the global climate in a way that could result in too much fire in some ecosystems and too little in others. For the large fires burning in fire-climate years (e.g., droughts), attempting to stop them over vast areas has proven risky to firefighters, costly, largely ineffective, and ecologically misinformed.”

…

Notably, fire severity is influenced by many factors, including slope (steep vs. gentle), aspect (cardinal direction of the slope), topographic position (low vs. higher elevations), fuels (vegetation), and weather (especially drought and high winds). In a mixed-severity fire, burn severity patterns are loosely influenced by the unequal effect of fuels and topography and are more directly governed by weather. For instance, in some regions low-severity patches within mixed-severity burns often occur along low-slope positions and on the northeast aspects (generally wetter or cooler areas), whereas high-severity patches tend to occur relatively more frequently on southwest and upper slopes and along ridgelines (generally hotter and more exposed areas; Agee 2005). This variability in fire severity patch patterns makes reconstructing fire histories for a particular area difficult; the patch mosaic shifts across the landscape from one fire to the next (dynamic) because of differences in weather and local fuel conditions (topographic influences remain constant). Notably, high-severity (crown) fires are frequently weather-driven events, with fuel being of secondary importance.[5]

The findings from this global synthesis show that “Contrary to what many think, large and severe fires are not currently increasing in western North America compared to historical times.”[1]

A commonly articulated hypothesis is that dry forests at low elevations in western North America were historically open and park-like, and heavily dominated by low-severity and low/moderate-severity fire (Weaver, 1943; Cooper, 1962; Covington, 2000; Agee and Skinner, 2005; Stephens and Ruth, 2005). Under this hypothesis, high-severity fire patches were rare, or at least were believed to be small to moderate in size, and larger patches (generally hundreds of hectares or larger) that burn today often are considered to be unnatural and ecologically harmful. While this model fits reasonably well in some low elevation, xeric forest systems (Perry et al., 2011; Williams and Baker (2012a, 2013), it has been extrapolated far beyond where it seems to apply best. That higher fire severities occurred historically, albeit at a wide variety of spatial and temporal scales, in  most or all fire-dependent vegetation types of western North America is becoming increasingly clear (Veblen and Lorenz, 1986, Mast et al., 1998; Taylor and Skinner, 1998; Brown et al., 1999; Kaufman et al., 2000; Heyerdahl et al., 2001, 2012; Wright and Agee, 2004; Sherriff and Veblen, 2006, 2007; Baker et al., 2007; Hessburg et al., 2007; Klenner et al., 2008; Amoroso et al., 2011; Perry et al., 2011; Shoennagel et al., 2011; Williams and Baker, 2012a; Marcoux et al., 2013; Odion et al., 2014; Hanson and Odion, 2015a).

A key extension of the concept of historical forests characterized by open structure coupled with a low- or low/moderate-severity fire regime is that current areas of dense forest structure—and larger, higher-severity fire patches in such areas—are the result of unnatural fuel accumulation from decades of fire suppression policies, leading to higher-severity fire effects outside the natural range of variability. The most fire-suppressed forests (i.e. those that have gone without fire for periods that exceed their “average” natural fire cycles) are, therefore, expected to experience unnaturally high proportions of higher-severity fire if they burn (Covington and Moore, 1994; Covington, 2000; Agee, 2002; Agee and Skinner, 2005; Stephens and Ruth, 2005; Roos and Swetnam, 2012; Williams, 2012; Stephens et al., 2013; Steel et al., 2015).

We recognize that the historical low-severity fire regime described above has not been applied to all forest types in western North America (e.g. Romme and Despain, 1989; Agee 1993). The idea has, however, been widely applied in principle to most forest types, and widespread acceptance of the low- and low/moderate-severity fire regime has been the primary basis driving fire management policy in an overwhelmingly large proportion of montane forests in the western United States. Thus many management plans explicitly adopt a low-severity fire regime model without rigorously examining evidence of its applicability to the management of the ecosystem type under consideration. A key research need has been to determine the particular ecosystem types to which the low-severity fire regime applies. Scientists recently rigorously investigated the hypothesis that forests are burning in a largely unnatural fashion and found that historical forest structure and fire regimes were far more variable than previously believed, and that ecosystem response to large, intense fires often differ from past assumptions (Figure 1.1; see also Chapters 2-5). We discuss these notions in greater depth throughout this book.

Do Open and Park-Like Structures Provide an Accurate Historical Baseline for Dry Forest Types in Western US Forests?

Using spatially extensive tree ring field data, historical landscape photography from the late 19th and early 20th centuries, early aerial photography from the 1930s through 1950s, and direct records from late 19th-century land surveyors, numerous recent studies have been able to reconstruct the historical structure of conifer forests in the western United States. A portion of the historical montane forest landscape in any given region undoubtedly comprised open forest dominated by low-severity fire (e.g., Brown et al., 1999, Fule et al. 2009, Iniguez et al., 2009; Perry et al., 2011; Williams and Baker, 2012a; Hagmann et al., 2013; Baker, 2014), and some forest types (e.g. ponderosa pine [Pinus ponderosa]) often had a preponderance of low-severity fire in many low-elevation or xeric-type forest environments throughout western North America. Nevertheless, landscape-level evidence indicated that vast forested areas also comprised moderate to very dense forests characterized by a mixed-severity fire regime, wherein higher-severity fire patches of varying sizes occurred in a mosaic of low- and moderate-severity fire effects (Veblen and Lorenz 1986, 1991; Baker et al. 2007; Sherriff and Veblen, 2007; Hessburg et al., 2007; Perry et al., 2011; Baker, 2012; Williams and Baker, 2012a,b; Baker, 2014; Baker and Williams, 2015; Hanson and Odion, 2015a). In general, in historical ponderosa pine and mixed-conifer forests of the western United States, local variability was substantial (Brown et al., 1999, Fule et al. 2009, Iniguez et al., 2009; Hessburg et al., 2007; Perry et al., 2011; Baker, 2012; Williams and Baker, 2012a,b, 2013; Baker, 2014; Baker and Williams, 2015; Hanson and Odion 2015a). In sum, these and other studies indicate that historically there was high variability in fire effects (low to high severity) and composition and structure at both small and large spatial scales, and these patterns varied greatly depending on the regional and biophysical setting.[6]

…

Does Time Since Fire Influence Fire Severity

The predominant view in North American fire science has been that as woody ecosystems age, they steadily increase in their potential for higher-severity fire. Thus in the fire exclusion/fuels buildup model applied to relatively dry conifer forests and woodlands (e.g., Covington and Moore, 1994), long fire-free intervals caused by effective fire suppression result in fuel accumulation and changes in fuel arrangements (e.g., vertical fuel continuity) that lead to increased fire severity. Likewise, even for forest ecosystems known to burn primarily in severe stand-replacing fires, many classical models of fire potential (in this case the instantaneous chance of fire occurrence) assume that fire severity increases with time since the last fire as a result of fuel accumulation (Johnson and Gutsell, 1994); some research support this (Steel et al., 2015). Nevertheless, empirical and modeling studies have demonstrated that in many ecosystem types, including temperate forests, flammability is still relatively stable with regard to time since fire (Kitzberger et al., 2012; Perry et al., 2012; Paritsis et al., 2014). We suggest that the predominance of the viewpoint in the western United States that flammability and potential fire severity inexorably increase with time since fire has been an important contributor to the expectation that 20th-century fire suppression—if assumed to have effectively reduced fire frequency—should result in increased, and unnaturally high, fire severity in the modern landscape. This relationship does not seem to hold in various ecosystem types and regions for a wide variety of reasons (Veblen, 2003; Odion et al., 2004; Baker, 2009; van Wagtendonk et al., 2012). But even if it held everywhere, this preoccupation with changes from historical proportions of higher-severity fire skirts the key management questions of whether a change in the proportion of higher-severity patches renders a forest incapable of “recover” after such fires (precious few papers deal with this key management question) or whether the overall spatiotemporal extent of higher-severity fire (i.e., rotation intervals) exceeds historical levels.

A second assumption about fire regimes in the western United States is implied by language commonly used to describe modern fire regimes in terms of “missed fire cycles.” While fire cycle may be a useful descriptor of fire regimes, the assertion that a particular place or patch has missed one or more fire cycles implies a regularity to fire return intervals that is not supported by most studies of fire history; there is always variation around a mean. Even in dry forests characterized by relatively frequent fires, the historical fire frequency is typically characterized by such a high degree of variance that descriptors such as means or cycles are misleading. Using the term missed fire cycle in mixed-severity fire regimes, among which the frequency and severity of fires are inherently diverse, is particularly problematic. Usage of missed fire cycles connotes a consistency and degree of equilibrium in the historical fire regime that is not supported by actual fire history evidence, which shows large variations in fire intervals (e.g., Baker and Ehle, 2001; Baker, 2012). Though it seems to make intuitive sense that, with increasing time fire, fuels would accumulate to create a higher probability of higher-severity fire effects, numerous countervailing factors modulate fire severity as stands mature since the previous fire.

Notably, many studies of this issue have found that, in some areas, the most long-unburned forests are burning mostly at low/moderate severity and are not experiences higher levels of high-severity fire than forests that have experienced less fire exclusion (Odion et al., 2004, 2010; Odion and Hanson, 2006, 2008; Miller et al., 2012; van Wagtendonk et al., 2012). Further, forests with the largest amounts of surface fuels (based on prefire measurements) and small trees do not necessarily always experience more severe fire (Azuma et al., 2004). Debate about this issue remains, however. For example, Steel et al. (2015, Table 7 in particular) modeled time since fire and fire severity in California’s forests and predicted that, in mixed-conifer forests, high-severity fire would range from 12% 10 years after fire to 20% 75 years after fire, though the modeling for mixed-conifer forests seems to have been based on what appears to be very limited data for forests that experienced fire less than 75 years earlier (Steel et al., Figure 4), weakening inferences about a time since fire/severity relationship. Regardless, the high-severity fire values reported by Steel et al.—even for forests that had not previously burned for 75-100 years—remain well within the range of natural variation of high-severity fire proportions in these forests found by most recent studies (Beaty and Taylor, 2001; Bekker and Taylor, 2001; Baker, 2014; Odion et al., 2014; Hanson and Odion, 2015a).

Although the notion that fire severity would not necessarily increase with time since fire is seemingly counterintuitive, a number of factors help explain it. For example, as forests mature with increasing time since the last fire, canopy cover increases, creating more cooling shade, facilitiating moister surface conditions, and slowing wind speeds and thus rates of fire spread. Also, increasing shade in the forest understory can cause a reduction in sun-dependent shrubs and understory trees, making it more difficult to initiate or sustain crown fire (Odion et al., 2004, 2010; Odion and Hanson, 2006). Much more important, however, is that severe fire events are largely driven by weather (Finney et al., 2003) and often have relatively little to do with the amount of fuel available (Azuma et al., 2004).[7]

[1] GEOS Institute 2015. “Global Synthesis of Large Wildland Fires Shows They Are Ecologically Beneficial”

http://www.prnewswire.com/news-releases/global-synthesis-of-large-wildland-fires-shows-they-are-ecologically-beneficial-300107497.html

[2] Id.

[3] Id.

[4] Id.

[5] DellaSala and Hanson, 2015 The Ecological Importance of Mixed Severity Fires: Nature’s Phoenix at Preface xxv-xxviii

[6] DellaSala and Hanson, 2015 “Setting the Stage for Mixed- and High-Severity Fire” from The Ecological Importance of Mixed Severity Fires: Nature’s Phoenix at 3-6.

[7] DellaSala and Hanson, 2015 “Setting the Stage for Mixed- and High-Severity Fire” from The Ecological Importance of Mixed Severity Fires: Nature’s Phoenix at 6-8.

DellaSala and Hanson 2019. Are Wildland Fires Increasing Large Patches of Complex Early Seral Forest Habitat?

High-severity fire creates patches of complex early seral forest (CESF) in mixed-severity fire complexes of the western USA. Some managers and researchers have expressed concerns that large high-severity patches are increasing and could adversely impact old forest extent or lead to type conversions. We used GIS databases for vegetation and fire severity to investigate trends in large (>400 ha) CESF patches in frequent-fire forests of the western USA, analyzing four equal time periods from 1984 to 2015. We detected a significant increase in the total area of large patches relative to the first time period only (1984–1991), but no significant upward trend since the early 1990s. There was no significant trend in the size of large CESF patches between 1984 and 2015. Fire rotation intervals for large CESF patches ranged from ~12 centuries to over 4000 years, depending on the region. Large CESF patches were highly heterogeneous, internally creating ample opportunities for fire-mediated biodiversity. Interior patch areas far removed from the nearest low/moderate-severity edges comprised a minor portion of high-severity patches but may be ecologically important in creating pockets of open forest. There was ample historical evidence of large CESF patches but no evidence of increases that might indicate a current risk of ecosystem-type shifts.[1]

[1] DellaSala and Hanson 2019. Are Wildland Fires Increasing Large Patches of Complex Early Seral Forest Habitat? Diversity 2019, 11, 157; doi:10.3390/d11090157

DellaSala, Dominick. 2017. Geos Institute Comments RE: Pickett West Forest Management Project Environmental Assessment and Draft Finding of No Significant Impact.  July 10, 2017

The EA erroneously presumes a continuous fuel buildup in fire-suppressed forests much like that of fire-suppressed open, dry ponderosa pine forests outside the region. Fire regimes and vegetation dynamics in the Klamath-Siskiyou are exceptionally varied (Halofsky et al. 2011). Fuel build up in the absence of fire does not necessarily increase fire severity as often claimed (Odion et al. 2004). Instead, fuel that is receptive to combustion may decrease in long absence of fire as forest canopies shade-out flammable understory vegetation. This actually favors the fire regime that mixed evergreen forests of the region have adapted to for millennia. We have attached a critique of a similar scientifically incredulous approach advocated by The Nature Conservancy parallels the BLM project (attachment). Please consider the issues raised in this attachment as directly comparable to this EA. I also have included the following comment on a similar BLM logging project evaluated in 2005 by Dr. Dennis Odion, a local fire ecology expert:

“In many temperate forests, the fuels that determine fire behavior may reach equilibrium (Gutsell et al. 2001, Johnson et al. 2001), decrease with long fire intervals (Romme 1982, Christensen 1991, Bond and van Wilgen 1996, Odion et al. 2004), or change in other ways that differ from continuous fuel build up (Agee and Huff 1987). A fundamental property of forests is that their leaf area reaches a maximum relatively early in succession (Waring and Schlesinger 1985), so foliar fuels, do not exhibit a continuous net increase. Understory trees in closed forests may not contain the leaf area (about 0.037 kg/m3) for propagating fire (Scott and Reinhart 2001), and so the presence of such trees due to fire suppression or other causes does not necessarily equate to build-up of fuel that helps propagate fire. The EA does not recognize any minimum level of foliar fuel necessary to vertically propagate fire in its use of the term “ladder fuel” and does not appear to factor this into its fire modeling. Conifer poles in closed forests typically have very sparse foliage and may not be significant propagators of fire. If they were, there would be much more high severity fire in long-unburned old-growth forests.”

Importantly, fire in old-growth forests is not an ecological catastrophe as often claimed. The complex early seral forest resulting from a severe fire in an old forest includes a rich array of “biological legacies” (Lindenmayer et al. 2002) rivaling the biodiversity of old-growth forests (Swanson et al. 2011, DellaSala et al. 2014). High quality complex early forests may be even less common than old growth because these forests are almost always logged post-fire, treated with herbicides, and replanted to densely stocked, flammable plantations by managers wishing to 3 truncate early forest succession (Lindenmayer et al. 2008, DellaSala et al. 2015). Proposed logging and prescribed fire also do not substitute for landscape heterogeneity of a natural mixedintensity fire event (Hanson et al. 2015) that is important to the fire ecology and biodiversity of this region (see Halofsky et al. 2011).

The EA also relies heavily on the assumption that the project area is outside natural range of variability due to fire suppression. However, Colombaroli and Gavin (2010) (attached) reconstructed fire regimes over a 2000-year period using sediment core samples of charcoal pollen in the nearby Upper Squaw Lake drainage. They found that over millennia, fire was:

§ Highly episodic;

§ Tracked decadal drought cycles;

§ Recent severe fires have precedents during earlier drought cycles (i.e., they are not unusual or atypical of the region); and

§ Today’s forests are resilient to even severe fires. The only factor that was outside historic bounds in their comprehensive study was increased sedimentation rates (novel) attributed to logging roads. Thus, restoration projects should include a transportation plan to deal with the adverse impacts of an extensive roads network that is a much higher threat to forest health than the natural mixed-intensity fires of the area.

Additionally, Baker (2011) submitted comments (attached) to the BLM previously that included an analysis of stand densities in the Middle Applegate Area based on the General Land Office Surveys (GLO). GLO data were used to reconstruct an historic baseline for comparisons to current stand densities. Baker found that tree densities varied substantially in the area historically, including some (emphasis added) open, low-density forests (<150 trees/ha) and many dense forests (150-350 trees/ha). Much of the landscape was not “open” as claimed. Similarly, DiPaolo and Hosten (2015) (attached) used homestead patent applications and associated land classification maps from 1907-1917 to reconstruct historic vegetation in the Applegate River watershed. They found that today’s conifer forests and shrublands along middle and lower slopes retained most of their former extents within the same locations on the landscape. This historic landscape, like current conditions, comprised a diversity of conifer structures, including dense pole stands, mature closed canopy Douglas-fir forests, some open pine stands, and disturbance-impacted stands with scattered older cohorts and abundant conifer regeneration, and/or dense shrub layers at low-mid elevations. Closed-canopy conifer forests and dense chaparral were historically dominant. Importantly, native grasslands and oak savanna that have recently declined were most often located in valley bottoms and were mostly lost to agricultural development, not fire suppression as is often surmised.

In closing, the BLM would better serve the Applegate community by proactively engaging in projects that reduce fire risks closest to home structures – that is working from the home-out instead of the wildlands-in (see Cohen et al. 2000, Schoenaggel et al. 2009, Syphard et al. 2012, Schoennaggel et al. 2017). A project of this magnitude, would result in cumulative impacts to the environment from:

§ Degradation of northern spotted owl habitat, owl prey, and loss of habitat of other late seral associates by substantial reductions (down to 30% canopy) in canopy closure that may further enable barred owl encroachment in spotted owl territories (Dugger et al. 2011);

§ Increased fuel loads due to on-site removal of fire-resistant trees, post-fire salvage logging, and type conversion to flammable plantations; and

§ Road-related fire risks, increased invasive species problems, and sediment problems from roads that degrade water quality.

Logging in the back-country away from homes will do nothing to improve home safety, and, in fact, may make landscapes more vulnerable to uncharacteristically severe fires by converting fire-resilient native forests to flammable plantations (Odion et al. 2004, Bradley et al. 2016). Opening up mature closed canopy forests closer in to homes will likely have adverse effects on fire safety in the WUI through the increase of fire spread and intensity.

…

Importantly, the EA unrealistically assumes thinning, without assessing the full range of potential outcomes, leads to reduced fire intensity. However, Rhodes and Baker (2008) showed that the probability of a thinned site encountering a moderate or high severity fire during an assumed 20-year period when fuels are low was only 2-7.9%. The efficacy of thinning during extreme fire-weather is also highly questionable (Cary et al. 2016) especially in a changing climate that may increasingly result in more extreme fire weather rendering thinning largely ineffective. For the reasons stated above, BLM needs to conduct a comprehensive Environmental Impact Statement, and not just an EA, as its decision to dismiss impacts as “non significant” is not based on best available science or a credible analysis of project-related cumulative impacts to the environment or the degree of controversy this project has elicited.[1]

[1] DellaSala, Dominick. 2017. Geos Institute Comments RE: Pickett West Forest Management Project Environmental Assessment and Draft Finding of No Significant Impact.  July 10, 2017

DellaSala, Dominick & Anthony, Robert, Bond, Monica, Fernandez, Erik, Frissel, Chris, Hanson, Chad, Spivak, Randi. 2013. Alternative Views of a Restoration Framework for Federal Forests in the Pacific Northwest.

3. Lack of Appropriate Baseline Compromises Restoration in Mixed-Severity Fire Regions

Franklin and Johnson’s (2012) approach to restoration focuses on commercial thinning to achieve desired conditions; however, for restoration to be ecologically based, foresters need an appropriate baseline from which to gauge the efficacy of restorative actions. For instance, under ecological forestry what does a restored site look like if not compared with an appropriate reference condition (e.g., comparable area of high ecological integrity) (DellaSala et al. 2003) or historical baseline? How will managers know when a site is restored, given the long time periods necessary to restore degraded sites? In particular, baseline studies in the Klamath-Siskiyou ecoregion have questioned dry fuel models that are being incorrectly applied to justify VRHs and thinning in BLM pilots. For example, fire regimes in this region are of mixed severity (DellaSala 2006, Halofsky et al. 2011) and are within historical bounds (Colombaroli and Gavin 2010),and open plant communities were of minor importance historically (Leiberg 1900, Duren et al. 2012). Hessburg et al. (2007) and Baker (2012) also demonstrated that small (16 dbh) trees were abundant historically and actually numerically dominant in forests east of the Cascades in Oregon and Washington and that open stands were less common than assumed. Thus, this lack of an appropriate baseline may result in approaches that appear restorative because they are based on presumed historical conditions but that incorrectly calibrate a forest stand against a baseline that instead represents significant departures from an earlier state not considered (Papworth et al. 2009) and that could lead to novel ecosystems (Figure 3). Novel ecosystems, systems that have been sufficiently altered in structure and function most often by human action, can favor nonnative species and flip ecosystem dynamics to altered states (Lindenmayer et al. 2011).The altered state may not be resilient to climate change because of accumulating land-use stressors, particularly from multiple stand entries that can compound the effects of ecological perturbations (Paine et al. 1998).

Franklin and Johnson (2012) and many managers assume that the absence of fire at the stand or landscape level constitutes an a priori risk due to a buildup of hazardous fuels in DFs. However, empirical studies have not shown this to be the case in the Klamath Siskiyou ecoregion (Odion et al. 2004, Halofsky et al. 2011) where fire severity declined as the time between fire return intervals increased (Odion et al. 2010). Thus, the more complex systematics and processes at play in regions of mixed-severity fires require precautionary principles that first define and then test assumptions about baselines before deciding on what desired future conditions should be, let alone the interventions necessary to attain them.[1]

…

7. Avoid creation of novel ecosystems by using both back casting (e.g., stand age reconstructions) and forecasting (e.g., downscaled climate change models) techniques to set restoration targets. We are not suggesting that ecosystems return to some specific past condition; however, clearly defined baselines with historical context or comparable reference areas of high ecological integrity should be a restoration prerequisite to avoid creation of novel ecosystems.[2]

[1] DellaSala, Dominick & Anthony, Robert, Bond, Monica, Fernandez, Erik, Frissel, Chris, Hanson, Chad, Spivak, Randi. 2013. Alternative Views of a Restoration Framework for Federal Forests in the Pacific Northwest.

[2] Id.

Dipaolo, Dominic and Paul Hosten. 2015. Vegetation Change Following The Forest Reserve Homestead Act Of 1906 In The Applegate River Watershed, Oregon.

Vegetation structure, composition, and community patterns on the landscape of southwest Oregon have changed since Euro-American settlement began in the mid-1800s. Much of this change has been attributed to the transition of land management strategies from those dominated by Native American practices, through the early Euro-American settlement period, and on to the post World War II era of industrial scale timber harvest and fire suppression. Using homestead patent applications and associated land classification maps generated under the Forest Reserve Homestead Act of June 11, 1906, we add to the understanding of historic vegetation conditions and evaluate vegetation change over time for land applied for by homesteaders in the Applegate River watershed of southwest Oregon. These homesteads were predominately located on areas now supporting chaparral, Pinus and/ or Quercus woodlands, mixed conifer forests, pastures, and agricultural land. Our study presents primary source documentation that describes stands dominated by broadleaf trees and shrubs as dense at the time of patent application, contrary to the assumption that such stand structures are an artifact of fire suppression efforts of the last century. Historic vegetation polygons cross tabulated with current classified imagery in GIS indicate that conifer forests and shrublands each retain most of their former extents within their same locations on the landscape. The persistence of shrub stands to current times implies longer-term stability of these communities and indicates that a transition to conifer domination is not evident in all shrublands.[1]

[1] Dipaolo, Dominic and Paul Hosten. 2015. Vegetation Change Following The Forest Reserve Homestead Act Of 1906 In The Applegate River Watershed, Oregon.

Duren, Olivia & Muir, Patricia, 2010. Does Fuels Management Accomplish Restoration in Southwest Oregon, USA, Chaparral? Insights from Age Structures.

Fuels management is often intended to both reduce fire hazard and restore ecosystems thought to be impacted by fire suppression.  Objectives to reduce fire hazard, however, are not compatible with restoration in many vegetation types.  Application of ecologically incompatible treatments to poorly understood ecosystems can drain management resources and contribute to ecosystem degradation.  Extensive areas of chaparral on Bureau of Land Management lands in southwest Oregon, USA, are annually targeted for fuels treatment.  However, the fire ecology of this ecosystem is not well understood and the assumptions guiding treatment need and design are based on extrapolations from other ecosystems.  We studied patterns in age structure of two obligate-seeding chaparral shrubs, sticky whiteleaf manzanita (Arctostaphylos viscida Parry) and buckbrush (Ceanothus cuneatus [Hook.] Nutt.) and assessed relationships with environment, fire, and potential livestock disturbance.  Results indicate that chaparral of obligate seeding species encompasses a wide range of structures and responses to environment and fire throughout its range.  While Mediterranean climate obligate-seeding shrub populations are typically even-aged, most stands unburned >30 yr were uneven-aged due to both recruitment in the absence of fire and to persistence of shrubs that predated the last fire.  Fire suppression does not seem to have altered chaparral structure or fire severity, and current fuels treatments appear unlikely to reproduce stand structures observed in mature chaparral or in post-wildfire stands.  Results underscore that effective fuels management should be both sensitive to regional variability and founded on ecosystem-specific data.[1]

[1] Duren, Olivia & Muir, Patricia, 2010. Does Fuels Management Accomplish Restoration in Southwest Oregon, USA, Chaparral? Insights from Age Structures.

Frost, Evan J. and Sweeney, Rob. 2000. Fire Regimes, Fire History and Forest Conditions in the Klamath- Siskiyou Region: An Overview and Synthesis of Knowledge

“The current popular and frequently repeated hypothesis about fires in the Klamath Mountains is that – as a result of fire suppression and other human activities – large fires are occurring more frequently and are larger and more intense than they were in the past (Atzet et al. 1988, USDA Forest Service 1994, 1995, 1996, 1998b, Brookes 1996). This position is predicated on assertions, that, because of fire suppression: 1) the number of fires in the region has declined over time, 2) fires are substantially larger today than in the past, and 3) large, intense fires are the results of unnaturally high levels of fuels accumulation. However, none of these assertions have been supported with empirical data from the Klamath Mountains or by analysis demonstrating that a change in fire frequency, size or severity has occurred from historic to present. If this hypothesis is not true, it may lead to inappropriate forest management and adverse impacts to regional biodiversity.”

“Lastly, it is important to recognize that the insights offered here represent a poorly developed “state of the art” because we currently have a very incomplete understanding of the role of fire in these forests, how this role has changed over time, and the most effectual means for restoring forests degraded by past management. There are significant risks associated with decisions made in the face of this high level of uncertainty. While ecosystem management plans will be developed in the absence of complete understanding, widespread application of highly intrusive treatments under the auspices of restoration could lead to further damage of the Klamath-Siskiyou region’s forest ecosystems.”[1]

[1] Frost, Evan J. and Sweeney, Rob. 2000 Fire Regimes, Fire History and Forest Conditions in the Klamath- Siskiyou Region: An Overview and Synthesis of Knowledge.

Hanson, Chad, Ph.D. 2010, The Myth of “Catastrophic” Wildfire: A New Ecological Paradigm of Forest Health

Executive Summary

Popular myths and misconceptions about the ecology of fire and dead trees in western U.S. conifer forests are numerous, and are strongly at odds with the recent scientific evidence, which indicates the following about these forest ecosystems:

>The only effective way to protect homes from wildland fire is to reduce the combustibility of the homes themselves, and reduce brush and very small trees within 100 feet of the homes. Commercial thinning projects that remove mature trees hundreds of yards – and often several miles – from the nearest home do not protect homes, and often put homes at greater risk by diverting scarce resources away from true home protection, by creating a false sense of security, and by removing large, fire-resistant trees and generating combustible logging “slash debris”, which increases potential fire severity. Currently, less than 3% of U.S. Forest Service “fuels reduction” projects are near homes.[1]

Page 17:

Even in dry ponderosa pine forests of the southwestern U.S., high-intensity fire naturally occurred prior to fire suppression and logging, with stand age plot data indicating historic high-intensity rotations of 300-400 years during the 1800s (Baker 2006).  The current high-intensity rotation is about 625 years in southwestern U.S. forests (Rhodes and Baker 2008).  Based on charcoal sediments, researchers have also determined that high-intensity fire was common in low-elevation ponderosa pine forests from about 1000 to 1400 A.D., contradicting the assumption that current high-intensity fire in such forests is uncharacteristic or unprecedented (Pierce et al. 2004, Whitlock et al. 2004).

Overall, the data indicate that there was about 2-4 times more high-intensity fire historically in western U.S. conifer forests than there is currently.  This fire deficit translates to serious deficits in ecologically-vital snag forest habitat, and this is greatly exacerbated by the fact that much of the snag forest habitat that is created by fire is lost to post-fire “salvage” logging.[1]

[1] Hanson, Chad, Ph.D. 2010, The Myth of “Catastrophic” Wildfire: A New Ecological Paradigm of Forest Health

Hutto, R., Bond, M., DellaSala, D. 2015. “Using Bird Ecology to Learn About the Benefits of Severe Fire,” Ecological Importance of Mixed-Severity Fires: Nature’s Phoenix. Chapter 3, p. 81.

What could we be doing differently? We need to trust that disturbance-dependent systems need severe disturbance (yes, that means a lot of tree death) to stimulate ecological succession in a manner that is indeed natural. We also need to appreciate that modeled means and standard deviations associated with measures of forest structure are not the same things as historical ranges of variation associated with the same measures. While some places have tree densities that exceed some estimated historical average value, it does not mean they fall outside the historical range of natural variation. Land managers need to relax in response to severe fire. As long as we can reduce the frequency of human-caused fires and remain safe during naturally ignited fire events, a management option that lets nature take its course will work just fine (Gill, 2001; Bradstock, 2008).  In this context, noting that safety is best achieved through mechanical treatments in small areas immediately adjacent to structures (Cohen, 2000; Cohen and Stratton, 2008; Winter et al., 2009; Stockmann et al., 2010; Gibbons et al., 2012; Syphard et al., 2014), and not through mechanical treatments in more remote wildlands, is important. Given this fact, why treatments in relatively remote, publicly owned wildlands have become the tactic most commonly used to reduce wildfire risk is puzzling (Schoennagel et al., 2009).

Concluding remarks

The most important ecological lessons we can take away from the bird research described in this chapter are that (1) many species have evolved to the point where they now require severe fire to create the conditions they need, and (2) even though some ecological systems may have departed significantly from what we believed to be historical conditions (e.g. tree plantations in the Pacific Northwest), birds are telling us (through their behavior and distribution patterns) that the vast majority of fire-dependent ecosystems are still well within the historical range of natural variation, are plenty “resilient,” and are fully capable of proceeding quite naturally through the process of succession following a severe-fire event. Therefore, thinning forests in the name of restoration is largely unnecessary. If this were not true, the world would be full of places that experienced a severe fire disturbance and then underwent an unnatural transformation or “type conversion” following the disturbance event, never to return to what was there before disturbance. It is most telling that those kinds of places are rare indeed.[1]

[1] Hutto, R., Bond, M., DellaSala, D. 2015. “Using Bird Ecology to Learn About the Benefits of Severe Fire,” Ecological Importance of Mixed-Severity Fires: Nature’s Phoenix. Chapter 3, pg 81

Johnson, E.; Miyanishi, K; Bridge, S.; 2001. Wildfire Regime in the Boreal Forest and the Idea of Fire Suppression and Fuel Buildup.

Unfortunately, this fuel-buildup idea has been uncritically and inappropriately applied to close-canopy ecosystems that have always had crown-fire regimes.

…

Conclusion

The idea of unnatural fuel buildup due to fire suppression causing a change in fire regimes has little support for closed-canopy ecosystems such as chaparral and boreal and subalpine forests.[1]

[1] Johnson, E.; Miyanishi, K; Bridge, S.; 2001. Wildfire Regime in the Boreal Forest and the Idea of Fire Suppression and Fuel Buildup.

Lesmeister et al. 2019. Mixed-severity wildfire and habitat of an old-forest obligate.

We found that the old-forest conditions associated with northern spotted owl habitat burned at lower severity despite having higher fuel loading than other forest types on the landscape. The microclimate and forest structure likely played a key role in lower fire severity in nesting/roosting habitat compared to other forest types. As succession progresses and canopy cover of shade-tolerant tree species increases, forests eventually gain old-growth characteristics and become less likely to burn because of higher relative humidity in soil and air, less heating of the forest floor due to shade, lower temperatures, lower wind speeds, and more compact litter layers (Countryman 1955, Chen et al. 1996, Kitzberger et al. 2012, Frey et al. 2016, Spies et al. 2018). In addition, as the herbaceous and shrub layer is reduced by shading from lower to mid-layer canopy trees, the connection between surface fuels and the canopy declines, despite possible increases in canopy layering (Halofsky et al. 2011, Odion et al. 2014). Alexander et al. (2006) found that in the Klamath-Siskiyou ecoregion, southern aspects tended to burn with greater severity, but exogenous factors also played an important role because areas with large trees burned less and had less fire damage than areas dominated by smaller trees. On the 2002 Biscuit Fire that burned near our study area, Thompson and Spies (2009) concluded that weather and pre-fire vegetation conditions were the primary determinants of crown damage. They found that forests with small-stature vegetation and areas of open tree canopies and dense shrubs experienced the highest levels of tree crown damage, while older, closed-canopy forests with high levels of large conifer cover were associated with the lowest levels of tree crown damage. The moisture content of air and soil in a forest affects the amount of fuel moisture, and thus the probability of ignition and burning temperature (Heyerdahl et al. 2001). In addition to the potential to mitigate negative effects of climate warming at local scales by creating refugia and enhancing biodiversity (Frey et al. 2016), we suggest that northern spotted owl nesting/roosting habitat also has the potential to function as fire refugia (i.e., areas with higher probability of escaping high-severity fire compared to other areas on landscape) in areas with mixed-severity fire regimes under most weather conditions. Thus, in these landscapes, management strategies to conserve old-growth characteristics may also reduce risk of high-severity wildfire (Bradley et al. 2016) and serve as buffer to negative effects of climate change (Betts et al. 2018).[1]

[1] Lesmeister et al. 2019. Mixed-severity wildfire and habitat of an old-forest obligate.

Lininger, Jay. 2004. Fire History and Need for Fuel Management in Mixed Douglas-Fir Forests Of The Klamath-Siskiyou Region, Northwest California And Southwest Oregon, USA.

Unmanaged forests tend toward wildfire resilience

A key feature of most unlogged mixed-conifer forests in the K-S region is the prevalence of very large (>20 inches in diameter), older trees that have survived numerous fires (Arno 2000, Frost and Sweeny 2000, Willis and Stuart 1994).  The structural diversity of unlogged mature forests in the form of high closed canopies and large down trees tend to inhibit hot fires (Agee and others 2000, DellaSala and Frost 2001). Shade provided by a closed forest canopy shields the ground surface from direct solar radiation, reduces ground temperature and increases the relative moisture of ground fuel (Countryman 1955).  Large down trees slow the horizontal movement of wind and thus, fire spread, and they store huge amounts of water that can take heat energy out of fire (Amaranthus and others 1989).  As noted above, unmanaged older forests are not immune from high severity, stand-replacing fires.  Indeed, some measure of high severity fire disturbance is an important influence on the biological diversity of K-S forests.

Young tree plantations are prone to severe fire effects

Wildfires often spread rapidly in young, even-age tree plantations due to contact with densely spaced fine fuels positioned low to the ground (DellaSala and others 1995, Sapsis and Brandow 1997).  Small trees in structurally homogenous stands have been anecdotally reported by fire fighters to vaporize when burned by wildfire (Ingalsbee 1997).  Young plantations are far more vulnerable to intense fire behavior and severe fire effects than unmanaged, closed canopy forests that retain higher levels of structural diversity, shading and moisture (Agee 1996, Odion and others in press, Weatherspoon and Skinner 1995).

…

3.  HISTORICAL ROLE OF FIRE IN KLAMATH-SISKIYOU FORESTS

Fire is the primary natural disturbance agent in K-S forests, influencing vegetation structure, species composition, soil properties, nutrient cycling, hydrology and other ecosystem processes (Agee 1993).  Most native plants and animals evolved with fire and many are adapted to, if not dependent on, fire’s periodic occurrence (Martin 1997).  Ecologists have suggested that the region’s outstanding biological diversity is due in part to its natural disturbance regimes and to fire in particular (Martin and Sapsis 1992).  Variability of fire regimes in time and space creates diverse complexes of species and habitats (Brown 2000).  It follows that conservation of ecological integrity depends on the extent to which managers allow fire to play its essential role in the ecosystem (Frost and Sweeny 2000).  Moreover, to be effective over the long-term, ecosystem management on federal lands must account for historic patterns of fire frequency, size, timing, intensity and severity in the design of appropriate restoration strategies (Baker 1994).  If land managers are to increase fire management activities, understanding the historic role of fire, its natural range of frequency and effects, and how these have changed due to human activities is essential to success (Hardy and Arno 1996).

3.1  Variability of fire occurrence and severity

Mixed-conifer forests of Douglas fir, white fir (Abies concolor), sugar pine (Pinus lambertiana), ponderosa pine (P. ponderosa) and incense cedar (Calocedrus decurrens) blanket the middle elevations of the Klamath Mountains and frequently intermix with forests consisting primarily of Douglas fir and hardwood species (Frost and Sweeny 2000) (figs. 2, 4).  The fire regimes of mixed-conifer and Douglas fir/hardwood forests are among the most variable in the Pacific Northwest, “prevent[ing] credible generalizations about fire and its ecological effects” (Agee 1993).  Historic and contemporary fires have included severe stand-replacing conflagrations, mixed severity fires, and low severity “underburns,” often within the same fire perimeter (Frost and Sweeny 2000).  As flames encounter different fuel conditions, topographic positions and weather, the intensity of fire and its effects on vegetation fluctuate in complex patterns.  The result is a patchy mosaic of multi-aged stands across the landscape, with each patch exhibiting different tree densities, ages and species (Taylor and Skinner 1998, Willis and Stuart 1994).

Time between fires (frequency) in mixed-conifer forests varies widely across the K-S, with documented return intervals ranging from 3 to 116 years.  In the Salmon River watershed, Willis and Stuart (1994) describe a mean frequency of 10 to 17 years, but with extreme variability (3 to 71 years) since 1740.  In the Thompson Creek watershed, Taylor and Skinner (1998) calculated median return intervals of 12 to19 years in four distinct plant associations.  Again, fire frequencies spanned significant ranges of time, from 4 to 87 years in stands consisting of white fir and Douglas fir, and from 5.5 to 116 years in pure stands of Douglas fir.

…

The development of forest stands exhibiting structurally diverse, late-successional conditions largely depends on the occurrence of relatively frequent and mixed-severity fires (Taylor and Skinner 1998). Variations of disturbance patterns in time and space are important to diversity in vegetative succession. This variability is likely a critical aspect of long-term ecosystem dynamics and function, and an important factor contributing to the K-S region’s outstanding biological diversity (Brown 2000, Martin and Sapsis 1992). Moreover, the wide variation in fire regime attributes likely is equally or more important than mean or median values in creating the vegetation mosaics that exist across the landscape (Frost and Sweeny 2000, Taylor and Skinner 1998).

…

4.3 Timber management has altered landscape flammability

At a landscape scale, selective logging has removed many of the large, fire-resistant trees that survived numerous fires (Arno 2000).  Clearcutting accelerated after the 1950s and has since converted tens of thousands of acres of mature and old growth forests into young, even-aged tree plantations (fig. 8) (Noss and Strittholt 1999).  Plantations are more susceptible to severe fire effects than unmanaged older forests (DellaSala and others 1995, Ingalsbee 1997, Odion and others in press).  The increased susceptibility of plantations to severe fire is due to:

• Structural characteristics including high stocking densities and uniform canopies that support heat energy output by fire (Sapsis and Brandow 1997).

• Warmer, windier and drier microclimates than unmanaged, closed canopy forests (Countryman 1955, van Wagtendonk 1996).

• Accumulations of fine logging “slash” on the ground that rarely get cleaned up (USDA 1994, Weatherspoon and Skinner 1995).

The number and distribution of plantations resulting from industrial timber management likely has altered fire behavior and effects at both stand and landscape scales (Frost and Sweeny 2000).  Perry (1995) suggests that the existence of highly combustible even-age tree patches on a forest landscape creates the potential for “a self-reinforcing cycle of catastrophic fires.”  In addition, most plantations occur next to roads that spread invasive and exotic plants (DellaSala and Frost 2001), and roads increase the risk of human-caused ignitions during hot, dry conditions (USDA 2000).

…

However, contemporary fires are not necessarily more severe than ever before due to fire exclusion. Industrial timber management likely has had greater direct, indirect and cumulative effects on fire severity patterns than fire exclusion due to the creation of dense networks of young tree plantations and roads. In contrast, areas without roads (fig. 9) generally displayed a higher proportion of low and moderate severity fire effects in the Klamath complex consistent with historical patterns (Odion and others in press).  The region’s relatively abundant roadless country is not easily accessible to fire suppression resources.  Therefore, a policy of fire suppression does not equate to effective fire exclusion in these areas (DellaSala and Frost 2001).

…

5.  IMPLICATIONS FOR FUEL MANAGEMENT

Extreme variation in climate, topography and vegetation of the K-S region compared to other regions preclude credible generalizations about fire history and effects in local mixed conifer forests dominated by Douglas fir.  Research specific to this region does not support the contention that fire regimes are significantly changed from the historic range of variability as a result of fire exclusion.  Indeed, strong evidence suggests that contemporary fires display severity patterns consistent with historic fire disturbances. The relatively short duration of effective fire suppression in some areas (50 to 60 years) coupled with wide natural variation in fire return intervals (3 to 116 years) argue against application of the “unnatural fuel buildup” hypothesis to K-S forests.

The idea that unnatural fuel accumulation has resulted from fire exclusion may apply to certain ponderosa pine forests of the Intermountain West, where low intensity surface fires historically maintained open forests which have now become prone to crown fires because of changes in fuel loading and arrangement in the absence of fire (Covington 2000, Hann et al. 1997).  However, this view of ecological change is subject to uncertainty because fire history methods lack modern calibration and are subject to sampling biases that rarely are taken into account (Baker and Ehle 2002).  There is little or no evidence to support its application to other ecosystems (Anderson et al. 1999), including K-S forests.  Nevertheless, federal land managers widely and unscientifically apply it (USDA 1998a, 1998b, 1998c, 1998d, USDI 2003, 2002a, 2002b, 1999). Ecologists have demanded convincing evidence of unprecedented conditions before land managers embark on evolutionarily unprecedented treatments such as intensive mechanical thinning to reduce fuel loads (Gutsell et al. 2001).

The need for intensive thinning to reduce fuel loading on K-S forest landscapes requires rigorous scientific assessment.  A widely used system for describing fire regimes and condition classes indicates that most of the K-S region is “moderately” or “significantly altered” from historic conditions and at-risk of “losing key ecosystem components” without fuel hazard mitigation (Schmidt and others 2000), and this system is cited in legislation that would greatly accelerate intensive thinning in K-S forests.  However, the “Fuelman” spatial data system’s reliability beyond providing a basis for prioritizing allocation of resources to local areas for further assessment is suspect.  It represents only the percentage of forested area and tree canopy cover, rather than actual forest structure or ground fuel loading, which is a prerequisite for predicting the likelihood of an active crown fire (DeBano and others 1998).  Thus, it does not provide a defensible basis on which to prioritize and design site-specific projects.  Attempts to base local fuel management planning on this system could result in misplaced projects and considerable waste of public resources (Morton 2003).

Such an assessment, at a minimum, should determine 1) areas where fire regimes have departed from the historic range of variability and where fire effects could be ecologically detrimental, 2) the most effective ways to mitigate fire effects where remedial action may be needed, and 3) ways to protect the region’s unique biological diversity from unnecessary degradation.  Systematic inventories of plant associations, fire history, forest structure and fuel loading are needed at a local scale to prioritize areas for fuel management. In addition, the following principles that emerge from existing knowledge about fire disturbance dynamics and forest development patterns in the K-S region should inform local risk assessment and project planning.[1]

[1] Lininger, Jay. 2004. Fire History and Need For Fuel Management In Mixed Douglas-Fir Forests Of The Klamath-Siskiyou Region, Northwest California And Southwest Oregon, USA.

Meigs, Garrett, Dunn, Christopher, Parks, Sean A., Krawchuk, Meg. 2020. Influence of topography and fuels on fire refugia probability under varying fire weather in forests of the US Pacific Northwest.

Fire refugia — locations that burn less severely or less frequently than surrounding areas — support late-successional and old-growth forest structure and function. This study investigates the influence of topography and fuels on the probability of forest fire refugia under varying fire weather conditions. We focused on recent large fires in Oregon and Washington, United States (n = 39 fires > 400 ha, 2004–2014). Our objectives were to (1) map fire refugia as a component of the burn severity gradient, (2) quantify the predictability of fire refugia as a function of prefire fuels and topography under moderate and high fire weather conditions, and (3) map the conditional probability of fire refugia to illustrate their spatial patterns in old-growth forests. Fire refugia exhibited higher predictability under relatively moderate fire weather conditions. Prefire live fuels were strong predictors of fire refugia, with higher refugia probability in forests with higher prefire biomass. In addition, fire refugia probability was higher in topographic settings with relatively northern aspects, steep catchment slopes, and concave topographic positions. Conditional probability maps revealed consistently higher fire refugia probability under moderate versus high fire weather scenarios. Results from this study inform conservation planning by determining late-successional forests most likely to persist as fire refugia despite increasing regional fire activity

               …

In western Oregon, Washington, and Northern California, old forests occupy a small portion of their historical extent because of widespread timber harvest, underscoring the significance of their unique structural features, including large, old trees and complex forest architecture, which provide habitat for threatened and endangered flora and fauna (Davis et al. 2016). In the PNW, old-forest habitats have been the focus of intensive public interest and conservation planning, most notably with the implementation of the Northwest Forest Plan (NWFP) (Spies et al. 2018; Stephens et al. 2019). Despite a general cessation of old-forest harvest on federal land since 1994, these forests have recently experienced widespread fire activity (Davis et al. 2017; Reilly et al. 2017), underscoring the urgency of understanding factors conducive to old-forest persistence (i.e., as fire refugia). The few studies that have explicitly assessed old-forest fire refugia in the PNW suggest that refugia are associated with specific topographic and vegetation (fuel) conditions (Camp et al. 1997; Kolden et al. 2017; Meigs and Krawchuk 2018; Lesmeister et al. 2019). Despite concerns about fire effects on late-successional forest habitats, species, and ecosystem services (Camp et al. 1997; Davis et al. 2016), fire refugia in old forests have not been mapped and evaluated across numerous large fire events in the PNW region.

…

This study assesses fire events in the West Cascades ecoregion, which contains a substantial amount of old forests and is located centrally within the PNW region.

…

We found that fire refugia predictability is related to multiple metrics of prefire live fuels and topography and that fire refugia probability is lower under higher fire weather conditions. Specifically, we determined that high-biomass forests on northwest-facing slopes have the highest refugial capacity, even when burning during periods of relatively high fire weather.[1]

[1] Meigs, Garrett, Dunn, Christopher, Parks, Sean A., Krawchuk, Meg. 2020. Influence of topography and fuels on fire refugia probability under varying fire weather in forests of the US Pacific Northwest. Can. J. For. Res. 00: 1–12 (0000) dx.doi.org/10.1139/cjfr-2019-0406

Mitchell, Stephen & Harmon, Mark & O’Connell, Kari. (2009). Forest fuel reduction alters fire severity and long-term carbon storage in three Pacific Northwest ecosystems. Ecological Applications.19. 643-55. 10.1890/08-0501.1.

[E]cosystems with lengthy fire return intervals, such as those of the west Cascades and Coast Range, may not be strongly altered by such a policy, as many stands would not have accumulated uncharacteristic levels of fuel during a time of fire suppression that is substantially less than the mean fire return intervals for these systems. Forests such as these may actually have little or no need for fuel reduction due to their lengthy fire return intervals. Furthermore, fire severity in many forests may be more a function of severe weather events rather than fuel accumulation (Bessie and Johnson 1995, Brown et al. 2004, Schoennagel et al. 2004). Thus, the application of fuel reduction treatments such as understory removal is thought to be unnecessary in such forests and may provide only limited effectiveness (Agee and Huff 1986, Brown et al. 2004). Our results provide additional support for this notion, as they show a minimal effect of understory removal on expected fire severity in these forests, and if in fact climate has far stronger control over fire severity in these forests than fuel abundance, then the small reductions in expected fire severity that we have modeled for these fuel reduction treatments may be even smaller in reality.

We also note that the extent to which fuel reductions in these forests can result in a reduction in fire severity during the extreme climate conditions that lead to broad-scale catastrophic wildfires may be different from the effects shown by our modeling results, and are likely to be an area of significant uncertainty. Fuel reductions, especially overstory thinning treatments, can increase air temperatures near the ground and wind speeds throughout the forest canopy (van Wagtendonk 1996, Agee and Skinner 2005), potentially leading to an increase in fire severity that cannot be accounted for within our particular fire model. In addition to the microclimatic changes that may follow an overstory thinning, logging residues may be present on site following such a procedure, and may potentially nullify the effects of the fuel reduction treatment or may even lead to an increase in fire severity (Stephens 1998). Field-based increases in fire-severity that occur in stands subjected to overstory thinning may in fact be an interaction between the fine fuels created by the thinning treatment and the accompanying changes in forest microclimate. These microclimate changes may lead to drier fuels and allow higher wind speeds throughout the stand (Raymond and Peterson 2005). While our model does incorporate the creation of logging residue that follows silvicultural thinning, increases in fire spread and intensity due to interactions between fine fuels and increased wind speed are neglected. However, we note that even if our model is failing to capture these dynamics, our general conclusion that fuel reduction results in a decrease in long-term C storage would then have even stronger support, since the fuel reduction would have caused C loss from the removal of biomass while also increasing the amount that is lost in a wildfire.[1]

[1] Mitchell, Stephen & Harmon, Mark & O’Connell, Kari. (2009). Forest fuel reduction alters fire severity and long-term carbon storage in three Pacific Northwest ecosystems. Ecological Applications.19. 643-55. 10.1890/08-0501.1.

Odion et al (2004) studied fire in the Klamath Mountains region and found:  Long absence of fire predicts low severity fire effects. Absence of fire enables closed canopy forest vegetation to replace shrub and open forest vegetation through succession. Shade reduces available fuel below the canopy as well as its potential surface heat output during fire events, making canopy fires less likely to occur. Therefore, severe fire effects are not correlated with the age of woody fuels. Instead, weather and climate dictate canopy fire behavior in closed canopy forests.[1]

Odion, D.C., E.J. Frost, J.R. Strittholt, H. Jiang, D.A. DellaSala and M.A. Moritz. 2004. Patterns of fire severity and forest conditions in the western Klamath Mountains, California.

We found (1) a trend of increasing fire size in recent decades; (2) that overall fire-severity proportions were 59% low, 29% moderate, and 12% high, which is comparable to both contemporary and historic fires in the region; (3) that multiaged, closed  forests, the predominant vegetation, burned with much lower severity than did open forest and shrubby nonforest vegetation; (4) that considerably less high-severity fire occurred where fire had previously be absent since 1920 in closed forests compared to where forests had burned since 1920 (7% vs. 16%); (5) that nonforest vegetation burned with greater severity where there was a history of fire since 1920 and in roaded areas; and (6) that tree plantations experienced twice as much severe fire as multi-aged forests. We concluded that fuel buildup in the absence of fire in the absence of fire did not cause increased fire severity as hypothesized. Instead, fuel that is receptive to combustion may decrease in the long absence of fire in the closed forests of our study area, which will favor the fire regime that has maintained these forests. However, plantations are now found in one-third of the roaded landscape. Together with warming climate, this may increase the size and severity of future fires, favoring further establishment of structurally and biologically simple plantations.[2]

[1] Odion, D.C., E.J. Frost, J.R. Strittholt, H. Jiang, D.A. DellaSala and M.A. Moritz. 2004. Patterns of fire severity and forest conditions in the western Klamath Mountains, California. Conservation Biology 18(4): 927-936. http://nature.berkeley.edu/moritzlab/docs/Odion_etal_2004.pdf.

[2] Id.

A study published in 2014 by the high-profile science journal PLOS ONE, an article, titled “Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America”, was co-authored by 11 scientists from various regions of the western US and Canada. Their study found that there is extensive evidence from multiple data sources that big, intense forest fires were a natural part of ponderosa pine and mixed-conifer ecosystems prior to modern fire suppression. These findings refute the claims frequently made by logging and biomass advocates that modern mixed-severity forest fires (erroneously called “catastrophic” fires) are an unnatural aberration that should be prevented through more logging (“thinning”) and that more biomass facilities should be built to take the resulting material from the forest. In contrast to these claims, logging done ostensibly to reduce fire severity now appears to be not only unnecessary, but also potentially detrimental when it is based on erroneous notions about historic forest conditions and fire regimes.

Abstract
There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to “restore” forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.[1]

[1] Odion et al. 2014. “Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America”  PLoS ONE 9(2): e87852. https://doi.org/10.1371/journal.pone.0087852

Odion, Dennis C. 2004. Comments on the Biscuit Post-Fire Logging Draft Environmental Impact Statement.

“However, all fire history studies that have been done in the region, based on scarred trees, have found a wide range in fire intervals, long fire free periods, and that the range in fire intervals is a more important property than the mean (summarized by Frost and Sweeney 2000). Agee (1991) found a pre-settlement fire free period greater than 100 years at nearby Oregon Caves. Over time scales beyond the last few centuries, there has not been any stationary amount of charcoal accumulation (Mohr et al. 2000), a measure of fire’s importance on the landscape over time. Fire has been both more and less common over meaningful time scales compared to recent centuries; there is no average tendency because of climatic variability. The description of historic fire intervals in the DEIS needs to be rewritten to accurately reflect high variability and non-equilibrium tendencies. These properties are associated with high levels of biodiversity (Odion et al. In Press).

The Tree-based fire history studies have ignored the longest fire intervals experienced by most trees, the one prior to the first fire scar on sampled trees, which can only be estimated (Baker and Ehle 2001). These fire history studies also use methods that extrapolate fire from a point location across space, which further over estimates fire frequency. Finally, areas sampled in fire scar studies cannot be assumed to represent the entire landscape; they are the locations where fire has operated in a way that has allowed for concentrations of trees scarred by low severity fires to develop. These may be unique locations where lightning and human ignitions were frequent, and fire size small.” ... “Most importantly the DEIS rationalizes timber harvest as a means to return a regime of relatively frequent fire at regular intervals. This fire regime would be unnatural, and would not allow for the landscape diversity that has existed historically [emphasis added].”

Odion, Dennis C. 2005.  RE: Environmental Assessment for the South Deer Landscape Management Project (EA# OR110-05-10). August 6, 2005

Old growth forests often dampen the spread and intensity of fire (Countryman 1955, Perry 1995). Without providing any empirical evidence, the EA presumes otherwise, a significant misconception. Low elevation, long-unburned Douglas-fir/hardwood forests like those of the project area are forest types that are experiencing very little high severity fire (Odion et al. 2004a-b, Azuma et al. 2004). Fire in these moist, old-growth forests is having beneficial effects of restoring its past influence, and there is not evidence that too much fire disturbance from an ecological standpoint can be expected. In fact, after a long period of reduced fire influence, fires that decrease stand density and create patchy landscape structure, may be most beneficial and best for expediting restoration (Miller and Urban 2000; Fule´ et al. 2004). Early successional habitat created by fire, with its rich array of snags and shrub vegetation is particularly important and rare habitat (Lindenmayer and Franklin 2002). The idea conveyed in the EA, that fire during the normal fire season in old-growth forests would be detrimental is misleading.

The proposed timber harvest and management burns would not have the restorative and heterogeneous effects of a natural fire. As required under NEPA, the agency should take a hard look at relevant scientific data on fire behavior and beneficial effects of natural fire. It makes no sense to presume old-growth forests should be cut down and replaced by combustible plantations when old-growth forests burn infrequently with complexity that favors biodiversity.

The EA also needs to take a scientific look at fuel dynamics in closed wet temperate forests rather than presuming continuous fuel buildup like that found in formerly open, dry ponderosa pine forests. In many temperate forests, the fuels that determine fire behavior may reach equilibrium (Gutsell et al. 2001, Johnson et al. 2001), decrease with long fire intervals (Romme 1982, Christensen 1991, Bond and van Wilgen 1996, Odion et al. 2004a-b), or change in other ways that differ from continuous fuel build up (Agee and Huff 1987). A fundamental property of forests is that their leaf area reaches a maximum relatively early in succession (Waring and Schlesinger 1985), so foliar fuels, do not exhibit a continuous net increase. Understory trees in closed forests may not contain the leaf area (about 0.037 kg/m3) for propagating fire (Scott and Reinhart 2001), and so the presence of such trees due to fire suppression or other causes does not necessarily equate to build-up of fuel that helps propagate fire. The EA does not recognize any minimum level of foliar fuel necessary to vertically propagate fire in its use of the term “ladder fuel” and does not appear to factor this into its fire modeling. Conifer poles in closed forests typically have very sparse foliage and may not be significant propagators of fire. If they were, there would be much more high severity fire in long-unburned old-growth forests.

The EA relies heavily on a hypothesis that the project area is outside the natural range of variability due to fire suppression actions, citing a publication by Thomas and Agee (1986). This publication is about prescribed burning at Crater Lake. In a more relevant publication based on research not far from the project area, at Oregon Caves, Agee (1991) could find no evidence of fire in recent centuries during a period of 100 years. This may be a longer fire interval than currently exists in much of the project area today considering that fire suppression did not become effective in many areas of the Klamath-Siskiyou region until the 1940’s. Given the potential for 100 year or more natural fire intervals, and the limitations of trying to estimate the past influence of fire on a heterogeneous landscape using fire scar analysis, which appear to significantly underestimation fire free intervals over whole landscapes (Minnich et al. 2000, Baker and Ehle 2001, Veblen 2003), the hypothesis that the project area is all outside the natural range of variation from recent centuries due to fire suppression may be incorrect. Complicating matters is the non-equilibrium nature of fire’s influence. It has changed constantly throughout the Holocene in the Klamath region (Whitlock et al. 2003), so it is impossible to know the natural range of variation in fire with just estimates from recent centuries when conditions were different than both prior to this and now.

On the other hand, areas where significant timber harvest occurs are indisputably outside any natural range of variation, with numerous stumps, exotic species and other altered forest structure, function and composition. Despite the concern expressed in the EA over unnatural conditions, the South Deer Landscape project proposes actions to create more area far outside any natural range of variability.

The EA also fails to adequately address the impacts of proposed burning. Native organisms have not evolved with deliberate burning, as it is typically applied in our region. This may involve pile burning, which sterilizes patches of soil, which then become prone to invasion by exotic species (Korb et al. 2004). The prolonged combustion and soil heating under a burn pile does not occur over an entire burned area as presumed in the EA (118), these effects are restricted to large, human created piles of surface fuel that do not occur in natural forests. Prescribed burning is also typically done during spring or after fall rain. Fires at this time do not produce the natural range of severities and other natural fire effects (Moritz and Odion 2004). These fires are lethal to numerous organisms that survive fire during the regular fire season, such as soil stored seeds that become seasonally sensitive (Borchert and Odion 1995). Nesting birds and dormant herptofauna may be adversely affected. Finally, out of season burns can lead to increase fuel loading (Show and Kotok 1924). Plant tissue is unusually sensitive to heat during the wet season, when tissue moisture content is high. Out of season broadcast burning causes much foliar mortality while often consuming very little surface fuel. [1]

[1] Odion, Dennis C. 2005.  RE: Environmental Assessment for the South Deer Landscape Management Project (EA# OR110-05-10). August 6, 2005

Raymond, Crystal (2004) The Effects of Fuel Treatments on Fire Severity in a Mixed-Evergreen Forest of Southwestern Oregon

“A greater percentage of pre-fire fine wood was consumed in the thinned plots than in the unthinned plots during the Biscuit fire suggesting that fine fuel moisture may have been lower in the thinned plots.” And “the Biscuit Fire was observed to have more moderate fire behavior in stands with a sub-canopy tree layer compared to more open stands, suggesting that the sub-canopy trees did not function as ladder fuels. … Higher foliar moisture of broad-leaved species could have dampened fire behavior, inhibiting rather than aiding crown fire initiation.”[3]

[3] Crystal L. Raymond. 2004. The Effects of Fuel Treatments on Fire Severity in a Mixed-Evergreen Forest of Southwestern Oregon. MS Thesis. http://depts.washington.edu/nwfire/publication/Raymond_2004.pdf.

Zald, H. and Dunn, C., 2018. Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape.

Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi-owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting management objectives, providing a unique experimental landscape to understand how different management practices influence wildfire severity. Leveraging Landsat based estimates of fire severity (Relative differenced Normalized Burn Ratio, RdNBR) and geospatial data on fire progression, weather, topography, pre-fire forest conditions, and land ownership, we asked (1) what is the relative importance of different variables driving fire severity, and (2) is intensive plantation forestry associated with higher fire severity? Using Random Forest ensemble machine learning, we found daily fire weather was the most important predictor of fire severity, followed by stand age and ownership, followed by topographic features. Estimates of pre-fire forest biomass were not an important predictor of fire severity. Adjusting for all other predictor variables in a general least squares model incorporating spatial autocorrelation, mean predicted RdNBR was higher on private industrial forests (RdNBR 521.85  18.67 [mean  SE]) vs. BLM forests (398.87  18.23) with a much greater proportion of older forests. Our findings suggest intensive plantation forestry characterized by young forests and spatially homogenized fuels, rather than pre-fire biomass, were significant drivers of wildfire severity. This has implications for perceptions of wildfire risk, shared fire management responsibilities, and developing fire resilience for multiple objectives in multi-owner landscapes.

…

Quantifying fire severity in the unique checkerboard landscape of the O&C Lands, this study disentangled the effects of forest management, weather, topography, and biomass on fire severity that are often spatially confounded. We found daily fire weather was the most important predictor of fire severity, but ownership, forest age, and topography were also important. After accounting for fire weather, topography, stand age, and pre-fire biomass, intensively managed private industrial forests burned at higher severity than older federal forests managed by the BLM. Below we discuss how the different variables in our analysis may influence fire severity, and argue that younger forests with spatially homogenized continuous fuel arrangements, rather than absolute biomass, was a significant driver of wildfire severity. The geospatial data available for our analyses was robust and comprehensive, covering two components of the fire behavior triangle (i.e., topography, weather), with pre-fire biomass and age serving as proxies for the third (fuel). However, we recognize there are limitations to our data and analyses and describe these below. We conclude by suggesting how our findings have important implications for forest and fire management in multi-owner landscapes, while posing important new questions that arise from our findings.[1]

[1] Zald, H. and Dunn, C., 2018. Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape. Ecological Applications, 0(0), 2018, pp. 1–13

216 Scientists 2018 Open Letter to Decision Makers Concerning Wildfire in the West,

Post-disturbance Salvage Logging Reduces Forest Resilience and Can Raise Fire Hazards – Commonly practiced after natural disturbances (such as fire or beetle activity), post-disturbance clearcut logging hinders forest resilience by compacting soils, killing natural regeneration of conifer seedlings and shrubs associated with forest renewal, increases fine fuels from slash left on the ground that aids the spread of fire, removes the most fire-resistant large live and dead trees, and degrades fish and wildlife habitat.13 Roads, even “temporary ones,” trigger widespread water quality problems from sediment loading. Forests that have received this type of active management typically burn more severely in forest fires.13

Wilderness and Other Protected Areas Are Not Especially Fire Prone – Proposals to remove environmental protections to increase logging for wildfire concerns are misinformed. For instance, scientists14 recently examined the severity of 1,500 forest fires affecting over 23 million acres during the past four decades in 11 western states. They found fires burned more severely in previously logged areas, while fires burned in natural fire mosaic patterns of low, moderate and high severity, in wilderness, parks, and roadless areas, thereby, maintaining resilient forests. Consequently, there is no legitimate reason for weakening environmental safeguards to curtail fires nor will such measures protect communities.[1] 

[1] 216 Scientists 2018 Open Letter to Decision Makers Concerning Wildfire in the West