Field Note: Seed Viability and Female Cone Characteristics of Mature Knobcone Pine Trees

Fry, Danny; Stephens, Scott L.

doi:10.5849/wjaf.11-046

Cited by 8 publications

(5 citation statements)

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“…Estimates for knobcone pine suggest the mean cone to seedling conversion ratio is 1:1 (M.C. Agne, unpublished data), equivalent to approximately 60-100 seeds for one established seedling (Fry and Stephens 2013).…”

Section: Discussionmentioning

confidence: 99%

“…Further, our field work occurred in warm and dry weather, so it is unlikely that scale contraction due to high relative humidity (Vogl 1973) caused us to tally open cones as closed cones. We did not directly assess seed density within cones in this study, but previous estimates of seed density within closed cones range from 61-95 mean seeds cone -1 for knobcone pine (Fry and Stephens 2013) and 62-78 mean seeds cone -1 for bishop pine (S.…”

Section: Field Data Collectionmentioning

confidence: 99%

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Demographic processes underpinning post-fire resilience in California closed-cone pine forests: the importance of fire interval, stand structure, and climate

et al. 2022

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The resilience of serotinous obligate-seeding plants to fire may be compromised if increasing fire frequency curtails time available for canopy seed bank accumulation (i.e., immaturity risk), but how various drivers affect seed availability at the time of fire is poorly understood. Using field data from California closed-cone pine (Pinus attenuata and P. muricata) stands, we assess two critical demographic processes during the inter-fire period-reproductive capacity and mortality.At tree-and stand-levels, we test how these processes are affected by stand age and are mediated 2 by biotic and abiotic factors. We found that stand age was the key driver of reproductive capacity; older stands had a greater proportion of reproductively mature individuals and greater closed cone density. Stand density mediated the effect of age; greater stand density resulted in greater closed cone density and a lower proportion of reproductively mature individuals, but reproductive capacity in low-and high-density stands converged over time. Increased moisture stress reduced the stand-level proportion reproductively mature but had no effect on closed cone density. Mortality was strongly associated with density-dependent thinning and increased in stands with high moisture stress. Reproductive capacity began to increase sharply 10 years after fire and by 20 years immaturity risk is low. However, prior to 20 years, low-density stands with high moisture stress may be more susceptible to immaturity risk. Understanding these relationships is critical to predicting serotinous population persistence under changing climate and disturbance conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Field Data Collectionmentioning

confidence: 99%

Demographic processes underpinning post-fire resilience in California closed-cone pine forests: the importance of fire interval, stand structure, and climate

et al. 2022

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“…These categories ignored transitional phases characterized by closed gray cones with some scales already open. Current cones were less than 1 year old, brown cones were estimated to be 1–2 years old since seed ripening, and gray cones were expected to be three or more years old (Fry & Stephens, 2013). For each sampled tree, we estimated the proportion of current, brown, or gray cones, distinguishing between trees with a dbh greater than or less than 10 cm.…”

Section: Methodsmentioning

confidence: 99%

Evaluating immaturity risk in young stands of the serotinous knobcone pine (Pinus attenuata)

Marlin,

Greene,

Kane

et al. 2024

Ecosphere

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As wildfire becomes increasingly frequent, many serotinous plant populations risk local extirpation if fire recurs prior to sufficient seed accumulation in the canopy (i.e., “immaturity risk”). Following two 2018 wildfires in northwestern California, we studied seed viability, cone production, and postfire regeneration of a serotinous conifer, knobcone pine (Pinus attenuata), with stand ages (time since fire) ranging from 6 to 79 years. Cone density per tree was more strongly associated with tree diameter than age, and cone density was positively related to postfire seedling regeneration. Most of the postfire knobcone pine regeneration established during the first year with high survivorship in the following first postfire year. Adjusting for survivorship, the estimated minimum age for knobcone pine to promote self‐replacement (one recruit per tree) was 9.5 years (or 4.6‐cm dbh) and the probability of reburning at the modern fire rotation of 43 years was 19.8%. Based on our results, we found that immaturity risk was currently low for knobcone pine. Our approach provides a quantitative method to assess immaturity risk in knobcone pine and other serotinous conifer species that can be used to evaluate future risk under rapidly changing climate and fire conditions.

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“…We hypothesized that: (1) trees would become reproductively mature at a young age; (2) seed density would increase with time since re, as trees slowly accumulated cones with more, higher viability seeds; and (3) the degree of pine pitch canker infection would be greatest in relatively small trees, consistent with ndings from related species. Although previous studies of serotinous species have estimated canopy seedbank development as a function of cone production and stand density (Keeley et al 1999, Turner et al 2007, Fry and Stephens 2013, Agne et al 2022, this is the rst to additionally quantify both seed viability and density over a range of stand ages to enumerate a more accurate assessment of reproductive capacity and the temporal window of re return promoting forest resilience. We use the results to discuss options for developing pyrosilvicuture as a component of management in re-obligate, crown-re adapted forest types, such as serotinous bishop pine.…”

Section: Al 2021)mentioning

confidence: 99%

Rapid viable seedbank fosters resilience via pyrosilviculture in serotinous bishop pine

Bisbing

Urza

York

et al. 2022

Preprint

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Background In ecosystems where fire has been excluded, pyrosilviculture can restore fire regimes while mitigating risk where fire is inevitable. Pyrosilviculture in crown fire-adapted forests is, however, limited by insight into the temporal window of fire return matching canopy seedbank development. Here, we characterized demographic responses to fire and non-native pine pitch canker infection in a chronosequence of serotinous bishop pine stands burned at high-severity to quantify: (1) temporal patterns of seedbank development given seed viability and density, cone production, and tree density, and (2) pine pitch canker incidence across tree ages and sizes to assess how infection might influence pyrosilviculture. Stands were burned to promote resilience while mitigating WUI wildfire, and we use to our findings to elucidate pyrosilvicuture as a means of meeting these objectives in crown-fire adapted forests. Results Bishop pine produces an abundant, viable seedbank within six years, with high production and viability persisting across developmental stages and age classes. Seed abundance and viability are exceptionally high at even the earliest age (median > 600,000 seeds ha− 1 & 97% viability at 6 years) and remain high, with the oldest stands (36 years) maintaining median densities of > 500,000 seeds ha− 1 and viability of 95%. We additionally learned that pine pitch canker infection is most severe during the sapling stage (8–10 years post-fire), potentially shifting the timing and development of fuel structure to earlier successional stages as well as limiting recruitment into the canopy. Conclusions In bishop pine and equally-fecund serotinous species, burning at short fire return intervals is feasible given early development of a robust, viable seedbank, addressing two common management challenges in fire-adapted forests - restoring fire to promote resilience while mitigating wildfire risk to the WUI. Moreover, frequent fire in pine pitch canker infected stands may also provide disease mitigation. Although the long-term effects of pine pitch canker infection remain unknown, bishop pines’ viable and persistent seedbank suggests that managers can ignite prescribed fire across a broad return interval – as short as six to eight years and as long as several decades – to promote ongoing bishop pine resilience, mitigate disease infection rates, and reduce wildfire risk in WUI-adjacent ecosystems.

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Field Note: Seed Viability and Female Cone Characteristics of Mature Knobcone Pine Trees

Cited by 8 publications

References 0 publications

Demographic processes underpinning post-fire resilience in California closed-cone pine forests: the importance of fire interval, stand structure, and climate

Demographic processes underpinning post-fire resilience in California closed-cone pine forests: the importance of fire interval, stand structure, and climate

Evaluating immaturity risk in young stands of the serotinous knobcone pine (Pinus attenuata)

Rapid viable seedbank fosters resilience via pyrosilviculture in serotinous bishop pine

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