Differential impacts of wildfire on the population dynamics of an old‐forest species

Rockweit, Jeremy T.; Franklin, Alan B.; Carlson, Peter C.

doi:10.1002/ecy.1805

Cited by 52 publications

(63 citation statements)

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“…Post-fire logging is likely to be partially responsible for some of the negative effects attributed to high-severity fire in the studies reviewed here (Tempel et al 2014, Jones et al 2016, Rockweit et al 2017, Hanson et al 2018. Because Spotted Owl studies typically characterize territory vegetation only in the breeding core area within 1.1 km of the nest, these studies ignore habitat changes and alterations in the year-round home-range area that can extend up to 5.9 km from the nest (Zabel et al 1992).…”

Section: Discussionmentioning

confidence: 99%

Spotted Owls and forest fire: a systematic review and meta‐analysis of the evidence

Lee

2018

Ecosphere

143

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Forest and Spotted Owl management documents often state that severe wildfire is a cause of recent declines in populations of Spotted Owls and that mixed‐severity fires (5–70% of burned area in high‐severity patches with >75% mortality of dominant vegetation) pose a primary threat to Spotted Owl population viability. This systematic review and meta‐analysis summarize all available scientific literature on the effects of wildfire on Spotted Owl demography and ecology from studies using empirical data to answer the question: How does fire, especially recent mixed‐severity fires with representative patches of high‐severity burn within their home ranges, affect Spotted Owl foraging habitat selection, demography, and site occupancy parameters? Fifteen papers reported 50 effects from fire that could be differentiated from post‐fire logging. Meta‐analysis of mean standardized effects (Hedge's d) found only one parameter was significantly different from zero, a significant positive foraging habitat selection for low‐severity burned forest. Multi‐level mixed‐effects meta‐regressions (hierarchical models) of Hedge's d against percent of study area burned at high severity and time since fire found the following: a negative correlation of occupancy with time since fire; a positive effect on recruitment immediately after the fire, with the effect diminishing with time since fire; reproduction was positively correlated with the percent of high‐severity fire in owl territories; and positive selection for foraging in low‐ and moderate‐severity burned forest, with high‐severity burned forest used in proportion to its availability, but not avoided. Meta‐analysis of variation found significantly greater variation in parameters from burned sites relative to unburned, with specifically higher variation in estimates of occupancy, demography, and survival, and lower variation in estimates of selection probability for foraging habitat in low‐severity burned forest. Spotted Owls were usually not significantly affected by mixed‐severity fire, as 83% of all studies and 60% of all effects found no significant impact of fire on mean owl parameters. Contrary to current perceptions and recovery efforts for the Spotted Owl, mixed‐severity fire does not appear to be a serious threat to owl populations; rather, wildfire has arguably more benefits than costs for Spotted Owls.

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Section: Discussionmentioning

confidence: 99%

Spotted Owls and forest fire: a systematic review and meta‐analysis of the evidence

Lee

2018

Ecosphere

143

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“…Nonetheless, regeneration of older forest is a relatively slow process occurring over many decades and is threatened by a variety of factors including large, high‐severity forest wildfires in some parts of the NSO geographic range (Rockweit et al. ). Therefore, BO removals remain an important management action to promote NSO persistence over shorter time scales.…”

Section: Discussionmentioning

confidence: 99%

“…, Rockweit et al. ). Even without further loss, recruitment of old forest was expected to take many decades (Lint et al.…”

Section: Introductionmentioning

confidence: 99%

The past and future roles of competition and habitat in the range‐wide occupancy dynamics of Northern Spotted Owls

Yackulic

Bailey

Dugger

et al. 2019

Ecological Applications

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Slow ecological processes challenge conservation. Short‐term variability can obscure the importance of slower processes that may ultimately determine the state of a system. Furthermore, management actions with slow responses can be hard to justify. One response to slow processes is to explicitly concentrate analysis on state dynamics. Here, we focus on identifying drivers of Northern Spotted Owl (Strix occidentalis caurina) territorial occupancy dynamics across 11 study areas spanning their geographic range and forecasting response to potential management actions. Competition with Barred Owls (Strix varia) has increased Spotted Owl territory extinction probabilities across all study areas and driven recent declines in Spotted Owl populations. Without management intervention, the Northern Spotted Owl subspecies will be extirpated from parts of its current range within decades. In the short term, Barred Owl removal can be effective. Over longer time spans, however, maintaining or improving habitat conditions can help promote the persistence of northern spotted owl populations. In most study areas, habitat effects on expected Northern Spotted Owl territorial occupancy are actually greater than the effects of competition from Barred Owls. This study suggests how intensive management actions (removal of a competitor) with rapid results can complement a slower management action (i.e., promoting forest succession).

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“…, , Rockweit et al. ). The effects of fire on individual northern spotted owls and habitat quality are complex and not fully understood (Lesmeister et al.…”

Section: Introductionmentioning

confidence: 99%

“…Persistence of native wildlife species that are adapted to historical fire regimes may be at risk given climate change and land management practices that alter patterns in fire frequency and intensity relative to historical patterns. For example, in many dry forests the extent of areas impacted by high-severity fire is increasing, with concern for sensitive wildlife species that rely on forest types altered by fire (Westerling et al 2006, Miller et al 2008, Reilly et al 2017, Rockweit et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Mixed‐severity wildfire and habitat of an old‐forest obligate

et al. 2019

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The frequency, extent, and severity of wildfire strongly influence the structure and function of ecosystems. Mixed‐severity fire regimes are the most complex and least understood fire regimes, and variability of fire severity can occur at fine spatial and temporal scales, depending on previous disturbance history, topography, fuel continuity, vegetation type, and weather. During high fire weather in 2013, a complex of mixed‐severity wildfires burned across multiple ownerships within the Klamath‐Siskiyou ecoregion of southwestern Oregon where northern spotted owl (Strix occidentalis caurina) demographics were studied since 1990. A year prior to these wildfires, high‐resolution, remotely sensed forest structural information derived from light detection and ranging (lidar) data was acquired for an area that fully covered the extent of these fires. To quantify wildfire impact on northern spotted owl nesting/roosting habitat, we fit a relative habitat suitability model based on pre‐fire locations used for nesting and roosting, and forest structure variables developed from 2012 lidar data. Our pre‐fire habitat suitability model predicted nesting/roosting locations well, and variable response functions followed known resource selection patterns. These forests had typical characteristics of old‐growth forest, with high density of large live trees, high canopy cover, and complex structure in canopy height. We projected the pre‐fire model onto lidar data collected two months post‐fire to produce a post‐fire suitability map, which indicated that >93% of pre‐fire habitat that burned at high severity was no longer suitable forest for nesting and roosting. We also quantified the probability that pre‐fire nesting/roosting habitat would burn at each severity class (unburned/low, low, moderate, high). Pre‐fire nesting/roosting habitat had lower probability of burning at moderate or high severity compared to other forest types under high burning conditions. Our results indicate that northern spotted owl habitat can buffer the negative effects of climate change by enhancing biodiversity and resistance to high‐severity fires, which are predicted to increase in frequency and extent with climate change. Within this region, protecting large blocks of old forests could be an integral component of management plans that successfully maintain variability of forests in this mixed‐ownership and mixed‐severity fire regime landscape and enhance conservation of many species.

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Differential impacts of wildfire on the population dynamics of an old‐forest species

Cited by 52 publications

References 50 publications

Spotted Owls and forest fire: a systematic review and meta‐analysis of the evidence

Spotted Owls and forest fire: a systematic review and meta‐analysis of the evidence

The past and future roles of competition and habitat in the range‐wide occupancy dynamics of Northern Spotted Owls

Mixed‐severity wildfire and habitat of an old‐forest obligate

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