Snag longevity of Douglas-fir, western hemlock, and western redcedar from permanent sample plots in coastal British Columbia

Parish, Roberta; Antos, Joseph A.; Ott, Peter K.; Lucca, C. Mario Di

doi:10.1016/j.foreco.2009.11.022

Cited by 24 publications

(22 citation statements)

References 32 publications

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“…8; table 4). Like Parish et al (2010) and Mellen and Ager (2002), we found a tendency for low snag fall rates on the part of P. menziesii ( fig. 8; table 4).…”

Section: Snag Fall and Fragmentationsupporting

confidence: 88%

“…Snag abundance and longevity after fire are influenced by several key factors, including the types of trees most likely to perish and become snags, and the length of time those snags remain standing, without breaking or falling down. Other studies have suggested strong effects of diameter and species; in particular, P. menziesii appears to be considerably more resistant to death by fire (Ryan and Reinhardt 1988), and, once converted to a snag, more resistant to falling (Parish et al 2010). The expectations of managers, and realism of models like CWDM, could be improved with detailed data about tree mortality, snag fall, and snag fragmentation from a postfire landscape.…”

Section: Introductionmentioning

confidence: 99%

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Natural tree regeneration and coarse woody debris dynamics after a forest fire in the western Cascade Range

Brown¹,

Kertis²,

Huff³

2013

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Cover photosPlot number 16 at 7 and 14 years after fire. At 7 years, there is abundant regeneration of Pseudotsuga menziesii under a canopy of snags. At 14 years, the snag canopy is thinning out owing to snag fall and fragmentation; tree, shrub, and herb regeneration mix but trees are the tallest elements.This work was performed under USDA Forest Service PO AG-04T0-P-10-0057. We monitored coarse woody debris dynamics and natural tree regeneration over a 14-year period after the 1991 Warner Creek Fire, a 3631-ha (8,972-ac) mixedseverity fire in the western Cascade Range of Oregon. Rates for tree mortality in the fire, postfire mortality, snag fall, and snag fragmentation all showed distinct patterns by tree diameter and species, with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) more likely to survive a fire, and to remain standing as a snag, than other common tree species. Natural seedling regeneration was abundant, rapid, and highly variable in space. Densities of seedlings >10 cm height at 14 years postfire ranged from 1,530 to 392,000 per ha. Seedling establishment was not concentrated in a single year, and did not appear to be limited by the abundant growth of shrubs.The simultaneous processes of mortality, snag fall, and tree regeneration increased the variety of many measures of forest structure. The singular event of the fire has increased the structural diversity of the landscape.Keywords: Fire severity, monitoring, coarse woody debris, reforestation, snag recruitment, regeneration. SummaryWe monitored natural tree regeneration and coarse woody debris dynamics over 14 years following the 1991 Warner Creek Fire, a 3,631-ha (8,972-ac) mixed-severity fire in the western Cascade Range of Oregon. The results provide a detailed picture of the variety of natural postfire conditions in westside Cascade forests, and demonstrate how a single mixed-severity fire can increase variety in forest structures.We studied 24 permanent plots representative of the burned area and its mix of fire severities, which ranged from 0.1 to 100 percent of prefire canopy killed. Plots This postfire mortality rate was higher in plots with higher initial fire severity.Much of the new snag volume quickly transferred to the ground via snag fall and fragmentation. Small snags, and A. amabilis snags, were more likely to fall. Larger snags were more likely to fragment.Natural seedling regeneration was abundant, and highly variable in space. Densities of seedlings >10 cm height at 14 years postfire ranged from 1,670 to 392,000 per ha in the higher elevation zone, and from 1,530 to 47,500 per ha in the lower zone. New seedlings were observed over all study visits, in patterns demonstrating that establishment was not concentrated in a single year. The growth of shrubs was abundant but did not appear to be limiting tree regeneration. The mixed-severity fire, followed by variable mortality, snag fall, and tree regeneration, led to an increase in variability, among plots, of several metrics of forest structure. The prominence of P. menziesii ...

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“…8; table 4). Like Parish et al (2010) and Mellen and Ager (2002), we found a tendency for low snag fall rates on the part of P. menziesii ( fig. 8; table 4).…”

Section: Snag Fall and Fragmentationsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Natural tree regeneration and coarse woody debris dynamics after a forest fire in the western Cascade Range

Brown¹,

Kertis²,

Huff³

2013

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“…The DBH effects on snag longevity were not obvious in some species (Table 5). Parish et al (2010) and Vanderwel et al (2006a) suggested that the positive DBH effects could relate to the higher ratio of heartwood to sapwood in larger snags because heartwood is more decay-resistant and provides the most structural support. Thus, snag longevity will be shorter in trees with extensive heartwood decay.…”

Section: Discussionmentioning

confidence: 99%

“…For conifers, increasing DBH had a positive effect on snag longevity (Garber et al 2005;Keen 1955;Lyon 1977;Parish et al 2010). For example, for Tsuga heterophylla (Raf.)…”

Section: Introductionmentioning

confidence: 99%

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Do larger snags stand longer?—snag longevity in mixed conifer–hardwood forests in Hokkaido, Japan

Onodera

Tokuda

2015

Annals of Forest Science

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Abstract& Key message More than half of the dead trees fell down within decade. Besides, DBH effect on snag longevity varied by tree species and was not detected for some species. Management of long-lived snags in temperate mixed forests should be reconsidered. & Context Snags (standing dead trees) provide essential habitats for many species. Those with large diameter at breast height (DBH) are prioritized for retention; one of the reasons is that snag longevity (recruitment to falling down) increases with increasing DBH in conifer-dominated forests. Despite its importance, the DBH effect on hardwood snags is inadequately understood. & Aims The aim of this study is to investigate whether and how the DBH effect varies by tree species in mixed coniferhardwood forests. & Methods We checked the current status (standing or falling) of dead trees that had been recorded in 37 permanent plots and applied a generalized linear mixed model. We used tree species, time since death, DBH, and interaction terms as variables. & Results Half of the dead trees with a DBH of 25 cm were estimated to have fallen down within 1-6 years for most of the species. While snag longevity increased with increasing DBH in Abies sachalinensis and Phellodendron amurense, we detected no such effect in Picea and three hardwood species. & Conclusions For highly decayed or long-lived snags, retaining large snags is not always effective. Managers of species-rich mixed forests should consider the variability of the DBH effects and management of dead wood before and after tree mortality.

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Snag decomposition following stand‐replacing wildfires alters wildlife habitat use and surface woody fuels through time

Peterson

Dodson

Harrod³

2023

Ecosphere

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High‐severity wildfires create pulses of snags that serve a variety of functions as they decompose over time. Snag‐related benefits (and hazards) are often linked to specific decomposition stages, but snag decomposition rates and pathways are not well understood in many forest types. We examined temporal patterns of snag decomposition, wildlife cavity creation, and surface woody fuel dynamics in dry coniferous forests of the interior Pacific Northwest region of North America by sampling 159 forest stands within a 39‐year chronosequence of stand‐replacing wildfires in dry coniferous forests dominated by ponderosa pine and Douglas‐fir. We found that most snags broke or fell during the first 15 years after wildfire; small‐diameter snags mostly broke off at or near ground level, while many large‐diameter snags initially broke off above a height of 2 m and then remained standing for an extended period. Ponderosa pine and lodgepole pine snags fell earlier than Douglas‐fir and true fir snags of comparable diameter classes. Wildlife cavities were most common in stands surveyed 8–20 years after fire and in snags with broken tops but were not limited to large diameter snags. Cavity snag diameters ranged from 17 to 98 cm, with 64% of cavity snags having diameters between 30 and 60 cm and 22% of cavity snags having diameters >60 cm. Surface woody fuels increased as snags broke and fell, reaching maximum levels in all size classes 15–20 years after fire. The percentage of large diameter rotten woody fuels increased steadily beginning about 15 years after fire, with implications for fuel management and subsequent wildfire behavior and severity. Our study supports the proposition that fire‐killed snags represent a transient resource pulse in which the relative contribution of snags to different ecological functions varies with snag diameter, species, time since fire, and landscape position.

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Snag longevity of Douglas-fir, western hemlock, and western redcedar from permanent sample plots in coastal British Columbia

Cited by 24 publications

References 32 publications

Natural tree regeneration and coarse woody debris dynamics after a forest fire in the western Cascade Range

Natural tree regeneration and coarse woody debris dynamics after a forest fire in the western Cascade Range

Do larger snags stand longer?—snag longevity in mixed conifer–hardwood forests in Hokkaido, Japan

Snag decomposition following stand‐replacing wildfires alters wildlife habitat use and surface woody fuels through time

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