Postfire population dynamics of a fire-dependent cypress

Brennan, Teresa J.; Keeley, Jon E.

doi:10.1007/s11258-019-00939-8

Cited by 5 publications

(4 citation statements)

References 30 publications

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“…old-growth shrubs), as well as mapping and monitoring of grevillea populations in Warra NP, Mann River Nature Reserve and on private land. The findings of this study have parallels in other international contexts, such as in the US where rare, fire-dependent plants such as the Tecate cypress (Hesperocyparis forbesii) are vulnerable due to immaturity risk and fire-climate interactions that may impact their persistence in a future of climate change and altered fire regimes (Brennan and Keeley 2019).…”

Section: Discussionsupporting

confidence: 67%

Indigenous cultural burning had less impact than wildfire on the threatened Backwater grevillea (

McKemey

Rangers

Patterson

et al. 2021

Int. J. Wildland Fire

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Indigenous self-determination, land rights and caring for Country programs are enabling Indigenous peoples across the world to re-establish customary roles in biodiversity conservation and cultural fire management. In Australia, Indigenous-controlled lands form the majority of the protected area estate, harbour almost 60% of listed threatened species and maintain high levels of biodiversity. This study used cross-cultural (Indigenous and Western academic) methods to monitor the impact of Indigenous cultural burning v. wildfire on the threatened plant, Backwater grevillea (Grevillea scortechinii subsp. sarmentosa). Cultural burning resulted in lower mature grevillea mortality and less impact on reproductive output than wildfire. Both fires stimulated a mass germination but the cultural burn preserved a multi-aged population while the wildfire killed 99.6% of mature shrubs. Comparison of fuel load changes resulting from cultural burning, hazard reduction burning and wildfire indicated that fuel loads were reduced by all fire treatments, although the cultural burn was less severe than other fires. Our case study of the Backwater grevillea and its Banbai custodians provides an example where Indigenous rangers have adopted a plant into their cultural management framework. They are conserving this threatened species using culturally driven, holistic management that is locally focused and supported by cross-cultural knowledge.

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Section: Discussionsupporting

confidence: 67%

Indigenous cultural burning had less impact than wildfire on the threatened Backwater grevillea (

McKemey

Rangers

Patterson

et al. 2021

Int. J. Wildland Fire

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“…Fire was very effective in promoting regeneration within Baker cypress, resulting in an average of 11 seedlings/m 2 among the burned source trees. This estimate was consistent with postfire seedling density of Tecate cypress (H. forbsii) Maximum distance from subject tree (m) Number of observations in southern California, which ranged from 10 to 18 seedlings/m 2 for stands >7 yr old (Brennan and Keeley, 2019). As with other serotinous species (Greene et al, 2013;Brennan and Keeley, 2019), the cones of Baker cypress were essentially emptied of seeds within ~1 yr after the fire, and we did not observe any additional recruitment after the second postfire summer.…”

Section: Discussionsupporting

confidence: 83%

Strong dispersal limitation in postfire regeneration of Baker cypress, a rare serotinous conifer

McNamara

Greene

Kane

2019

American J of Botany

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Dispersal capacity primarily determines the spatial establishment patterns that drive range expansions and contractions in tree species. Seedling establishment in Baker cypress (Hesperocyparis bakeri [(Jeps.) Bartel]) relies predominantly on fire events, due to its cone serotiny, shade intolerance, and small seeds that require the optimal conditions of fire-exposed, mineral soil seedbeds. METHODS:We quantified the density and spatial distribution of post-disturbance seedlings following the 2014 Eiler Fire in northern California and compared the observed recruitment to predictions from a mechanistic seed dispersal model. RESULTS:Postfire recruitment was dense, averaging 11 seedlings/m 2 , and occurred primarily in the first year after fire. We estimated the mean descent velocity of the wingless seeds as ~4 m/s, the highest value reported for any putatively wind-dispersed tree species. The rapid seed descent contributed to markedly spatially constrained recruitment. Most seedlings (~81%) established within 5 m of the parent tree, and 94% established within 10 m. The maximum observed dispersal distance was 48.5 m; dispersal distance scaled linearly with canopy height. Distributions of modeled seed dispersal distance and observed seedling establishment in Baker cypress did not differ, demonstrating that wind disperses seeds a short distance because of the lack of a wing, and secondary dispersal appeared to be minimal at this recently burned site. CONCLUSIONS:If seed dispersal is solely reliant on wind, migration in response to rapid climate change will be impeded and potentially present difficulties in sustaining populations of this and other obligate seeder species with equally constrained dispersal.

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“…Thus, the probability of a fire burning a second time before the stand reaches maturity is likely extremely low, and we are unaware of any population that has experienced such a short-interval fire in Baker cypress; however, recurrent fire within seven years that resulted in no regeneration was recently observed for Tecate cypress (Hesperocyparis forbesii [Jeps.] Bartel) in southern California (Brennan and Keeley 2019).…”

Section: Discussionmentioning

confidence: 99%

Post-fire fuel succession in a rare California, USA, closed-cone conifer

2019

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Background: Increasing frequency and size of wildfires over the past few decades have prompted concerns that populations of obligate seeding species may be vulnerable to repeat, short-interval fires that occur prior to these species reaching maturity. The susceptibility of populations to this risk is partially dependent on the amount and characteristics of fuel loading over time and their influence on fire behavior and effects. This study characterized fuel dynamics and modeled fire behavior across a time-since-fire chronosequence in stands of the rare, serotinous conifer, Baker cypress (Hesperocyparis bakeri [Jeps.] Bartel), ranging in age between 3 and 147 years post fire. Results: Litter and fine woody fuel loading (1-to 100-hour) were highest in the 10-year-old and 147-yearold stands, while coarse fuel loading (1000-hour) peaked in the 10-year-old stand and subsequently decreased with time since fire. Duff loading consistently increased with time since fire. Cone production had not occurred in the first 10 yr of stand development. Foliar moisture content in Baker cypress was inversely correlated with stand age, and older foliage had lower moisture content than younger foliage. Modeled surface fire behavior was highest in the 10-year-old and 107-year-old stands in accordance with higher litter, fine woody fuel, or shrub fuel accumulation. While foliar moisture content was higher in younger stands and influenced the critical fireline intensity, we did not observe changes in fire type. Conclusions: Fine-fuel loading in Baker cypress stands followed a U-shaped pattern over time (first decreasing, then stable, then increasing), consistent with findings in other forests with stand-replacing fire regimes. Our results indicated that early-successional stages of Baker cypress forests have sufficient fuels to allow for the spread of wildfire and 10-year-old stands could burn with substantive fire behavior prior to cone production. Whenever possible, we recommend suppressing wildfire in stands less than 20 yr old to avoid substantial decreases or local extirpation of these rare Baker cypress populations. Our results highlight the importance of knowing the cone production patterns, fuel dynamics, and corresponding fire behavior over the development of obligate-seeder species to assess the risk of population loss due to short-interval fires.

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Postfire population dynamics of a fire-dependent cypress

Cited by 5 publications

References 30 publications

Indigenous cultural burning had less impact than wildfire on the threatened Backwater grevillea (

Indigenous cultural burning had less impact than wildfire on the threatened Backwater grevillea (

Strong dispersal limitation in postfire regeneration of Baker cypress, a rare serotinous conifer

Post-fire fuel succession in a rare California, USA, closed-cone conifer

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