Overestimation of Fire Risk in the Northern Spotted Owl Recovery Plan

Hanson, Chad T.; Odion, Dennis C.; DellaSala, Dominick A.; Baker, William L.

doi:10.1111/j.1523-1739.2009.01265.x

Cited by 55 publications

(51 citation statements)

References 15 publications

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“…4). The fraction of total fire burning at high severity in dry forests of the eastern Cascades also did not increase from 1984-2005(Hanson et al 2009. If the goal is maintaining or restoring historical fire regimes, treating large land areas (e.g., about 45% of dry forests in 20 years; Johnson and Franklin 2009) to reduce highseverity fire would, if effective, substantially add to fire exclusion and alter or degrade, not restore these forests.…”

Section: Fuel Reduction Is Not Ecological Restoration In Dry Forestsmentioning

confidence: 95%

“…4). Also, the risk of high-severity fire has not increased relative to historical landscapes, as the 435-year approximation of historical high-severity fire rotation is little different from the 469-year recent high-severity rotation in old forests in the eastern Oregon Cascades (Hanson et al 2009). The fraction of total fire burning at high severity also has not increased.…”

Section: Fuel Reduction Is Not Ecological Restoration In Dry Forestsmentioning

confidence: 99%

“…Uncharacteristic high-severity fires were thought to be threatening these forests and the owl (e.g., Spies et al 2006). However, recent research suggested dry forests and fire in the Northwest were variable historically (Hessburg et al 2007), and the fraction of fire that burned at high severity lacks a recent upward trend (Hanson et al 2009). However, detailed reconstructions of the variable historical structure and fire are not yet available to provide a reference framework for interpreting recent fire or for guiding restoration and management.…”

Section: Introductionmentioning

confidence: 99%

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Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades

Baker

2012

Ecosphere

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Abstract. Dry western forests (e.g., ponderosa pine and mixed conifer) were thought to have been historically old and park-like, maintained by low-severity fires, and to have become denser and more prone to high-severity fire. In the Pacific Northwest, early aerial photos (primarily in Washington), showed that dry forests instead had variable-severity fires and forest structure, but more detail is needed. Here I used pre-1900 General Land Office Surveys, with new methods that allow accurate reconstruction of detailed forest structure, to test eight hypotheses about historical structure and fire across about 400,000 ha of dry forests in Oregon's eastern Cascades. The reconstructions show that only about 13.5% of these forests had low tree density. Forests instead were generally dense (mean ¼ 249 trees/ha), but density varied by a factor of 2-4 across about 25,000-ha areas. Shade-tolerant firs historically were 17% of trees, dominated about 12% of forest area, and were common in forest understories. Understory trees and shrubs dominated on 83.5%, and were dense across 44.8% of forest area. Small trees (10-40 cm dbh) were .50% of trees across 72.3% of forest area. Low-severity fire dominated on only 23.5%, mixed-severity fire on 50.2%, and high-severity fire on 26.2% of forest area. Historical fire included modest-rotation (29-78 years) lowseverity and long-rotation (435 years) high-severity fire. Given historical variability in fire and forest structure, an ecological approach to restoration would restore fuels and manage for variable-severity fires, rather than reduce fuels to lower fire risk. Modest reduction in white fir/grand fir and an increase in large snags, down wood, and large trees would enhance recovery from past extensive logging and increase resiliency to future global change. These forests can be maintained by wildland fire use, coupled, near infrastructure, with prescribed fires that mimic historical low-severity fires.

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Section: Fuel Reduction Is Not Ecological Restoration In Dry Forestsmentioning

confidence: 95%

Section: Fuel Reduction Is Not Ecological Restoration In Dry Forestsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades

Baker

2012

Ecosphere

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“…The belief that recent fires, such as the 196,000-ha Biscuit Fire in 2002, were more severe than the historical norm could be used to justify managing fire hazard through thinning or prescribed fire in currently dense stands (12,13). However, some have questioned whether increased fuels from fire suppression indeed pose an increased risk of severe fire (14,15) and whether climate may override fuel as a control of fire occurrence and extent (10,16).…”

mentioning

confidence: 99%

Highly episodic fire and erosion regime over the past 2,000 y in the Siskiyou Mountains, Oregon

Colombaroli

Gavin

2010

Proc. Natl. Acad. Sci. U.S.A.

120

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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.historical fire | climate variability | ecological resilience | logging | sediment charcoal

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“…As in Hanson et al (2009), we analyzed only late-successional, or "older" forests present in 1995, as mapped by Moeur et al (2005). This is a small fraction of the dry forest regions.…”

Section: Study Areamentioning

confidence: 99%

Effects of Fire and Commercial Thinning on Future Habitat of the Northern Spotted Owl

Odion¹,

Hanson²,

DellaSala³

et al. 2014

TOORTHJ

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Abstract:The Northern Spotted Owl (Strix occidentalis caurina) is an emblematic, threatened raptor associated with dense, late-successional forests in the Pacific Northwest, USA. Concerns over high-severity fire and reduced timber harvesting have led to programs to commercially thin forests, and this may occur within habitat designated as "critical" for spotted owls. However, thinning is only allowed under the U.S. Government spotted owl guidelines if the long-term benefits clearly outweigh adverse impacts. This possibility remains uncertain. Adverse impacts from commercial thinning may be caused by removal of key habitat elements and creation of forests that are more open than those likely to be occupied by spotted owls. Benefits of thinning may accrue through reduction in high-severity fire, yet whether the firereduction benefits accrue faster than the adverse impacts of reduced late-successional habitat from thinning remains an untested hypothesis. We found that rotations of severe fire (the time required for high-severity fire to burn an area equal to the area of interest once) in spotted owl habitat since 1996, the earliest date we could use, were 362 and 913 years for the two regions of interest: the Klamath and dry Cascades. Using empirical data, we calculated the future amount of spotted owl habitat that may be maintained with these rates of high-severity fire and ongoing forest regrowth rates with and without commercial thinning. Over 40 years, habitat loss would be far greater than with no thinning because, under a "best case" scenario, thinning reduced 3.4 and 6.0 times more dense, late-successional forest than it prevented from burning in high-severity fire in the Klamath and dry Cascades, respectively. Even if rates of fire increase substantially, the requirement that the long-term benefits of commercial thinning clearly outweigh adverse impacts is not attainable with commercial thinning in spotted owl habitat. It is also becoming increasingly recognized that exclusion of high-severity fire may not benefit spotted owls in areas where owls evolved with reoccurring fires in the landscape.

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Overestimation of Fire Risk in the Northern Spotted Owl Recovery Plan

Cited by 55 publications

References 15 publications

Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades

Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades

Highly episodic fire and erosion regime over the past 2,000 y in the Siskiyou Mountains, Oregon

Effects of Fire and Commercial Thinning on Future Habitat of the Northern Spotted Owl

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