Thomas A. Spies’s research while affiliated with Pacific Northwest Research Institute and other places

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Publications (200)


Historical Pyrodiversity in Douglas-Fir Forests of the Southern Cascades of Oregon, USA
  • Preprint

January 2024

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25 Reads

Andrew Merschel

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Thomas A. Spies

Jones et al. 2022 - WebTable1
  • Data
  • File available

September 2022

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126 Reads

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Thomas A. Spies

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Web Table 1. To Jones et al 2022.

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Counteracting wildfire misinformation

September 2022

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900 Reads

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17 Citations

Recent intense fire seasons in Australia, Borneo, South America, Africa, Siberia, and western North America have displaced large numbers of people, burned tens of millions of hectares, and generated societal urgency to address the wildfire problem (Bowman et al. 2020). Nearly all terrestrial ecosystems, however, burn with some degree of regularity, timing, and intensity; fire is a natural process. Wildfires are strongly influenced by climate and weather, which in turn shape the availability and flammability of fuels (Abatzoglou and Williams 2016). Yet rapid climate change is interacting with land-use legacies (eg fire suppression), transforming both wildfire and ecosystems (Coop et al. 2020; Hagmann et al. 2021). Like misinformation about climate, misinformation about wildfire has flourished in the media and in political discourse. Misinformation is incorrect or misleading evidence or discourse that counters best available science or expert consensus on a topic (Vraga and Bode 2020). Vulnerability to misinformation is often driven by distrust in media and institutions, and exacerbated by rapid spread over social media. By obstructing solutions to public health (eg COVID-19, childhood immunizations, tobacco use) and environmental issues (eg climate change), misinformation deters effective policy responses to societal threats.


Fire Ecology and Management in Pacific Northwest Forests

October 2021

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686 Reads

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19 Citations

Fire has been an important catalyst of change in Pacific Northwest forests throughout the Holocene. The role of fire varied across this biophysically diverse region prior to European colonization, but fire exclusion and logging drastically altered forest conditions during the 19th and 20th centuries. Despite recent increases in area burned and several large wildfires with devastating social and economic consequences, area burned in recent decades remains far less than under historical regimes across most of the region. Some dry forest landscapes have experienced profound change through uncharacteristically severe fires. In moist and cold forest landscapes, wildfires have enhanced biodiversity through the creation of structurally complex early-seral habitats. Area burned is expected to double or triple in the future under a warming climate. Strategies to adapt to future wildfires vary among historical regimes and biophysical settings and will require collaborative engagement and adaptive management to facilitate ecological change at meaningful scales.


Figure 1. Location of the study area in western USA (inset A), potential vegetation types reclassified into forest and grass/shrub (inset B) and MTBS 22 fire perimeters used in this analysis reclassified according to area burned in forested and burnable non-forested vegetation types. Figure produced with ArcMap 10.6.1 https:// deskt op. arcgis. com. Service layers credit: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, I.G.N., Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri, China (Hong Kong), © OpenStreetMap contributors and the GIS User Community.
Figure 2. Examples of classification of three fire events into fire types based on dominant vegetation type burned. (A) Pole Creek Fire, OR, 2012 was classified as a forest fire, (B) Cinder Butte fire, OR, 2017 was classified as a grass/shrub fire and (C) Carlton Complex fire, WA, 2014 was classified as a mixed fire. Figure produced with ArcMap 10.6.1 https:// deskt op. arcgis. com. Service layers credit: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, I.G.N., Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri, China (Hong Kong), © OpenStreetMap contributors and the GIS User Community.
Figure 3. Major land ownership classes in the Pacific Northwest, USA. BLM = Bureau of Land Management, FS = United States Forest Service. State/Oregon and State/Washington denote state managed lands. Other nonfederal lands not shown. Figure produced with ArcMap 10.6.1 https:// deskt op. arcgis. com. Service layers credit: Esri, HERE, Garmin, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, I.G.N., Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri, China (Hong Kong), © OpenStreetMap contributors and the GIS User Community.
Figure 4. Example of the delineation of used area and available area for a fire perimeter and three alternative patterns of fire use specific to a single target owner (shown in dark blue). The used area corresponds to the area burned by the fire (hashed) as mapped by MTBS 22 . The available area corresponds to the burned area (i.e., used) plus an outside buffer. The buffer width is defined so that the buffer has the same area as the fire. We include the burned area into our definition of available because in order to be burned it needed to be available to burn. The target owner is avoided by fire (left panel) if area burned does not intersect with the target owner, but is available within the buffer. A Jacobs value of -1 represents perfect avoidance when 100% of the target owner is available but unburned. On the opposite end of the Jacobs' range is preference with Jacobs' = 1 (right panel). A fire shows perfect preference for the target owner when area burned is completely contained within the used area. Indifference (Jacobs' = 0; middle panel) happens when the proportion of the fire in the used and the available areas are the same. Figure produced with ArcGIS Pro 2.4.1 (www. esri. com).
Figure 5. Violin plots showing the distribution of Jacobs' selectivity index values by ownership for forest fires (red circles). Jacobs' = 1 indicates perfect preference, Jacobs' = −1 indicates perfect avoidance and Jacobs' = 0 represents indifference. Ownerships associated with fewer than 25 observations are not shown (Other and Tribal). White dot represents the median value, thick black lines represent the interquartile range and the thin vertical lines show the 95% confidence interval for the median. Grey shaded area shows a rotated kernel density plot on each side. A horizontal jitter factor was applied to distribute data points horizontally so that similar values did not overlap on the same point. Figure produced with MatLAB 2019a (www. mathw orks. com).

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Effects of ownership patterns on cross-boundary wildfires

September 2021

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873 Reads

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7 Citations

Understanding ownership effects on large wildfires is a precursor to the development of risk governance strategies that better protect people and property and restore fire-adapted ecosystems. We analyzed wildfire events in the Pacific Northwest from 1984 to 2018 to explore how area burned responded to ownership, asking whether particular ownerships burned disproportionately more or less, and whether these patterns varied by forest and grass/shrub vegetation types. While many individual fires showed indifference to property lines, taken as a whole, we found patterns of disproportionate burning for both forest and grass/shrub fires. We found that forest fires avoided ownerships with a concentration of highly valued resources—burning less than expected in managed US Forest Service forested lands, private non-industrial, private industrial, and state lands—suggesting the enforcement of strong fire protection policies. US Forest Service wilderness was the only ownership classification that burned more than expected which may result from the management of natural ignitions for resource objectives, its remoteness or both. Results from this study are relevant to inform perspectives on land management among public and private entities, which may share boundaries but not fire management goals, and support effective cross-boundary collaboration and shared stewardship across all-lands.


Species abundance has changed in mixed‐conifer forests in recent decades. Estimates of (a) basal area per hectare (BAH) and (b) trees per hectare (TPH) on public lands in eastern Oregon and Washington were compiled from national and regional forest inventories. For each diameter class, bars from left to right represent estimates for midpoint inventory years 1995 (1990–1999), 2004 (2000–2007), and 2014 (2010–2017). Species include the fire‐tolerant and shade‐intolerant ponderosa pine (Pinus ponderosa, PIPO) and western larch (Larix occidentalis, LAOC); the shade‐tolerant white fir (Abies concolor) or grand fir (Abies grandis) (together, ABCOGR) and Douglas fir (Pseudotsuga menziesii, PSME); and all other tree species combined (Other). Species proportions in 2004 and 2014 are relative to the BAH (above) and TPH totals (below) in 1995, for each diameter class. Diameter class midpoints are (left to right) 10 cm (range 2.5–20 cm), 30 cm (range 20–40 cm), 50 cm (range 40–60 cm), and 90 cm (range 60–120 cm). Results show overall increases in BAH and TPH for tree diameters >40 cm, with ABCOGR and PSME increasing more than PIPO, and LAOC generally declining. Error bars represent the standard error of the mean estimate. (a) The proportions of total BAH in the 10‐cm, 30‐cm, 50‐cm, and 90‐cm midpoint classes in 2014 were 16.9%, 35.1%, 27.5%, and 20.6%, respectively. (b) The proportions of total TPH in the 10‐cm, 30‐cm, 50‐cm, and 90‐cm midpoint classes in 2014 were 79.9%, 14.5%, 4.2%, and 1.4%, respectively. Note that the largest increases in BAH and TPH occurred in the 50‐cm class.
A densely treed landscape emerges. Panoramic photographs – taken from Duncan Hill, Washington, looking southeast along the Entiat River drainage to the Columbia River – show the majority of the 238,000‐ha Entiat drainage in (a) 1934 and (b) 2012. Fire exclusion and selection cutting broadly homogenized successionally diverse pine forests, and dry and moist mixed‐conifer forests. In the absence of wildfires, bark beetles kill trees, increase fuels, and synchronize large areas for burning.
(a) RR Sarlin; National Archives and Records Administration, Seattle
View near Tronsen Ridge (in the background), 2013, Okanogan‐Wenatchee National Forest, Washington. Only a handful of trees in this scene were present 125 to 150 years ago. The largest ponderosa pines are 300 to 400 years old, developing under a frequent fire regime. Most other trees are fire‐intolerant grand fir and Douglas fir that established over the period of livestock grazing and fire exclusion. A few dwarf mistletoe infested younger western larch are dead in this scene owing to extreme intertree competition for soil moisture and nutrients, and mistletoe infection severity.
Young shade‐tolerant and fire‐intolerant trees rapidly fill in the forest. Over 150 years, a dry and moist mixed‐conifer forest landscape has become densely filled with Douglas fir and grand fir pole‐, small‐, medium‐, and large‐sized trees. View looking southwest into Stafford Creek, North Fork Teanaway River watershed, Cle Elum, Washington, in (a) 1934 and (b) 2013.
(a) RL Cooper; National Archives and Records Administration, Seattle
Climate and wildfire adaptation of inland Northwest US forests

September 2021

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223 Reads

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15 Citations

After a century of intensive logging, federal forest management policies were developed in the 1990s to protect remaining large trees and old forests in the western US. Today, due to rapidly changing ecological conditions, new threats and uncertainties, and scientific advancements, some policy provisions are being re‐evaluated in interior Oregon and Washington. The case for re‐evaluation is clearest where small‐ to large‐sized, immature, fast‐growing, fire‐intolerant trees have filled in forests after both a long period of fire exclusion and the harvest of large, old trees. This infilling has created abundant fuel ladders that increase patch and landscape vulnerability to severe wildfires, which now threaten many forests. As climate change continues to alter fire regimes, we recommend that landscape‐level planning is needed to determine where fire‐tolerant and intolerant forest successional conditions are best retained on the landscape. Critical to our proposal are effective public engagement, collaboration, and tribal consultation.


Twenty‐five years of the Northwest Forest Plan: what have we learned?

August 2019

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1,185 Reads

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68 Citations

The Northwest Forest Plan (NWFP) has guided the management of 17 federal forests in the US Pacific Northwest for the past 25 years. The existing management plans for these national forests – which were amended by the NWFP – are now being evaluated for revision under the US Forest Service's 2012 planning rule. To help inform federal land managers, we reviewed the scientific literature published since the inception of the NWFP and report several key findings: (1) conservation of at‐risk species within national forests is challenging in the face of threats that are beyond the control of federal managers, (2) management efforts to promote resilience to wildfire and climate change include restoring dynamics and structure at multiple scales and revisiting reserve design, (3) forest restoration can have an ecological and socioeconomic win–win outcome, (4) human communities benefit from many ecosystem services beyond the supply of timber, (5) collaboration among multiple stakeholders is essential for achieving ecological and socioeconomic goals, and (6) monitoring and adaptive management are crucial to learning about and addressing uncertainty.


Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests

July 2019

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1,730 Reads

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246 Citations

Before the advent of intensive forest management and fire suppression, western North American forests exhibited a naturally occurring resistance and resilience to wildfires and other disturbances. Resilience, which encompasses resistance, reflects the amount of disruption an ecosystem can withstand before its structure or organization qualitatively shift to a different basin of attraction. In fire-maintained forests, resilience to disturbance events arose primarily from vegetation pattern-disturbance process interactions at several levels of organization. Using evidence from 15 ecoregions, spanning forests from Canada to Mexico, we review the properties of forests that reinforced qualities of resilience and resistance. We show examples of multi-level landscape resilience, of feedbacks within and among levels, and how conditions have changed under climatic and management influences. We highlight geographic similarities and important differences in the structure and organization of historical landscapes, their forest types, and in the conditions that have changed resilience and resistance to abrupt or large-scale disruptions. We discuss the role of the regional climate in episodically or abruptly reorganizing plant and animal biogeography and forest resilience and resistance to disturbances. We give clear examples of these changes and suggest that managing for resilient forests is a construct that strongly depends on scale and human social values. It involves human communities actively working with the ecosystems they depend on, and the processes that shape them, to adapt landscapes, species, and human communities to climate change while maintaining core ecosystem processes and services. Finally, it compels us to embrace management approaches that incorporate ongoing disturbances and anticipated effects of climatic changes, and to support dynamically shifting patchworks of forest and non-forest. Doing so could make these shifting forest conditions and wildfire regimes less disruptive to individuals and society.


Is fire “for the birds”? How two rare species influence fire management across the US

July 2019

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583 Reads

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51 Citations

The US Endangered Species Act has enabled species conservation but has differentially impacted fire management and rare bird conservation in the southern and western US. In the South, prescribed fire and restoration‐based forest thinning are commonly used to conserve the endangered red‐cockaded woodpecker (Picoides borealis; RCW), whereas in the West, land managers continue to suppress fire across the diverse habitats of the northern, Californian, and Mexican spotted owls (Strix occidentalis subspecies; SO). Although the habitat needs of the RCW and SO are not identical, substantial portions of both species’ ranges have historically been exposed to relatively frequent, low‐ to moderate‐intensity fires. Active management with fire and thinning has benefited the RCW but proves challenging in the western US. We suggest the western US could benefit from the adoption of a similar innovative approach through policy, public–private partnerships, and complementarity of endangered species management with multiple objectives. These changes would likely balance long‐term goals of SO conservation and enhance forest resilience.


Use of Science and Modeling by Practitioners in Landscape-Scale Management Decisions

April 2019

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30 Reads

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10 Citations

Journal of Forestry

Scientific knowledge and tools have central roles in contemporary federal forest programs that promote restoration in large landscapes and across ownerships. Although we know much about the role of science in decisionmaking and ways that science can be better linked to practice, we know less about manager perspectives about science and science tools, and the perceived role of both in planning. We surveyed Forest Service resource managers in the western United States to address this knowledge gap. Respondents engaged most frequently with science via reading research publications; direct engagement with scientists was less common. There was widespread agreement that science was a useful input to decisionmaking. Managers believed more weight should be placed on science in decisionmaking in cases of low public consensus than in cases of high public consensus. Managers with the most frequent engagement with science generally held more positive views towards science and its role in decisionmaking.


Citations (78)


... For example, in western United States forests, the annual area burned at high severity has increased by eightfold since 1985 (Parks and Abatzoglou, 2020) and increasing high-severity patch size has been homogenizing forests (Singleton et al., 2021;Cova et al., 2023). The cause of changing fire regimes is context-specific and therefore depends on the system in question (Jones et al., 2022a). But the primary drivers typically include a combination of warming and drying climate conditions (Abatzoglou and Williams, 2016;Juang et al., 2022) as well as past and ongoing fire exclusion resulting in homogenous conditions with unnaturally large accumulations of fuel (Koontz et al., 2020;Francis et al., 2023;Kreider et al., 2024). ...

Reference:

Prescribed fire, managed burning, and previous wildfires reduce the severity of a southwestern US gigafire
Counteracting wildfire misinformation

... California), delineated using EPA Level III Ecoregions (Commission for Environmental Cooperation, 1997) ( Figure 1). Climate, topography, and forest types vary widely across the northwestern United States (Hood et al., 2021;Reilly et al., 2021). Historical fire regimes range from frequent and predominantly low-severity fire in warmer and drier parts of the region to infrequent and predominantly high-severity fire in cooler and wetter parts of the region (Agee, 1993;Baker, 2009;Hood et al., 2021;Reilly et al., 2021). ...

Fire Ecology and Management in Pacific Northwest Forests

... Transboundary pollution such as smoke and pollutants from wildfires can cross national borders, affecting neighboring countries and even continents. This can lead to international tensions and the need for cross-border cooperation on air quality management [14,29]. Additionally, large-scale wildfires can influence global climate patterns, potentially affecting weather systems and contributing to phenomena such as El Niño and La Niña [30][31][32][33][34][35][36][37][38]. ...

Effects of ownership patterns on cross-boundary wildfires

... Land management in the modern era faces unprecedented uncertainty regarding future climatic changes, novel disturbance regimes, and unanticipated ecological feedbacks (Millar et al. 2007;Millar and Stephenson 2015;Hessburg et al. 2015Hessburg et al. , 2021Schuurman et al. 2022). Wildfire poses both a challenge and a solution to these projected changes (Dombeck et al. 2004;North et al. 2015), and building climate-adapted forest landscapes will require restoring active wildfire regimes and reducing the fire deficit across much of the intermountain west (Moritz et al. 2014;Schoennagel et al. 2017;Hessburg et al. 2019). ...

Climate and wildfire adaptation of inland Northwest US forests

... AM was first utilised in the USFS in 1994 in the 10-million-hectare Northwest Forest Plan in response to over harvesting of the old-growth forests which serve as habitat for endangered wildlife such as the Northern Spotted Owl (Strix occidentalis caurina) [33], [34]. Lessons learned from over 25 years of applying AM in this plan are collaboration amongst stakeholders is key for achieving social-ecological goals and objectives, M&E in AM is vital for learning at multiple scales and for minimising uncertainty, AM can be costly, and that the plan is not adequately addressing climate change, wildfires, trade-offs and social values [33], [35]. The plan has been deemed a success in conserving old-growth forests and wildlife as originally intended [35]. ...

Twenty‐five years of the Northwest Forest Plan: what have we learned?

... Forests in the southwestern USA have experienced natural disturbances such as wildfire and insect-caused mortality for millennia (Hessburg et al., 2019). Our results suggested that the nocturnal space use of Mexican spotted owls (e.g., indicative of foraging habitat) appears to align with characteristics that are consistent with the region's historical disturbance regimes. ...

Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests

... Prescribed fires are planned, controlled fires that have multiple benefits for the ecosystem health, 1 hazard reduction, 2 and endangered wildlife protection. 3 Also, prescribed burning is a land management tool that can reduce the likelihood of catastrophic wildfires. 4,5 However, both prescribed fires and wildfires emit significant amounts of pollutants such as particulate matter with aerodynamic diameter less than 2.5 μm (PM 2.5 ), volatile organic compounds (VOCs), and nitrogen oxides (NO x ) into the troposphere, and these pollutants have adverse health impacts. ...

Is fire “for the birds”? How two rare species influence fire management across the US

... Land-use changes and short-rotation forestry over the last century have resulted in a deficit of these late-successional forests, and wildfire and insect disturbances associated with climate change may reduce intact primary forests even more [4]. There is an increasing need to understand the long-term impacts of old-growth preservation and restoration on timber production and biodiversity [5,6] as well as for carbon storage [7][8][9], especially regarding soil C [1]. ...

Synthesis of science to inform land management within the Northwest Forest Plan area
  • Citing Technical Report
  • June 2018

... In contrast, frequent low-or intermediate-severity fire tends to primarily kill understory trees and promote the survival of large, fire-resistant pioneer tree species. Old-growth structure in frequent-fire regime forests consisted of shifting mosaics of structural patches in all developmental stages that collectively constitute a stand that may be considered mature or old-growth ( Fig. 4; Franklin et al., 2002;Spies et al., 2018b), or in a variety of patch sizes across a landscape (Kaufmann et al., 2007;North et al., 2009;Larson and Churchill, 2012). Abundance of shadetolerant trees and layered canopies was low except in less fire-prone topographic positions, and levels of large snags and dead downed wood were much lower than in less frequent fire regimes (Lorimer and White, 2003;Fraver and Palik, 2012;Hessburg et al., 2015). ...

Synthesis of science to inform land management within the Northwest Forest Plan area: executive summary
  • Citing Technical Report
  • January 2018

... In addition to these basic requirements, habitat suitability models intended to inform planning and permitting decisions on public lands must have a spatial resolution and accuracy that allows for their use at local scales (e.g., to inform decisions about the best placement of individual oil and gas wells to minimize loss of both occupied and suitable habitat for the species). Public land managers may be hesitant or unwilling to use models if they do not understand how they were developed, and as a result do not trust their quality (Addison et al., 2013;Sofaer et al., 2019;White et al., 2019). ...

Use of Science and Modeling by Practitioners in Landscape-Scale Management Decisions
  • Citing Article
  • April 2019

Journal of Forestry