Modern calibration and historical testing of small-area, fire-interval reconstruction methods

Dugan, Alexa J.; Baker, William L.

doi:10.1071/wf12162

Cited by 7 publications

(14 citation statements)

References 19 publications

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“…Finally, we developed an estimator, the mean all-tree fire interval (mean ATFI), which seeks to offset SF < 1.0 by using an estimated SF to predict the total number of scars that would have occurred if SF was 1.0 [ 7 – 8 , 11 ]. This estimator has been shown to be the best available estimator of PMFI [ 11 ], but it is not used in this paper because few ATFI estimates are currently available.…”

Section: Measures and Estimators Of Mean Rates Of Low-severity Firesmentioning

confidence: 99%

“…Larger fires that contribute most to fire rotation are mapped the best. Fire rotation has been shown to be estimated within about 10% of the value obtained from fire-atlas data [ 1 , 11 ].…”

Section: Measures and Estimators Of Mean Rates Of Low-severity Firesmentioning

confidence: 99%

“…Past reconstructions of low-severity fire in dry forests, using tree-rings, focused on long records of dated fire years in small plots, and most were not intended to accurately estimate key rate parameters of low-severity fire [ 1 – 2 ] needed to restore and manage low-severity fire across large landscapes. These small-plot reconstructions have known inaccuracies and biases if inappropriately used for this purpose [ 1 , 4 – 11 ]. Fortunately, new landscape-scale and small-plot reconstruction methods [ 1 , 11 ] overcome many known inaccuracies and biases in estimating historical low-severity fire rates, but limited new estimates are available.…”

Section: Introductionmentioning

confidence: 99%

“…These small-plot reconstructions have known inaccuracies and biases if inappropriately used for this purpose [ 1 , 4 – 11 ]. Fortunately, new landscape-scale and small-plot reconstruction methods [ 1 , 11 ] overcome many known inaccuracies and biases in estimating historical low-severity fire rates, but limited new estimates are available.…”

Section: Introductionmentioning

confidence: 99%

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Restoring and managing low-severity fire in dry-forest landscapes of the western USA

Baker

2017

PLoS ONE

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Low-severity fires that killed few canopy trees played a significant historical role in dry forests of the western USA and warrant restoration and management, but historical rates of burning remain uncertain. Past reconstructions focused on on dating fire years, not measuring historical rates of burning. Past statistics, including mean composite fire interval (mean CFI) and individual-tree fire interval (mean ITFI) have biases and inaccuracies if used as estimators of rates. In this study, I used regression, with a calibration dataset of 96 cases, to test whether these statistics could accurately predict two equivalent historical rates, population mean fire interval (PMFI) and fire rotation (FR). The best model, using Weibull mean ITFI, had low prediction error and R2adj = 0.972. I used this model to predict historical PMFI/FR at 252 sites spanning dry forests. Historical PMFI/FR for a pool of 342 calibration and predicted sites had a mean of 39 years and median of 30 years. Short (< 25 years) mean PMFI/FRs were in Arizona and New Mexico and scattered in other states. Long (> 55 years) mean PMFI/FRs were mainly from northern New Mexico to South Dakota. Mountain sites often had a large range in PMFI/FR. Nearly all 342 estimates are for old forests with a history of primarily low-severity fire, found across only about 34% of historical dry-forest area. Frequent fire (PMFI/FR < 25 years) was found across only about 14% of historical dry-forest area, with 86% having multidecadal rates of low-severity fire. Historical fuels (e.g., understory shrubs and small trees) could fully recover between multidecadal fires, allowing some denser forests and some ecosystem processes and wildlife habitat to be less limited by fire. Lower historical rates mean less restoration treatment is needed before beginning managed fire for resource benefits, where feasible. Mimicking patterns of variability in historical low-severity fire regimes would likely benefit biological diversity and ecosystem functioning.

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Section: Measures and Estimators Of Mean Rates Of Low-severity Firesmentioning

confidence: 99%

Section: Measures and Estimators Of Mean Rates Of Low-severity Firesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Restoring and managing low-severity fire in dry-forest landscapes of the western USA

Baker

2017

PLoS ONE

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“…Mallek et al's conclusion that lowerseverity fires are burning at lower rates than historically may be valid, but valid evidence is very limited. New landscape (Farris et al 2010) and plot-based methods (Dugan and Baker 2014) can produce valid and accurate estimates, but many more are needed.…”

Section: Management Implicationsmentioning

confidence: 99%

Historical forest structure and fire in Sierran mixed‐conifer forests reconstructed from General Land Office survey data

Baker

2014

Ecosphere

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150

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Abstract. Dry forests of the western United States (ponderosa pine, dry mixed conifer) are often considered at risk of uncharacteristic severe fires, but recent research has found historically extensive severe fire. This has left divergent perspectives about how to restore dry forests, protect people and infrastructure from fire, and interpret the ecological effects of large fires, such as the 2013 Rim fire, a human-set 104,000 ha fire in the western Sierra Nevada Mountains. To help resolve this uncertainty, I used new methods to reconstruct historical forest structure and fire and test 11 hypotheses about them, using A.D. 1865-1885 General Land Office surveys, across 330,000 ha of Sierran mixed-conifer forests. The reconstructions show these historical forests were open and park-like in places, but generally dense, averaging 293 trees/ha; shade-tolerant trees and large trees were abundant, but smaller (,60 cm diameter) pines and oaks numerically dominated. These smaller trees, along with common understory seedlings and saplings and almost pervasive shrubs, created abundant ladder fuels. It is not surprising, given these conditions, that just 13-26% of historical Sierran mixed-conifer forests had only low-severity fire, with mixed-severity fire over 43-48%, and high-severity fire over 31-39% of the land area. The high-severity fire rotation was 281 years in the northern and 354 years in the southern Sierra, short enough to contribute to high levels of heterogeneity, including abundant areas and large patches (up to 9400 ha) of earlysuccessional forest and montane chaparral, but long enough to allow recovery of old-growth forest over large land areas. Proposals to reduce fuels and fire severity would actually reduce, not restore, historical forest heterogeneity important to wildlife and resiliency. Sierran mixed-conifer forests are inherently dangerous places to live, which cannot be changed without creating artificial forests over large land areas. However, people can adapt to fires by channeling development to safer areas and modifying ignition zones near houses and communities to survive fire.

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Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

Hagmann

Hessburg

Prichard

et al. 2021

Ecological Applications

223

140

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Implementation of wildfire-and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change and lack of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low-and moderate-KEYWORDS

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Modern calibration and historical testing of small-area, fire-interval reconstruction methods

Cited by 7 publications

References 19 publications

Restoring and managing low-severity fire in dry-forest landscapes of the western USA

Restoring and managing low-severity fire in dry-forest landscapes of the western USA

Historical forest structure and fire in Sierran mixed‐conifer forests reconstructed from General Land Office survey data

Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests

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