Complex Effects of High Severity Fire on a Serotinous Conifer

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Merriam, Kirsten M. Bovee This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7384282/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Apr, 2026 Read the published version in Fire Ecology → Version 1 posted 10 You are reading this latest preprint version Abstract Background Baker cypress ( Hesperocyparis bakeri (Jeps.) Bartel) is a serotinous conifer associated with high severity fire regimes. Until recently, observations of wildfire effects to Baker cypress populations were rare. There was little direct evidence of fire effects on germination immediately after fires or on population dynamics over longer time frames. We sampled four Baker cypress populations that burned in wildfires between 2006 and 2017 to evaluate postfire germination. We continued data collection at two sites and established a third experimental site to identify factors that contribute to the survival, growth, and health of Baker cypress seedlings over time. Results Although Baker cypress is associated with high severity fire regimes, we found that the effects of fire severity were complex and included both positive and negative, as well as short and long-term effects. Germination rates were positively related to crown scorch, but negatively affected by char bole height. These findings suggest that while Baker cypress requires heat to open cones, there are limits to the temperature or duration of heat that seeds can tolerate. Although high severity fire is thought to be necessary to create environmental conditions necessary for germination, we found that ground cover variables were not significant predictors of postfire germination rates at our study sites. Over longer time frames (9–10 years), Baker cypress density, survival, growth, and health were significantly impacted by fire severity and its effect on environmental variables, including overstory canopy closure, rock cover and shrub cover, demonstrating that fire severity has persistent legacy effects on Baker cypress populations. Conclusions In an era of altered fire regimes, optimizing fire effects to achieve sufficient crown scorch while minimizing fire behavior that causes extensive bole char may help ensure the persistence of Baker cypress populations into the future. This kind of nuanced understanding of the effect of fire on Baker cypress would not have been possible without immediate postfire assessments of fire severity that were not possible until recently. Baker cypress fire severity immaturity risk postfire regeneration Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 BACKGROUND Species in fire adapted ecosystems possess traits that allow them to persist and benefit from specific fire regimes (Keeley and Pausas 2022, Lamont 2022). These fire regimes are often broadly characterized in terms of severity and frequency (Tolk et al. 2023). For vegetation types associated with frequent, low severity fire regimes, studying the relationship between species traits and fire effects is relatively straightforward because fires occur often and most species survive, allowing for frequent and detailed observations of species responses to fire (Agee 1993, Van Wagtendonk 2018). However, in vegetation types associated with high severity fire regimes, direct evidence of fire effects is often lacking because fires occur very infrequently, most individuals are killed by fires, and postfire environments are often dramatically altered (Van Wagtendonk 2018). As a result, the response of vegetation to infrequent, high severity fire regimes is often inferred from indirect evidence, such as the age of cohorts or species traits (Pausas et al. 2004, Pausas et al. 2017). Although high severity fire effects can be inferred from even-aged cohorts, metrics such as crown scorch or bole char height that can inform a more nuanced understanding of high severity fire effects are often only apparent for short periods after fires. Similarly, fire severity metrics that assess ground cover variables are often difficult to discern after extended periods of time. Although we may know that species are associated with high severity fire regimes, without immediate postfire observations, we may not fully understand how fire behavior affects species and postfire environmental conditions over both short and long time frames (Tada et al. 2024). Baker cypress ( Hesperocyparis bakeri (Jeps.) Bartel) is a serotinous conifer associated with high severity fire regimes (Barbour 2007, Vogl et al. 1977). Baker cypress occurs in 11 widely scattered locations across northern California and southern Oregon. It is the northernmost naturally occurring cypress in the world, found at elevations of up to 2100 m where it grows among high-elevation conifers such as red fir ( Abies magnifica A. Murray bis) and western white pine ( Pinus monticola Douglas ex D. Don). Baker cypress has closed cones, considered an adaptation to high intensity fires because heat is necessary to open cones and release seeds (Barbour 2007, Lamont 2022, Pausas et al. 2004). Baker cypress possess other traits associated with high severity fire, including retaining numerous dead lower branches, growing in dense stands, and having thin, papery bark that is highly flammable (Pausas et al. 2017, Schwilk and Ackerly 2001). Baker cypress generally occur in even aged cohorts, indicating that the parent generation experienced complete mortality after a high severity fire. Baker cypress is thought to require high severity fire in order to create favorable postfire conditions for germination and seedling survival such as high light availability and exposed bare mineral soil (Keeley and Zedler 1998, Lamont et al. 1991, Vogl et al. 1977). Most species of cypress are poor competitors and postfire recruitment may require high severity fire to reduce competition by killing the dormant seeds of other species (Keeley and Zedler 1998, Shi et al. 2022). Until recently, observations of wildfire effects to Baker cypress populations were rare. There was little direct evidence of fire effects on cone opening and germination immediately after fires or information about how environmental characteristics affected by fires influence population dynamics over longer time frames. Understanding how fire affects Baker cypress populations has become more urgent as natural fire regimes have become fundamentally altered over the past century. Baker cypress is sensitive to fire return interval because the primary seed source for postfire regeneration comes from seeds accumulated inside cones and the time between fires determines the size of this canopy seed bank (Bliss and Zedler 1997, Keeley et al. 1999, Lamont and Enright 2000, Pausas et al. 2004). Until recently, the primary threat to Baker cypress was fire suppression. A 2006 status survey of Baker cypress found that fire had been excluded from six of the 11 known populations for 100 years or longer (Rentz and Merriam 2009). Mature adult cypress in several populations were dying as a result of interspecific competition in areas that had experienced prolonged fire exclusion, with no evidence of regeneration (Keeler-Wolf 2004). If fire return intervals exceed the lifespan of the trees or the longevity of the seeds stored in the canopy, cypress and other closed cone conifers can die before they reproduce (Keeley et al. 1999, Keeley and Fotheringham 2000, Lamont 1991,Zedler 1995). A more recent and emerging threat to Baker cypress is too frequent fire. The extent and frequency of wildfires has increased dramatically across the western US (Iglesias et al. 2022, Juang et al. 2022, Westerling 2016) and seven of the 11 Baker cypress populations have burned in wildfires over the past 20 years. Baker cypress do not begin producing ovulate cones until the trees are at least 14 years of age or older, and these cones require two years to mature (Armstrong 1980). In addition, seed viability and germination rates among California cypress can be quite low, extending the amount of time required for populations to store enough seed to replace the parent population (Zedler 1977). Minimum fire return intervals in vegetation dominated by California cypress is estimated to be 30 years, while mean fire return intervals are estimated at 55 years (Van de Water and Safford 2011). Climate change and associated stressors may be lengthening the amount of time needed for populations to achieve sufficient canopy seed storage as warmer, drier conditions may reduce the cone production rates of stressed trees and result in higher mortality rates (Enright et al. 2015). One Baker cypress population was almost completely extirpated by successive fires that burned before seedlings could produce cones, and six of the remaining ten Baker cypress populations are now completely or partially comprised of immature seedlings. These populations are at risk of extirpation if they burn again before these trees can produce cones (Agne et al. 2022, Brennan and Keeley 2019, de Gouvenain and Ansary 2006, Keeley et al. 1999, Lamont and Enright 2000, Ne'eman et al. 1999, Rodríguez‐Buriticá and Suding 2013, Wuenschel et al. 2023, Zedler 1977). Although the recent dramatic increase in the number and frequency of fires pose a significant threat to Baker cypress, it also provides a unique opportunity to evaluate in more detail how fire affects populations both in the short term, through direct effects on germination, and over longer time frames by influencing environmental variables associated with survival, growth, and health. Determining what factors promote Baker cypress germination, survival, growth, and health is critical for developing management recommendations and conservation strategies that will ensure the persistence of this and other closed cone conifer species in an era of altered fire regimes and changing climates (Agne et al. 2022). Study Objectives We sampled four Baker cypress populations that burned in wildfires between 2006 and 2017 to evaluate postfire germination. We continued data collection at two sites and established a third experimental site to identify factors that contribute to the survival, growth, and health of Baker cypress seedlings over time. Our study was designed to answer the following questions: What factors promote postfire regeneration of Baker cypress? How did fire severity influence longer-term survival and growth of Baker cypress seedlings over time? What environmental factors influence longer-term density, survival, growth, and health of Baker cypress seedlings, and how were these variables affected by fire severity? METHODS Baker cypress occurs in 11 widely scattered locations across the northern Sierra Nevada, Cascade, and Siskiyou Mountains (Figure 1). The Siskiyou occurrences are found on serpentine and granitic soils, while in the Sierra Nevada and Cascade ranges Baker cypress is found on volcanic substrates. Baker cypress occurs at elevations from 1157 to 2146 feet on north to northeast facing slopes and is associated with chaparral, mixed evergreen and montane coniferous forest vegetation types (Wolf 1948). Baker cypress can grow over 30 m tall with trunks of up to 1.5 m in diameter. Baker cypress is found primarily on public lands managed by the USDA Forest Service and the USDI Bureau of Land Management. For this study, we focused on populations distributed broadly across the species range that burned in wildfires between 2006 and 2017, including: 1) the Independence site (Siskiyou) that burned in the 2006 Titus Fire; 2) the Mud Lake site (Sierra Nevada) that burned during the 2007 Moonlight Fire; 3) the Lassen site (Cascades) that burned during the 2014 Eiler Fire; and 4) the Seiad site (Siskiyou) that burned during the 2017 Miller Complex Fire (Table 1). Prefire stand conditions Prefire stand conditions were assessed as part of a range-wide survey of Baker cypress conducted in 2006 (Rentz and Merriam 2009). Between three and 15 809.4 m 2 circular plots were randomly established at each location depending on accessibility, size, and distribution of the Baker cypress stand. Within each plot we recorded species, diameter at breast height (dbh), height, and status (live vs. dead) for all trees (dbh >10.16 cm) and saplings (dbh 1.37 meter). We measured seedling density using eight 1 m 2 quadrat frames placed systematically along transects radiating in the four cardinal directions from plot center. Within each 1 m 2 quadrat we recorded the number and species of all tree seedlings (height < 1.37 m) as well as the percent cover of shrubs, herbs and ground cover variables including litter, rock, and bare ground. Litter depth was measured at each 1-m 2 quadrat and a spherical densiometer was used to measure overstory canopy closure. To determine tree age, we collected core samples from six Baker cypress individuals representing the entire range of size classes present. Cores were collected at the lowest possible location along the bole using an increment borer. To calculate canopy seed storage, we estimated the number of cones on each Baker cypress tree and the percentage of closed cones. We then collected ten cones each from the same six trees sampled to determine tree age. We counted the number of fully developed and underdeveloped seeds present in each cone and tested a sample of 20 fully developed seeds by exposing them to a tetrazolium staining agent (Peters 2000). The number of viable seeds per tree was then calculated based on the following formula: Number of viable seeds/tree (canopy seed storage/tree) = # of seeds/cone x % viability x # of cones/tree x % closed cones/tree Plot level estimates of canopy seed storage were then made by multiplying the average number of viable seeds tree -1 by the number of trees in each plot. Postfire germination To understand factors that influenced the immediate (i.e., first growing season) postfire germination of Baker cypress, we repeated the prefire sampling methods at our four study sites. In addition to prefire stand condition data, we recorded postfire indicators of severity, including scorch height, bole char height, percent crown scorch andtorch, and mortality of all trees within the larger plot. We also estimated overall fire severity at the 1 m 2 quadrat scale using a categorical system that includes both soil and vegetation factors developed by the US Department of the Interior (2003). Low severity plots were characterized by scorched to lightly burned vegetation and substrates, while high severity plots were characterized by moderately to heavily burned vegetation and substrates. We chose this categorical metric because it includes a broad suite of variables associated with fire severity that can be readily determined in the field and is easily interpreted by managers. Postfire seedling survival, growth and health To evaluate longer-term postfire seedling survival, growth, and health we continued our data collection efforts for nine years at the Lassen study site, and ten years at the Mud Lake study site (Table 2). We repeated measures of data collected at the 1 m 2 quadrat scale (vegetation cover, ground cover, tree seedling species and number, duff and litter depth, and overstory canopy closure). Within each quadrat, we randomly selected five Baker cypress seedlings, and for each measured its height and evaluated its health status on a categorical scale of zero to four (0 = dead, 1 = no new growth, 2 = less than 5 cm new growth and some dying parts, 3 = more than 5 cm of new growth and some dying parts, 4 = more than 5 cm of growth and no dying parts). Planting experiment We conducted an additional experiment to specifically investigate the effects of shrub cover and overstory canopy closure on Baker cypress seedling survival, growth, and health. In 2008, we planted 58 one-year old nursery grown seedlings in 16 1 m 2 plots adjacent to the Mud Lake site in areas that had burned during the 2007 Moonlight Fire. Seedlings were planted where levels of shrub cover and overstory canopy closure naturally differed (Table 2). We established four replicates for each combination of shrub cover and canopy closure. Data was collected as described for the postfire seedling survival, growth, and health sampling above, including seedling height and health status, vegetation and ground cover, litter depth, and overstory canopy closure. Plots were resampled in 2009, 2010, 2012 and 2015. Statistical Analyses Generalized linear mixed models were used to identify factors that influenced postfire germination rates as well as longer-term trends in seedling growth, health, and survival over time. Our evaluation of longer-term trends focused on differences between high and low severity fire effects A random effects term defined for each nested plot and site combination was included in all models to account for potential differences in response variables due to site identity and to the repeated measures of plots in some analyses. Full models that included all predictor variables were fit using maximum likelihood with the lme4 package in R version 4.3.1 (Bolker et al. 2009, Bates et al. 2015, R Core Team 2025). We then performed backward elimination of non-significant effects with the LmerTest package (Kuznetsova et al. 2017). The relative contributions of fixed and random effects were estimated by calculating marginal and conditional pseudo-R values for each model (Nakagawa and Schielzeth 2013) with the MuMin package (Barton and Barton 2015). To test for the effects of canopy closure and shrub cover in our planting experiment on Baker cypress seedling growth, health, and survival we used repeated measures ANOVA (Girden 1992) with the rstatix package in R version 4.3.1(Kassambara 2023, R Core Team 2025) with time (year) specified as the within-subjects factor. Significant interactions between factors were evaluated using pairwise paired t-tests between the levels of the within-subjects factor and P values were adjusted using the Bonferroni multiple testing correction method. RESULTS Prefire stand conditions and postfire germination Mean prefire stand ages at our study sites ranged from 56 to 135 years (Table 3). Canopy seed storage was high, ranging from over 350,000 viable seeds plot -1 at Lassen to just over 50,000 viable seeds plot -1 at Mud Lake (Table 3). Mean postfire germination in our study plots was also high, averaging 6.3 seedlings m -2 ( + 1.2) or 63,173 ( + 1200) seedlings ha -2 . First-year seedling density, averaging 870 ( + 451) seedlings per parent tree ,was well above that necessary to replace the parent population at all of our study sites. Scorch height and char bole height were the most significant predictors of Baker cypress germination rates and together explained 45% of the variation in first-year seedling density (Figure 2). Seedling density one year postfire was positively influenced by the maximum height of scorch (F 1,29 = 24.8, P < 0.001). For every 1 m increase in scorch height, an additional 1.9 seedlings m -2 germinated. On the other hand, maximum char height negatively influenced germination (F 1,29 = 18.7, P < 0.001), for every 1 m of char height, seedling density declined by 1.4 seedlings m -2 . Other variables, including ground cover characteristics and prefire canopy seed storage, were not related to postfire germination rates. Long-term seedling survival, growth, and health Fire severity was a significant predictor of seedling density, survival, and health, but not of seedling height in the final year of sampling (nine years postfire at the Mud Lake site and ten years postfire at the Lassen site; Figure 3). Fire severity explained 22% of the variation in seedling densities among plots in the final year of sampling (F 1,25 = 7.47, P = 0.01, R 2 m = 0.22, R 2 c = 0.22 ). High severity plots had an estimated mean density of 7.3 seedlings m -2 , which was more than triple the estimated density of 2.2 seedlings m -2 in low severity plots. Long-term survival of first year germinants was estimated to be twice as high in high severity plots (76%) versus low severity plots (38%) at the final year of sampling (F 1,23 = 9.83, P = 0.004, R 2 m = 0.27, R 2 c = 0.32). Seedling health also varied by fire severity, with higher estimated health scores of 3.7 in high severity plots and 3.2 in low severity plots (F 1,24 = 6.69, P = 0.02, R 2 m = 0.21, R 2 c = 0.21). These health scores indicated a condition that is intermediate between health class 3 (healthy) and Health Category 4 (very healthy). Estimated seedling height, by contrast, was not significantly different between high and low severity plots in the final year of sampling (F 1,23 = 0.36, P = 0.55, R 2 m = 0.01, R 2 c = 0.07). Environmental predictors of seedling survival and growth Canopy closure and ground cover variables were not significant predictors of seedling density or health. However, canopy closure, shrub cover, and rock cover were found to be significant predictors of seedling height and survival (Table 4). Coarse woody debris, bare ground cover, herbaceous cover, moss cover, and litter and duff depth did not contribute to best-fit models for any of the seedling attributes. In the final year of sampling (10 years postfire at Mud Lake, 9 years postfire at Lassen), average seedling height was negatively associated with both canopy closure (F 1,22 = 6.51, P = 0.02), and with shrub cover (F 1,23 = 4.09, P = 0.05). Twenty-eight percent of the variation in seedling height was explained by these environmental factors. Seedling height was predicted to be 6 cm shorter for every 10% increase in canopy closure, and 1 cm shorter for every 10% increase in shrub cover. The percentage of first-year germinants surviving to the final year of sampling was negatively associated with canopy closure (F 1,22 = 9.70, P <0.01), but positively associated with both shrub cover (F 1,22 = 8.65, P <0.01) and with rock cover (F 1,22 = 9.28, P <0.01). A 10% increase in canopy closure predicted a 9% decrease in survival, while a 10% increase in shrub cover predicted a 5% increase in survival. A 10% increase in rock cover predicted a 17% increase in survival. Fire effects to the growing environment The growing environment for Baker cypress seedlings at the Lassen and Mud Lake study sites was dynamic, varying with both time since fire and fire severity (Figure 4). Canopy closure was on average 39% higher in lower severity plots (F 1,74 = 4.36, P = 0.04) but decreased over time in both high and low severity plots (F 1,90 = 75.84, P < 0.0001). Time since fire and fire severity explained 30% of the variation in canopy closure among plots, while the effect of site and plot explained an additional 41% of this variation (R 2 m = 0.30, R 2 c = 0.71). Shrub cover increased over time in both high and low severity plots, however this increase occurred at a significantly greater rate in high severity plots (F 1,105 = 5.01, P = 0.03). Rock cover was on average three times higher in high severity plots (F 1,51 = 8.24, P < 0.01) and decreased over time in both high and low severity plots (R 2 m = 0.16, R 2 c = 0.47). Together, time since fire and fire severity explained 22% of the variation in shrub cover between plots (R 2 m = 0.22, R 2 c = 0.65) and 16% of the variation in rock cover between plots (R 2 m = 0.16, R 2 c = 0.47). Planting experiment In our planting experiment that evaluated the effects of shrub cover and overstory canopy closure on the growth, health, and survival of planted Baker cypress seedlings, we observed a significant interaction effect between years since planting and seedling height (F 3,56 = 7.4, P = 0.0003). All seedlings were taller three and five years after planting, but significantly higher where canopy closure was low (Figure 5). The health status of seedlings was not associated with year or canopy closure, but was significantly higher when seedlings were grown in association with shrubs (F 1,62 = 11, P = 0.002, Figure 6). Mortality rates increased significantly from less than 1% in the first two years after to planting, to over 25% mortality after 7 years (F 3,45 = 10, P = 0.0004). However, mortality was not associated with shrub cover or overstory canopy closure in our planting experiment. DISCUSSION Postfire germination We found that fire severity was the most important driver of Baker cypress germination. However, the relationship between fire severity and germination was more complex than we predicted and included both positive and negative effects. Scorch height was positively related to postfire germination, likely because heat is required to open serotinous cones and release seeds stored in the canopy (Enright and Lamont 1989 , Habrouk et al. 1999 , Vogl et al. 1977 ). Milich et al. ( 2012 ) found that Baker cypress cones opened when heated to 500°C. Higher scorch heights indicate fire effects that extend into the canopy and result in scorching of needles without reaching temperatures or durations of heating that result in needle defoliation (Alexander and Cruz 2012 , Ryan and Noste 1985 , Ryan 2002 , Turner et al. 1994 ).. Conversely, we found that seedling densities declined as tree bole char height increased. Charring of the tree bole can indicate higher fire intensity and longer duration of exposure than scorch (Alexander and Cruz 2012 , Ryan and Noste 1985 , Ryan 2002 , Turner et al. 1994 ,). Although cypress require relatively high temperatures for cone opening (i.e., 500°C), Milich et al. ( 2012 ) found that Baker cypress seed viability was negatively affected by longer heating durations and no germination was observed in seeds exposed to heat for more than two minutes, regardless of temperature. This suggests that Baker cypress may be adapted to faster moving crown fires, which would allow cones stored in the tree canopy to be heated to sufficient temperatures to open and release seeds, without being exposed to these temperatures for extended periods. Brennan and Keeley ( 2019 ) found lower germination rates of Tecate cypress ( Hesperocyparis forbesii (Jeps.) Bartel) in areas where fire severity was high, and studies of other serotinous species have also found that longer durations of heating reduced seed survival (Alexander and Cruz 2012 , Habrouk et al. 1999 ,Tada et al. 2024 ). Extensive charring of the tree bole may be a result of fire suppression, where an accumulation of surface fuels can result in higher fire intensity and longer residence times (Agee and Skinner 2005 , Alexander and Cruz 2012 , Brodie et al. 2024 , Keane 2014 ). None of our four study sites had previously burned in recorded history, and all were heavily encroached by other species of conifer. Previous authors have suggested that cypress require high severity fire not only to open serotinous cones, but also to prepare a receptive seed bed of bare mineral soil conducive for germination (Barbour 2007 , Vogl et al. 1977 ). However, we found that ground cover variables were not significant predictors of postfire germination rates at our study sites. Instead, the effects of fire severity on tree-level variables related to cone opening and seed dispersal were more important than fire-related changes to ground cover. This suggests that seed availability, mediated by fire intensity, was the primary driver of postfire germination in our Baker cypress populations. It was surprising that prefire canopy seed storage was not a significant predictor of postfire germination at our study sites. However, the mean age of the Baker cypress we evaluated was between 56 and 135 years, giving these populations sufficient time to accumulate cones and develop robust canopy seed banks. The mean number of viable seeds available in the canopy of trees in our study plots was almost 200,000, suggesting that seed availability was not a limiting factor. However, fires that occursin younger stands, that have not had time to develop a sufficient canopy seed bank, pose a serious threat to all cypress species in California (Agne et al. 2022 , Brennan and Keeley 2019 , de Gouvenain and Ansary 2006 ,, Keeley et al. 1999 , Ne'eman et al. 1999 , Wuenschel et al. 2023 , Zedler 1977 ). Long-term seedling survival, growth, and health We found that fire severity not only determined germination rates, but also had longer-term implications for Baker cypress seedling survival, growth, and health. Seedling density, survival, and health were all higher after nine or ten years in plots that burned at high severity, while seedling height did not differ between high and low severity plots. It is likely that these longer-term effects resulted from fire effects to the postfire growing environment for seedlings, including the negative effects of canopy closure in low severity plots, and the positive effects of nurse objects such as rocks and shrubs that were promoted by high severity fire. These effects are consistent with studies of post-fire recruitment for other conifer species. Owen et al. ( 2020 ) also found that high severity fire promoted environmental conditions, including understory plant and coarse wood cover, that benefitted ponderosa pine ( Pinus ponderosa Douglas ex Lawson & C. Lawson) seedling growth 11–16 years after the fire. Similar to the patterns we observed in postfire germination, many ground cover variables were not associated with seedling survival, growth, or health at our study sites. This suggests that where canopy seed storage is sufficient to promote germination, established cypress seedlings are not strongly influenced by other herbaceous species or by ground cover variables such as litter. Canopy closure Areas that burned at high severity were characterized by lower canopy closure, which was negatively associated with seedling growth and survival. More trees were killed by high severity fire effects that reduced or eliminated overstory shade from tree crowns, increasing light availability to cypress seedlings. Observations of mature trees have indicated that Baker cypress is a poor competitor and experiences significant mortality when overtopped by other species; our study indicates that seedlings similarly require high light environments (Keeler-Wolf 2004 ). Mallek ( 2009 ) found that McNab cypress ( Hesperocyparis macnabiana (A. Murray bis) Bartel) seedlings experience complete mortality under closed canopy conditions. Many species associated with high severity fire regimes thrive in open conditions (Bond et al. 2012 ) The high amounts of overstory shade at our study sites may be a result of fire suppression, as these populations of Baker cypress had become heavily encroached by other conifer species prior to burning. For example, the Mud Lake site had total tree densities of 563 (+- 40) trees acre − 1 and only 17% of the trees present were Baker cypress. Similarly, Baker cypress represented only 55, 47, at 49% of stand densities at the Seiad, Independence and Lassen study sites, respectively. The high stand densities resulting from fire suppression and conifer encroachment contributed to increased overstory canopy from snags after fires that negatively affected Baker cypress seedlings. High snag densities also contribute to increased fuel loads that put immature populations at increased risk of fires occurring before the new cohort produces cones (Coppoletta et al. 2016 ). Shrub cover We found that shrub cover promoted seedling health in our planting experiment and long-term seedling survival in our natural populations. Shrubs can promote the establishment, survival and growth of tree species, particularly in arid environments (Legras et al. 2010 , Gómez-Aparicio et al. 2004 , Bustamante-Sánchez et al. 2011 , Rolo et al. 2013 , van Zonneveld et al. 2012 ). Shrubs can provide shade that reduces reduce solar radiation and moderate microclimate extremes, leading to a reduction of water stress and evapotranspirative demand (Davis et al. 2019 , Crockett and Hurteau 2022 , Gray and Spies 1997 , Gray et al. 2005 , Holmgren et al. 1997 ). In the southwestern United States, Crockett and Hurteau ( 2022 ) concluded that postfire planting might be delayed until shrubs have established because they can increase postfire planting success. Shrubs also play an important role in promoting soil nutrients and providing protection from herbivory, trampling, and other disturbances (Gómez‐Aparicio et al. 2005, Legras et al. 2010 , Loayza et al. 2017 ). As annual snowpacks decline as a result of climate change, shrubs may also provide thermal protection from frost (Inouye 2000 ). This protection might increase the survival of Baker cypress, a species found at the highest elevation and most northern sites of any cypress species in California, where populations are exposed to extreme cold. Rock cover We found that that rock cover, higher in plots that burned at high severity, promoted Baker cypress seedling survival. High severity fire is effective at removing vegetation as well as duff and litter layers that can obscure rocks in long unburned landscapes. Rocks can create sheltered microsites that benefit seedlings by decreasing soil and air temperatures, increasing soil moisture, and protecting seedlings from other stressors such as herbivory and trampling (Shemesh 2025 ). Rock cover can also limit the space available for competitor species (Alvarez-Yepiz et al. 2014 ). Although some studies have found that facilitation by nurse plants can provide more benefits to seedlings than rocks because they increase soil nutrient availability (Loayza et al. 2017 ), we found that rocks had a greater positive effect on seedling survival than shrubs and seedlings had slower growth rates in plots with higher shrub cover. Other studies have found that rocks can be more effective nurse objects than shrubs or other plant species because they do not limit light availability or compete with seedlings for soil resources (Mlambo and Chiparange 2021 ). Drought The apparent facilitative effect of shrubs and rocks on Baker cypress seedlings may be surprising given that our study populations do not occur in extremely arid environments where these types of effects are frequently observed (e.g., (Gómez-Aparicio et al. 2004 , Shemesh 2025 ). However, other California and Arizona cypress populations have demonstrated sensitivity to drought, (Goforth 2009 , Verrier 2022 , Wuenschel et al. 2023 ) and our study focused on postfire environments that are generally characterized by open, dry conditions often associated with postfire regeneration failure (Davis, et al. 2019 , Dobrowski et al. 2015 , Rodman et al. 2020 ). For serotinous conifers where seed availability is not limited, high severity fires may create conditions that are beneficial for seedlings by increasing the abundance of nurse objects such as rocks, coarse wood, and shrubs (Kuenzi et al. 2008 , Owen et al. 2020 , Shive et al. 2013 ). Survival One of the strongest effects of fire severity we observed was on seedling survival. Even ten years after fire, 76% of seedlings that germinated in areas that burned at high severity survived, while only 38% of seedlings were still alive in areas that burned at low severity. High seedling survival rates contribute to higher densities of adult trees, which can benefit cypress populations by promoting high severity fire effects (Pausas et al. 2017 ), as well as by increasing stand level canopy seed storage that is critical for postfire regeneration (Harvey and Holzman 2014 , Moya et al. 2007 , Turner et al. 2007 , Verkaik and Espelta 2006 ). Higher density stands may also increase the rate at which populations reach reproductive maturity. Agne et al. ( 2022 ) found that knob cone pine ( Pinus attenuata Lemmon) in high-density stands had a ~ 40% greater probability of reaching reproductive maturity than trees in low density stands at an age of ten years. Rapid development of a large canopy seed bank is a critical resilience mechanism to short-interval fires, particularly if warming and drying conditions create an opposing ‘interval squeeze’ effect by increasing mortality rates and reducing cone production between fires (e.g., Enright et al. 2015 ). Nine to ten years postfire our study plots still supported cypress densities that were well above that necessary to replace the parent generation, regardless of severity. In older stands of cypress where seed availability is not limiting, postfire germination rates are likely to exceed the replacement threshold as long as fire severity is sufficient to open cones and disperse seeds while not reaching lethal temperatures or durations. While the Mud Lake (135 years old) and Lassen (56 years old) populations were old enough to have amassed adequate seed storage, recruitment may be below replacement thresholds in younger stands with less canopy seed storage. A number of other studies have found that immature and young stands of cypress are significantly threatened by repeated fire (Agne et al. 2022 , Brennan and Keeley 2019 , de Gouvenain and Ansary 2006 , Keeley et al. 1999 , Ne'eman et al. 1999 , Rodríguez-Buriticá and Suding 2013 , Wuenschel et al. 2023 , Zedler 1977 ). In 2021, four years after the last seedling data was collected at our Mud Lake study site, a second wildfire burned through the Baker cypress population and killed over 99% of the young trees before they had produced cones. CONCLUSIONS Although Baker cypress has long been associated with high severity fire regimes, we found that the effects of fire severity are complex and include both positive and negative, as well as short and long-term effects. The positive effects of crown scorch coupled with the negative effects of char bole height suggest that while Baker cypress requires heat to open cones, there are limits to the temperature or duration of heat that seeds stored in the canopy can tolerate. This nuanced understanding of the effect of fire on Baker cypress would not have been possible without immediate postfire assessments of fire severity following recent wildfires. Fire severity effects on ground cover and overstory canopy closure were not important determinants of germination rates, perhaps because the populations we studied all had large amounts of canopy seed storage and seed availability was not limiting. However, over longer time frames, Baker cypress density, survival, health and growth were significantly impacted by fire severity and its effects on environmental variables, including overstory canopy closure, rock cover and shrub cover. Although canopy seed storage and cone opening appeared to be the main driver of Baker cypress germination rates, variables associated with increased light availability and drought stress refugia were important for the longer term density, survival, health, or height of Baker cypress seedlings. These effects were evident even nine or ten years after fires, demonstrating that fire severity has persistent long-term effects on Baker cypress populations. In an era of altered fire regimes and rapidly changing climatic conditions, optimizing fire effects to achieve sufficient crown scorch while minimizing fire behavior that causes extensive bole char may help ensure the persistence of Baker cypress populations into the future. Prescribed or managed fire in Baker cypress stands must promote crown fire effects to open cones, while avoiding sustained or persistent burning. Adverse fire effects, such as extensive bole charring, may occur where surface fuel loading is high or where pile burning occurs near Baker cypress trees. Reduction of surface fuels in mature stands may help to reduce fire intensity during wildfires, but reduction of ladder fuels or thinning of stands may have unintended negative effects if these actions lower the probability of canopy scorching. Low severity fire will likely not be effective at opening cones, whereas fire intensity that results in extensive bole charring may have lethal effects to seeds. Stand management following wildfire should promote long-term cypress seedling survival to ensure sufficient canopy seed storage prior to subsequent fires. Postfire salvage logging may help to reduce snag densities and provide open conditions for seedlings while also reducing fuel loads to protect immature populations from subsequent fires. When actively planting Baker cypress seedlings, either to reintroduce extirpated populations or to supplement natural regeneration, selecting open sites and using rocks and shrubs as nurse objects could promote the survival of the planted seedlings. The greatest threat to Baker cypress and other California cypress species is shortened fire return intervals, so efforts to reduce fuel loads and to effectively deploy suppression tactics around immature populations is critical to the persistence of these iconic fire adapted species into the future. Declarations The authors declare that they have no competing interests. Author Contribution KM developed prefire sampling design at all study sites and postfire sampling design at Seiad, Independence, and Mud Lake study sites. KM and KB collaborated on postfire monitoring design at Lassen study site and on all statistical analyses. KM wrote the majority of the manuscript and KB contributed substantially to revisions. Acknowledgement This project was partially funded by the Joint Fire Science Program (Project ID Number: 06-2-1-17) with cooperation from the USDA Forest Service. We would like to thank Erin Rentz, Max Creasy, and numerous field assistants and resource specialists from the USDA Forest Service and DOI Bureau of Land Management for their help with this project Data Availability The data used to draw conclusions in this paper are currently in use by the authors and will be published in their entirety simultaneous with the final in-progress publication. Until that time, the data may be accessed upon request from the corresponding author. References Agee, J. 1993. Fire ecology of Pacific Northwest forests. Washington D.C., USA: Island Press. 497 p. Agee, J.K. and Skinner, C.N. 2005. Basic principles of forest fuel reduction treatments. Forest Ecology and Management 211(1-2): 83-96. Agne, M.C., Fontaine, J.B., Enright, N.J., Bisbing, S.M., and Harvey, B.J. 2022. 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Life history attributes of plants and the fire cycle: Proceedings of the Symposium on the Environmental Consequences of Fire and Fuel Management in Mediterranean Ecosystems, August 1-5, 1977, Palo Alto, California, USA. 451 p. Zedler, P.H. 1995. Fire frequency in southern California shrublands: biological effects and management options. Brushfires in California wildlands: ecology and resource management. International Association of Wildland Fire, Fairfield, Washington, USA: 101-112. Tables Table 1. Characteristics of study sites including name, national forest, size, elevation, fire history, and sampling dates. Site name National forest Population size (ha) Elevation (m) Fire name (year) Sampling dates (years postfire) Seiad Klamath 3198 900–1150 Miller Complex (2017) 1 Independence Klamath 3 1460 Titus (2006) 1 Mud Lake Plumas 64 1950-–2100 Moonlight (2007) 1, 2, 3, 5, 7,9 Lassen Lassen 607 1370–1500 Eiler (2014) 1, 2, 4, 9 Table 2. Mean overstory canopy closure and shrub cover for each combination of treatment types in planting experiment. Factor Combination Overstory Canopy Closure (%) Shrub Cover (%) Open/Shrubs 18 74 Open/No Shrubs 13 0.5 Shade/Shrubs 46 36 Shade/No Shrubs 90 0.5 Table 3. Mean prefire tree age, plus or minus standard error (±SE), and canopy seed storage (number of viable seeds per plot (±SE) at our study sites. Site name Mean tree age (year) ± SE Viable seeds plot -1 ± SE Seiad 68 ± 5 91800 ± 39544 Independence 60 ± 9 144059 ± 90171 Mud Lake 135 ± 5 52602 ± 17378 Lassen 56 ± 6 350609 ± 82247 Table 4. Summary of best fit generalized linear mixed models that describe the relationships between seedling height and survival, and environmental variables in the final postfire sampling interval (9 years at Lassen, 10 years at Mud Lake). Fixed effect Parameter estimate F df P R m 2 (R c 2 ) Seedling height (millimeters) 0.28 (0.32) Canopy Closure -6.15 6.51 1,22 0.02 Shrub Cover -2.64 4.09 1,23 0.05 Seedling survival (percentage) 0.5 (0.5) Canopy Closure -0.88 9.70 1,22 <0.01 Shrub Cover 0.49 8.65 ,22 <0.01 Rock Cover 1.67 9.28 ,22 <0.01 Additional Declarations No competing interests reported. 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Bovee","email":"","orcid":"","institution":"USDA Forest Service","correspondingAuthor":false,"prefix":"","firstName":"Kirsten","middleName":"M.","lastName":"Bovee","suffix":""}],"badges":[],"createdAt":"2025-08-15 23:53:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7384282/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7384282/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s42408-026-00489-1","type":"published","date":"2026-04-28T15:57:55+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90866615,"identity":"f1f76225-1a85-4a2e-81d3-d2c53811864c","added_by":"auto","created_at":"2025-09-09 07:25:19","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":4171723,"visible":true,"origin":"","legend":"\u003cp\u003eGeneral locations of Baker cypress populations, including our 4 study sites, in northern California and southern Oregon.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/b2fed1ad2e6d3411523faaac.jpg"},{"id":90866609,"identity":"1a9d2709-8a0e-47aa-81a2-328816b2be36","added_by":"auto","created_at":"2025-09-09 07:25:19","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":95893,"visible":true,"origin":"","legend":"\u003cp\u003ePredicted values of Baker cypress seedling density as a function of maximum char height and maximum scorch height based on general linear mixed models with plots nested within site as random effects. Lines and shading indicate predicted means and 95% credible intervals.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/a563c5fd0db479ef5867d601.jpg"},{"id":90868619,"identity":"0ab54daf-241a-49c8-af55-4ce364bd6692","added_by":"auto","created_at":"2025-09-09 07:49:19","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":404050,"visible":true,"origin":"","legend":"\u003cp\u003eMain effect of fire severity on a) seedling density, b) seedling survival, c) seedling health, and d) seedling height in the final year of sampling. Error bar represents standard error around the estimated marginal mean.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/7de2d46b11083c7fbfbe2cf1.jpg"},{"id":90866612,"identity":"d2391912-34e3-4993-b743-ac71552fbb29","added_by":"auto","created_at":"2025-09-09 07:25:19","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":494518,"visible":true,"origin":"","legend":"\u003cp\u003eVisualization of the main effects of time since fire and fire severity on the environmental response variables a) percent canopy closure, b) percent shrub cover, and c) percent rock cover. Data points (points), predicted values (lines) and associated confidence interval at α = 0.05 (shaded bars) are displayed.\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/8a202ecf2eae05de51936469.jpg"},{"id":90867046,"identity":"1f6da58b-416a-4bd2-ba0d-b2f82a91da05","added_by":"auto","created_at":"2025-09-09 07:33:19","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":487087,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot of Baker cypress seedling height (mm) as a result of canopy closure treatment (open vs. shaded) and year.\u003c/p\u003e","description":"","filename":"Figure5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/4a8156606d710c5d3dbbb929.jpg"},{"id":90866618,"identity":"7832a1ef-b7c8-4df3-b4c2-9e8f389cb5d4","added_by":"auto","created_at":"2025-09-09 07:25:19","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":470948,"visible":true,"origin":"","legend":"\u003cp\u003eBox plot of health status of Baker cypress seedlings, where 0 = dead and 4 = very healthy, as a function of shrub cover treatment (high vs. low) in our experimental study.\u003c/p\u003e","description":"","filename":"Figure6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/1b0c957d5ca46501b6e3318f.jpg"},{"id":108437802,"identity":"8b593506-05d8-4179-80fc-5128ec1d6ad5","added_by":"auto","created_at":"2026-05-04 16:03:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":6022444,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7384282/v1/c112eb03-b9f5-4f37-b586-9ff633cc3c16.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eComplex Effects of High Severity Fire on a Serotinous Conifer\u003c/p\u003e","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eSpecies in fire adapted ecosystems possess traits that allow them to persist and benefit from specific fire regimes (Keeley and Pausas 2022, Lamont 2022). These fire regimes are often broadly characterized in terms of severity and frequency (Tolk et al. 2023). For vegetation types associated with frequent, low severity fire regimes, studying the relationship between species traits and fire effects is relatively straightforward because fires occur often and most species survive, allowing for frequent and detailed observations of species responses to fire (Agee 1993, Van Wagtendonk 2018). However, in vegetation types associated with high severity fire regimes, direct evidence of fire effects is often lacking because fires occur very infrequently, most individuals are killed by fires, and postfire environments are often dramatically altered (Van Wagtendonk 2018). As a result, the response of vegetation to infrequent, high severity fire regimes is often inferred from indirect evidence, such as the age of cohorts or species traits (Pausas et al. 2004, Pausas et al. 2017). Although high severity fire effects can be inferred from even-aged cohorts, \u0026nbsp;metrics such as crown scorch or bole char height that can inform a more nuanced understanding of high severity fire effects are often only apparent for short periods after fires. Similarly, fire severity metrics that assess ground cover variables are often difficult to discern after extended periods of time. Although we may know that species are associated with high severity fire regimes, without immediate postfire observations, we may not fully understand how fire behavior affects species and postfire environmental conditions over both short and long time frames\u0026nbsp;(Tada et al. 2024).\u003c/p\u003e\n\u003cp\u003eBaker cypress (\u003cem\u003eHesperocyparis bakeri\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/em\u003e(Jeps.) Bartel)\u003cem\u003e\u0026nbsp;\u003c/em\u003eis a serotinous conifer associated with high severity fire regimes (Barbour 2007, Vogl et al. 1977). Baker cypress occurs in 11 widely scattered locations across northern California and southern Oregon. It is the northernmost naturally occurring cypress in the world, found at elevations of up to 2100 m where it grows among high-elevation conifers such as red fir (\u003cem\u003eAbies magnifica\u003c/em\u003e A. Murray bis) and western white pine (\u003cem\u003ePinus monticola\u003c/em\u003e Douglas ex D. Don). Baker cypress has closed cones, considered an adaptation to high intensity fires because heat is necessary to open cones and release seeds (Barbour 2007, Lamont 2022, Pausas et al. 2004). Baker cypress possess other traits associated with high severity fire, including retaining numerous dead lower branches, growing in dense stands, and having thin, papery bark that is highly flammable\u0026nbsp;(Pausas et al. 2017, Schwilk and Ackerly 2001). Baker cypress generally occur in even aged cohorts, indicating that the parent generation experienced complete mortality after a high severity fire. Baker cypress is thought to require high severity fire in order to create favorable postfire conditions for germination and seedling survival such as high light availability and exposed bare mineral soil (Keeley and Zedler 1998, Lamont et al. 1991, Vogl et al. 1977). Most species of cypress are poor competitors and postfire recruitment may require high severity fire to reduce competition by killing the dormant seeds of other species (Keeley and Zedler 1998, Shi et al. 2022). Until recently, observations of wildfire effects to Baker cypress populations were rare. There was little direct evidence of\u0026nbsp;fire effects on cone opening and germination immediately after fires or information about how environmental characteristics affected by fires influence population dynamics over longer time frames.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnderstanding how fire affects Baker cypress populations has become more urgent as natural fire regimes have become fundamentally altered over the past century. Baker cypress is sensitive to fire return interval because the primary seed source for postfire regeneration comes from seeds accumulated inside cones and the time between fires determines the size of this canopy seed bank (Bliss and Zedler 1997, Keeley et al. 1999, Lamont and Enright 2000, Pausas et al. 2004). Until recently, the primary threat to Baker cypress was fire suppression. A 2006 status survey of Baker cypress found that fire had been excluded from six of the 11 known populations for 100 years or longer (Rentz and Merriam 2009). Mature adult cypress in several populations were dying as a result of interspecific competition in areas that had experienced prolonged fire exclusion, with no evidence of regeneration (Keeler-Wolf 2004). If fire return intervals exceed the lifespan of the trees or the longevity of the seeds stored in the canopy, cypress and other closed cone conifers can die before they reproduce (Keeley et al. 1999, Keeley and Fotheringham 2000, Lamont 1991,Zedler 1995).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA more recent and emerging threat to Baker cypress is too frequent fire. The extent and frequency of wildfires has increased dramatically across the western US (Iglesias et al. 2022, Juang et al. 2022, Westerling 2016) and seven of the 11 Baker cypress populations have burned in wildfires over the past 20 years. Baker cypress do not begin producing ovulate cones until the trees are at least 14 years of age or older, and these cones require two years to mature (Armstrong 1980). In addition, seed viability and germination rates among California cypress can be quite low, extending the amount of time required for populations to store enough seed to replace the parent population (Zedler 1977). Minimum fire return intervals in vegetation dominated by California cypress is estimated to be 30 years, while mean fire return intervals are estimated at 55 years (Van de Water and Safford 2011). Climate change and associated stressors may be lengthening the amount of time needed for populations to achieve sufficient canopy seed storage as warmer, drier conditions may reduce the cone production rates of stressed trees and result in higher mortality rates (Enright et al. 2015).\u0026nbsp;One Baker cypress population was almost completely extirpated by successive fires that burned before seedlings could produce cones, and six of the remaining ten Baker cypress populations are now completely or partially comprised of immature seedlings. These populations are at risk of extirpation if they burn again before these trees can produce cones (Agne et al. 2022, Brennan and Keeley 2019, de Gouvenain and Ansary 2006, Keeley et al. 1999, Lamont and Enright 2000, Ne\u0026apos;eman et al. 1999, Rodr\u0026iacute;guez‐Buritic\u0026aacute; and Suding 2013, Wuenschel et al. 2023, Zedler 1977).\u003c/p\u003e\n\u003cp\u003eAlthough the recent dramatic increase in the number and frequency of fires pose a significant threat to Baker cypress, it also provides a unique opportunity to evaluate in more detail how fire affects populations both in the short term, through direct effects on germination, and over longer time frames by influencing environmental variables associated with survival, growth, and health. Determining what factors promote Baker cypress germination, survival, growth, and health is critical for developing management recommendations and conservation strategies that will ensure the persistence of this and other closed cone conifer species in an era of altered fire regimes and changing climates (Agne et al. 2022).\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eStudy Objectives\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eWe sampled four Baker cypress populations that burned in wildfires\u0026nbsp;between 2006 and 2017 to evaluate postfire germination. We continued data collection at two sites and established a third experimental site to identify factors that contribute to the survival, growth, and health of Baker cypress seedlings over time. Our study was designed to answer the following questions:\u003c/p\u003e\n\u003col\u003e\n \u003cli\u003eWhat factors promote postfire regeneration of Baker cypress?\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eHow did fire severity influence longer-term survival and growth of Baker cypress seedlings over time?\u003c/li\u003e\n \u003cli\u003eWhat environmental factors influence longer-term density, survival, growth, and health of Baker cypress seedlings, and how were these variables affected by fire severity?\u0026nbsp;\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"METHODS","content":"\u003cp\u003eBaker cypress occurs in 11 widely scattered locations across the northern Sierra Nevada, Cascade, and Siskiyou Mountains\u0026nbsp;(Figure 1). The Siskiyou occurrences are found on serpentine and granitic soils, while in the Sierra Nevada and Cascade ranges Baker cypress is found on volcanic substrates. Baker cypress occurs at elevations from 1157 to 2146 feet on north to northeast facing slopes and is associated with chaparral, mixed evergreen and montane coniferous forest vegetation types (Wolf 1948). Baker cypress can grow over 30 m tall with trunks of up to 1.5 m in diameter. Baker cypress is found primarily on public lands managed by the USDA Forest Service and the USDI Bureau of Land Management. For this study, we focused on populations distributed broadly across the species range that burned in wildfires between 2006 and 2017, including: 1)\u0026nbsp;the Independence site (Siskiyou) that burned in the 2006 Titus Fire; 2) the Mud Lake site (Sierra Nevada) that burned during the 2007 Moonlight Fire; 3) the Lassen site (Cascades) that burned during the 2014 Eiler Fire; and 4) the Seiad site (Siskiyou) \u0026nbsp;that burned during the 2017 Miller Complex Fire (Table 1).\u003c/p\u003e\n\u003ch2\u003ePrefire stand conditions\u003c/h2\u003e\n\u003cp\u003ePrefire stand conditions were assessed as part of a range-wide survey of Baker cypress conducted in 2006 (Rentz and Merriam 2009). Between three and 15 809.4 m\u003csup\u003e2\u003c/sup\u003e circular plots were randomly established at each location depending on accessibility, size, and distribution of the Baker cypress stand. Within each plot we recorded species, diameter at breast height (dbh), height, and status (live vs. dead) for all trees (dbh \u0026gt;10.16 cm) and saplings (dbh \u0026lt; 10.16 cm and height \u0026gt; 1.37 meter).\u003c/p\u003e\n\u003cp\u003eWe measured seedling density using eight 1 m\u003csup\u003e2\u003c/sup\u003e quadrat frames placed systematically along transects radiating in the four cardinal directions from plot center. Within each 1 m\u003csup\u003e2\u003c/sup\u003e quadrat we recorded the number and species of all tree seedlings (height \u0026lt; 1.37 m) as well as the percent cover of shrubs, herbs and ground cover variables including litter, rock, and bare ground. Litter depth was measured at each 1-m\u003csup\u003e2\u003c/sup\u003e quadrat and a spherical densiometer was used to measure overstory canopy closure.\u003c/p\u003e\n\u003cp\u003eTo determine tree age, we collected core samples from six Baker cypress individuals representing the entire range of size classes present. Cores were collected at the lowest possible location along the bole using an increment borer. To calculate canopy seed storage, we estimated the number of cones on each Baker cypress tree and the percentage of closed cones. We then collected ten cones each from the same six trees sampled to determine tree age. We counted the number of fully developed and underdeveloped seeds present in each cone and tested a sample of 20 fully developed seeds by exposing them to a tetrazolium staining agent (Peters 2000). The number of viable seeds per tree was then calculated based on the following formula:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNumber of viable seeds/tree (canopy seed storage/tree) = # of seeds/cone \u003cstrong\u003ex\u0026nbsp;\u003c/strong\u003e% viability \u003cstrong\u003ex\u0026nbsp;\u003c/strong\u003e# of cones/tree \u003cstrong\u003ex\u0026nbsp;\u003c/strong\u003e% closed cones/tree\u003c/p\u003e\n\u003cp\u003ePlot level estimates of canopy seed storage were then made by multiplying the average number of viable seeds tree\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003eby the number of trees in each plot.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePostfire germination\u003c/h2\u003e\n\u003cp\u003eTo understand factors that influenced the immediate (i.e., first growing season) postfire germination of Baker cypress, we repeated the prefire sampling methods at our four study sites. In addition to prefire stand condition data, we recorded postfire indicators of severity, including scorch height, bole char height, percent crown scorch andtorch,\u0026nbsp;and mortality of all trees within the larger plot. We also estimated overall fire severity at the 1 m\u003csup\u003e2\u003c/sup\u003e quadrat scale using a categorical system that includes both soil and vegetation factors developed by the US Department of the Interior (2003).\u0026nbsp;Low severity plots were characterized by scorched to lightly burned vegetation and substrates, while high severity plots were characterized by moderately to heavily burned vegetation and substrates. We chose this categorical metric because it includes a broad suite of variables associated with fire severity that can be readily determined in the field and is easily interpreted by managers.\u003c/p\u003e\n\u003ch2\u003ePostfire seedling survival, growth and health\u003c/h2\u003e\n\u003cp\u003eTo evaluate longer-term postfire seedling survival, growth, and health we continued our data collection efforts for nine years at the Lassen study site, and ten years at the Mud Lake study site (Table 2). We repeated measures of data collected at the 1 m\u003csup\u003e2\u003c/sup\u003e quadrat scale (vegetation cover, ground cover, tree seedling species and number, duff and litter depth, and overstory canopy closure).\u0026nbsp;Within each quadrat, we randomly selected five Baker cypress seedlings, and for each measured its height and evaluated its health status on a categorical scale of zero to four (0 = dead, 1 = no new growth, 2 = less than 5 cm new growth and some dying parts, 3 = more than 5 cm of new growth and some dying parts, 4 = more than 5 cm of growth and no dying parts).\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePlanting experiment\u0026nbsp;\u003c/h2\u003e\n\u003cp\u003eWe conducted an additional experiment to specifically investigate the effects of shrub cover and overstory canopy closure on Baker cypress seedling survival, growth, and health. In 2008, we planted 58 one-year old nursery grown seedlings in 16 1 m\u003csup\u003e2\u003c/sup\u003e plots adjacent to the Mud Lake site in areas that had burned during the 2007 Moonlight Fire. Seedlings were planted where levels of shrub cover and overstory canopy closure naturally differed (Table 2). We established four replicates for each combination of shrub cover and canopy closure. Data was collected as described for the postfire seedling survival, growth, and health sampling above, including seedling height and health status, vegetation and ground cover, litter depth, and overstory canopy closure.\u0026nbsp;Plots were resampled in 2009, 2010, 2012 and 2015.\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003eStatistical Analyses\u003c/h2\u003e\n\u003cp\u003eGeneralized linear mixed models were used to identify factors that influenced postfire germination rates as well as longer-term trends in seedling growth, health, and survival over time. Our evaluation of longer-term trends focused on differences between high and low severity fire effects A random effects term defined for each nested plot and site combination was included in all models to account for potential differences in response variables due to site identity and to the repeated measures of plots in some analyses. Full models that included all predictor variables were fit using maximum likelihood with the lme4 package in R version 4.3.1 (Bolker et al. 2009, Bates et al. 2015, R Core Team 2025). We then performed backward elimination of non-significant effects with the LmerTest package (Kuznetsova et al. 2017). The relative contributions of fixed and random effects were estimated by calculating marginal and conditional pseudo-R values for each model (Nakagawa and Schielzeth 2013) with the MuMin package (Barton and Barton 2015).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo test for the effects of canopy closure and shrub cover in our planting experiment on Baker cypress seedling growth, health, and survival we used repeated measures ANOVA (Girden 1992) with the rstatix package in R version 4.3.1(Kassambara 2023, R Core Team 2025) with time (year) specified as the within-subjects factor. Significant interactions between factors were evaluated using pairwise paired t-tests\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003ebetween the levels of the within-subjects factor and \u003cem\u003eP\u003c/em\u003e values were adjusted using the Bonferroni multiple testing correction method.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003ch2\u003ePrefire stand conditions and postfire germination\u003c/h2\u003e\n\u003cp\u003eMean prefire stand ages at our study sites ranged from 56 to 135 years (Table 3). Canopy seed storage was high, ranging from over 350,000 viable seeds plot\u003csup\u003e-1\u003c/sup\u003e at Lassen to just over 50,000 viable seeds plot\u003csup\u003e-1\u003c/sup\u003e at Mud Lake (Table 3). Mean postfire germination in our study plots was also high, averaging 6.3 seedlings m\u003csup\u003e-2\u003c/sup\u003e (\u003cu\u003e+\u003c/u\u003e 1.2) or 63,173 (\u003cu\u003e+\u003c/u\u003e 1200) seedlings ha\u003csup\u003e-2\u003c/sup\u003e. First-year seedling density, averaging 870 (\u003cu\u003e+\u003c/u\u003e 451) seedlings per parent tree ,was well above that necessary to replace the parent population at all of our study sites.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eScorch height and char bole height were the most significant predictors of Baker cypress germination rates and together explained 45% of the variation in first-year seedling density (Figure 2). Seedling density one year postfire was positively influenced by the maximum height of scorch (F\u003csub\u003e1,29\u003c/sub\u003e = 24.8, \u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u0026lt; 0.001). For every 1 m increase in scorch height, an additional 1.9 seedlings m\u003csup\u003e-2\u003c/sup\u003e germinated. On the other hand, maximum char height negatively influenced germination (F\u003csub\u003e1,29\u003c/sub\u003e = 18.7, \u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u0026lt; 0.001), for every 1 m of char height, seedling density declined by 1.4 seedlings m\u003csup\u003e-2\u003c/sup\u003e. Other variables, including ground cover characteristics and prefire canopy seed storage, were not related to postfire germination rates.\u003c/p\u003e\n\u003ch2\u003eLong-term seedling survival, growth, and health\u003c/h2\u003e\n\u003cp\u003eFire severity was a significant predictor of seedling density, survival, and health, but not of seedling height in the final year of sampling (nine years postfire at the Mud Lake site and ten years postfire at the \u0026nbsp;Lassen site; Figure 3). Fire severity explained 22% of the variation in seedling densities among plots in the final year of sampling (F\u003csub\u003e1,25\u003c/sub\u003e = 7.47, \u003cem\u003eP\u003c/em\u003e = 0.01, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.22, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.22 ). High severity plots had an estimated mean density of 7.3 seedlings m\u003csup\u003e-2\u003c/sup\u003e, which was more than triple the estimated density of 2.2 seedlings m\u003csup\u003e-2\u0026nbsp;\u003c/sup\u003ein low severity plots. Long-term survival of first year germinants was estimated to be twice as high in high severity plots (76%) versus low severity plots (38%) at the final year of sampling (F\u003csub\u003e1,23\u003c/sub\u003e = 9.83, \u003cem\u003eP\u003c/em\u003e = 0.004, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.27, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.32). Seedling health also varied by fire severity, with higher estimated health scores of 3.7 in high severity plots and 3.2 in low severity plots (F\u003csub\u003e1,24\u003c/sub\u003e = 6.69, \u003cem\u003eP\u003c/em\u003e = 0.02, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.21, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.21). These health scores indicated a condition that is intermediate between health class 3 (healthy) and Health Category 4 (very healthy). Estimated seedling height, by contrast, was not significantly different between high and low severity plots in the final year of sampling (F\u003csub\u003e1,23\u003c/sub\u003e = 0.36, \u003cem\u003eP\u003c/em\u003e = 0.55, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.01, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.07).\u003c/p\u003e\n\u003ch3\u003e\u003cem\u003eEnvironmental predictors of seedling survival and growth\u0026nbsp;\u003c/em\u003e\u003c/h3\u003e\n\u003cp\u003eCanopy closure and ground cover variables were not significant predictors of seedling density or health. However, canopy closure, shrub cover, and rock cover were found to be significant predictors of seedling height and survival (Table 4). Coarse woody debris, bare ground cover, herbaceous cover, moss cover, and litter and duff depth did not contribute to best-fit models for any of the seedling attributes. In the final year of sampling (10 years postfire at Mud Lake, 9 years postfire at Lassen), average seedling height was negatively associated with both canopy closure (F\u003csub\u003e1,22\u003c/sub\u003e = 6.51, \u003cem\u003eP\u003c/em\u003e = 0.02), and with shrub cover (F\u003csub\u003e1,23\u003c/sub\u003e = 4.09, \u003cem\u003eP\u003c/em\u003e = 0.05). Twenty-eight percent of the variation in seedling height was explained by these environmental factors. Seedling height was predicted to be 6 cm shorter for every 10% increase in canopy closure, and 1 cm shorter for every 10% increase in shrub cover. The percentage of first-year germinants surviving to the final year of sampling was negatively associated with canopy closure (F\u003csub\u003e1,22\u003c/sub\u003e = 9.70, \u003cem\u003eP\u003c/em\u003e \u0026lt;0.01), but positively associated with both shrub cover (F\u003csub\u003e1,22\u003c/sub\u003e = 8.65, \u003cem\u003eP\u003c/em\u003e \u0026lt;0.01) and with rock cover (F\u003csub\u003e1,22\u003c/sub\u003e = 9.28, \u003cem\u003eP\u003c/em\u003e \u0026lt;0.01). A 10% increase in canopy closure predicted a 9% decrease in survival, while a 10% increase in shrub cover predicted a 5% increase in survival. A 10% increase in rock cover predicted a 17% increase in survival.\u0026nbsp;\u003c/p\u003e\n\u003ch3\u003e\u003cem\u003eFire effects to the growing environment\u0026nbsp;\u003c/em\u003e\u003c/h3\u003e\n\u003cp\u003eThe growing environment for Baker cypress seedlings at the Lassen and Mud Lake study sites was dynamic, varying with both time since fire and fire severity (Figure 4). Canopy closure was on average 39% higher in lower severity plots (F\u003csub\u003e1,74\u003c/sub\u003e = 4.36, \u003cem\u003eP\u003c/em\u003e = 0.04) but decreased over time in both high and low severity plots (F\u003csub\u003e1,90\u003c/sub\u003e = 75.84, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.0001). Time since fire and fire severity explained 30% of the variation in canopy closure among plots, while the effect of site and plot explained an additional 41% of this variation (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.30, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.71). Shrub cover increased over time in both high and low severity plots, however this increase occurred at a significantly greater rate in high severity plots (F\u003csub\u003e1,105\u003c/sub\u003e = 5.01, \u003cem\u003eP\u003c/em\u003e = 0.03). Rock cover was on average three times higher in high severity plots (F\u003csub\u003e1,51\u003c/sub\u003e = 8.24, \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.01) and decreased over time in both high and low severity plots (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.16, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.47). Together, time since fire and fire severity explained 22% of the variation in shrub cover between plots (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.22, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.65) and 16% of the variation in rock cover between plots (R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003em\u003c/sub\u003e = 0.16, R\u003csup\u003e2\u003c/sup\u003e\u003csub\u003ec\u0026nbsp;\u003c/sub\u003e= 0.47).\u0026nbsp;\u003c/p\u003e\n\u003ch2\u003ePlanting experiment\u003c/h2\u003e\n\u003cp\u003eIn our planting experiment that evaluated the effects of shrub cover and overstory canopy closure on the growth, health, and survival of planted Baker cypress seedlings, we observed a significant interaction effect between years since planting and seedling height (F\u003csub\u003e3,56\u003c/sub\u003e = 7.4, \u003cem\u003eP\u003c/em\u003e = 0.0003). All seedlings were taller three and five years after planting, but significantly higher where canopy closure was low (Figure 5). The health status of seedlings was not associated with year or canopy closure, but was significantly higher when seedlings were grown in association with shrubs (F\u003csub\u003e1,62\u003c/sub\u003e = 11, \u003cem\u003eP\u003c/em\u003e = 0.002, Figure 6). Mortality rates increased significantly from less than 1% in the first two years after to planting, to over 25% mortality after 7 years (F\u003csub\u003e3,45\u003c/sub\u003e = 10, \u003cem\u003eP\u003c/em\u003e = 0.0004). However, mortality was not associated with shrub cover or overstory canopy closure in our planting experiment.\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\u003ch2\u003ePostfire germination\u003c/h2\u003e\u003cp\u003eWe found that fire severity was the most important driver of Baker cypress germination. However, the relationship between fire severity and germination was more complex than we predicted and included both positive and negative effects. Scorch height was positively related to postfire germination, likely because heat is required to open serotinous cones and release seeds stored in the canopy (Enright and Lamont \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1989\u003c/span\u003e, Habrouk et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Vogl et al. \u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e1977\u003c/span\u003e). Milich et al. (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) found that Baker cypress cones opened when heated to 500\u0026deg;C. Higher scorch heights indicate fire effects that extend into the canopy and result in scorching of needles without reaching temperatures or durations of heating that result in needle defoliation (Alexander and Cruz \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Ryan and Noste \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e1985\u003c/span\u003e, Ryan \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2002\u003c/span\u003e, Turner et al. \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e1994\u003c/span\u003e)..\u003c/p\u003e\u003cp\u003eConversely, we found that seedling densities declined as tree bole char height increased. Charring of the tree bole can indicate higher fire intensity and longer duration of exposure than scorch (Alexander and Cruz \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Ryan and Noste \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e1985\u003c/span\u003e, Ryan \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2002\u003c/span\u003e, Turner et al. \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e1994\u003c/span\u003e,). Although cypress require relatively high temperatures for cone opening (i.e., 500\u0026deg;C), Milich et al. (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) found that Baker cypress seed viability was negatively affected by longer heating durations and no germination was observed in seeds exposed to heat for more than two minutes, regardless of temperature. This suggests that Baker cypress may be adapted to faster moving crown fires, which would allow cones stored in the tree canopy to be heated to sufficient temperatures to open and release seeds, without being exposed to these temperatures for extended periods. Brennan and Keeley (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) found lower germination rates of Tecate cypress (\u003cem\u003eHesperocyparis forbesii\u003c/em\u003e (Jeps.) Bartel) in areas where fire severity was high, and studies of other serotinous species have also found that longer durations of heating reduced seed survival (Alexander and Cruz \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Habrouk et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1999\u003c/span\u003e,Tada et al. \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Extensive charring of the tree bole may be a result of fire suppression, where an accumulation of surface fuels can result in higher fire intensity and longer residence times (Agee and Skinner \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, Alexander and Cruz \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2012\u003c/span\u003e, Brodie et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2024\u003c/span\u003e, Keane \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). None of our four study sites had previously burned in recorded history, and all were heavily encroached by other species of conifer.\u003c/p\u003e\u003cp\u003ePrevious authors have suggested that cypress require high severity fire not only to open serotinous cones, but also to prepare a receptive seed bed of bare mineral soil conducive for germination (Barbour \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, Vogl et al. \u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e1977\u003c/span\u003e). However, we found that ground cover variables were not significant predictors of postfire germination rates at our study sites. Instead, the effects of fire severity on tree-level variables related to cone opening and seed dispersal were more important than fire-related changes to ground cover. This suggests that seed availability, mediated by fire intensity, was the primary driver of postfire germination in our Baker cypress populations.\u003c/p\u003e\u003cp\u003eIt was surprising that prefire canopy seed storage was not a significant predictor of postfire germination at our study sites. However, the mean age of the Baker cypress we evaluated was between 56 and 135 years, giving these populations sufficient time to accumulate cones and develop robust canopy seed banks. The mean number of viable seeds available in the canopy of trees in our study plots was almost 200,000, suggesting that seed availability was not a limiting factor. However, fires that occursin younger stands, that have not had time to develop a sufficient canopy seed bank, pose a serious threat to all cypress species in California (Agne et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Brennan and Keeley \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, de Gouvenain and Ansary \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2006\u003c/span\u003e,, Keeley et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Ne'eman et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Wuenschel et al. \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Zedler \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e1977\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\u003ch2\u003eLong-term seedling survival, growth, and health\u003c/h2\u003e\u003cp\u003eWe found that fire severity not only determined germination rates, but also had longer-term implications for Baker cypress seedling survival, growth, and health. Seedling density, survival, and health were all higher after nine or ten years in plots that burned at high severity, while seedling height did not differ between high and low severity plots. It is likely that these longer-term effects resulted from fire effects to the postfire growing environment for seedlings, including the negative effects of canopy closure in low severity plots, and the positive effects of nurse objects such as rocks and shrubs that were promoted by high severity fire. These effects are consistent with studies of post-fire recruitment for other conifer species. Owen et al. (\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) also found that high severity fire promoted environmental conditions, including understory plant and coarse wood cover, that benefitted ponderosa pine (\u003cem\u003ePinus ponderosa\u003c/em\u003e Douglas ex Lawson \u0026amp; C. Lawson) seedling growth 11\u0026ndash;16 years after the fire.\u003c/p\u003e\u003cp\u003eSimilar to the patterns we observed in postfire germination, many ground cover variables were not associated with seedling survival, growth, or health at our study sites. This suggests that where canopy seed storage is sufficient to promote germination, established cypress seedlings are not strongly influenced by other herbaceous species or by ground cover variables such as litter.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\u003ch2\u003eCanopy closure\u003c/h2\u003e\u003cp\u003eAreas that burned at high severity were characterized by lower canopy closure, which was negatively associated with seedling growth and survival. More trees were killed by high severity fire effects that reduced or eliminated overstory shade from tree crowns, increasing light availability to cypress seedlings. Observations of mature trees have indicated that Baker cypress is a poor competitor and experiences significant mortality when overtopped by other species; our study indicates that seedlings similarly require high light environments (Keeler-Wolf \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2004\u003c/span\u003e). Mallek (\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) found that McNab cypress (\u003cem\u003eHesperocyparis macnabiana\u003c/em\u003e (A. Murray bis) Bartel) seedlings experience complete mortality under closed canopy conditions. Many species associated with high severity fire regimes thrive in open conditions (Bond et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2012\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eThe high amounts of overstory shade at our study sites may be a result of fire suppression, as these populations of Baker cypress had become heavily encroached by other conifer species prior to burning. For example, the Mud Lake site had total tree densities of 563 (+- 40) trees acre\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and only 17% of the trees present were Baker cypress. Similarly, Baker cypress represented only 55, 47, at 49% of stand densities at the Seiad, Independence and Lassen study sites, respectively. The high stand densities resulting from fire suppression and conifer encroachment contributed to increased overstory canopy from snags after fires that negatively affected Baker cypress seedlings. High snag densities also contribute to increased fuel loads that put immature populations at increased risk of fires occurring before the new cohort produces cones (Coppoletta et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\u003ch2\u003eShrub cover\u003c/h2\u003e\u003cp\u003eWe found that shrub cover promoted seedling health in our planting experiment and long-term seedling survival in our natural populations. Shrubs can promote the establishment, survival and growth of tree species, particularly in arid environments (Legras et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2010\u003c/span\u003e, G\u0026oacute;mez-Aparicio et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Bustamante-S\u0026aacute;nchez et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2011\u003c/span\u003e, Rolo et al. \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, van Zonneveld et al. \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). Shrubs can provide shade that reduces reduce solar radiation and moderate microclimate extremes, leading to a reduction of water stress and evapotranspirative demand (Davis et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Crockett and Hurteau \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Gray and Spies \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1997\u003c/span\u003e, Gray et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, Holmgren et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e1997\u003c/span\u003e). In the southwestern United States, Crockett and Hurteau (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) concluded that postfire planting might be delayed until shrubs have established because they can increase postfire planting success. Shrubs also play an important role in promoting soil nutrients and providing protection from herbivory, trampling, and other disturbances (G\u0026oacute;mez‐Aparicio et al. 2005, Legras et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2010\u003c/span\u003e, Loayza et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). As annual snowpacks decline as a result of climate change, shrubs may also provide thermal protection from frost (Inouye \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). This protection might increase the survival of Baker cypress, a species found at the highest elevation and most northern sites of any cypress species in California, where populations are exposed to extreme cold.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\u003ch2\u003eRock cover\u003c/h2\u003e\u003cp\u003eWe found that that rock cover, higher in plots that burned at high severity, promoted Baker cypress seedling survival. High severity fire is effective at removing vegetation as well as duff and litter layers that can obscure rocks in long unburned landscapes. Rocks can create sheltered microsites that benefit seedlings by decreasing soil and air temperatures, increasing soil moisture, and protecting seedlings from other stressors such as herbivory and trampling (Shemesh \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Rock cover can also limit the space available for competitor species (Alvarez-Yepiz et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Although some studies have found that facilitation by nurse plants can provide more benefits to seedlings than rocks because they increase soil nutrient availability (Loayza et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), we found that rocks had a greater positive effect on seedling survival than shrubs and seedlings had slower growth rates in plots with higher shrub cover. Other studies have found that rocks can be more effective nurse objects than shrubs or other plant species because they do not limit light availability or compete with seedlings for soil resources (Mlambo and Chiparange \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\u003ch2\u003eDrought\u003c/h2\u003e\u003cp\u003eThe apparent facilitative effect of shrubs and rocks on Baker cypress seedlings may be surprising given that our study populations do not occur in extremely arid environments where these types of effects are frequently observed (e.g., (G\u0026oacute;mez-Aparicio et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2004\u003c/span\u003e, Shemesh \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). However, other California and Arizona cypress populations have demonstrated sensitivity to drought, (Goforth \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, Verrier \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Wuenschel et al. \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) and our study focused on postfire environments that are generally characterized by open, dry conditions often associated with postfire regeneration failure (Davis, et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, Dobrowski et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, Rodman et al. \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). For serotinous conifers where seed availability is not limited, high severity fires may create conditions that are beneficial for seedlings by increasing the abundance of nurse objects such as rocks, coarse wood, and shrubs (Kuenzi et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, Owen et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2020\u003c/span\u003e, Shive et al. \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\u003ch2\u003eSurvival\u003c/h2\u003e\u003cp\u003eOne of the strongest effects of fire severity we observed was on seedling survival. Even ten years after fire, 76% of seedlings that germinated in areas that burned at high severity survived, while only 38% of seedlings were still alive in areas that burned at low severity. High seedling survival rates contribute to higher densities of adult trees, which can benefit cypress populations by promoting high severity fire effects (Pausas et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), as well as by increasing stand level canopy seed storage that is critical for postfire regeneration (Harvey and Holzman \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2014\u003c/span\u003e, Moya et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, Turner et al. \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, Verkaik and Espelta \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Higher density stands may also increase the rate at which populations reach reproductive maturity. Agne et al. (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) found that knob cone pine (\u003cem\u003ePinus attenuata\u003c/em\u003e Lemmon) in high-density stands had a\u0026thinsp;~\u0026thinsp;40% greater probability of reaching reproductive maturity than trees in low density stands at an age of ten years. Rapid development of a large canopy seed bank is a critical resilience mechanism to short-interval fires, particularly if warming and drying conditions create an opposing \u0026lsquo;interval squeeze\u0026rsquo; effect by increasing mortality rates and reducing cone production between fires (e.g., Enright et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eNine to ten years postfire our study plots still supported cypress densities that were well above that necessary to replace the parent generation, regardless of severity. In older stands of cypress where seed availability is not limiting, postfire germination rates are likely to exceed the replacement threshold as long as fire severity is sufficient to open cones and disperse seeds while not reaching lethal temperatures or durations. While the Mud Lake (135 years old) and Lassen (56 years old) populations were old enough to have amassed adequate seed storage, recruitment may be below replacement thresholds in younger stands with less canopy seed storage. A number of other studies have found that immature and young stands of cypress are significantly threatened by repeated fire (Agne et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2022\u003c/span\u003e, Brennan and Keeley \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, de Gouvenain and Ansary \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2006\u003c/span\u003e, Keeley et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Ne'eman et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e1999\u003c/span\u003e, Rodr\u0026iacute;guez-Buritic\u0026aacute; and Suding \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, Wuenschel et al. \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, Zedler \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e1977\u003c/span\u003e). In 2021, four years after the last seedling data was collected at our Mud Lake study site, a second wildfire burned through the Baker cypress population and killed over 99% of the young trees before they had produced cones.\u003c/p\u003e\u003c/div\u003e"},{"header":"CONCLUSIONS","content":"\u003cp\u003eAlthough Baker cypress has long been associated with high severity fire regimes, we found that the effects of fire severity are complex and include both positive and negative, as well as short and long-term effects. The positive effects of crown scorch coupled with the negative effects of char bole height suggest that while Baker cypress requires heat to open cones, there are limits to the temperature or duration of heat that seeds stored in the canopy can tolerate. This nuanced understanding of the effect of fire on Baker cypress would not have been possible without immediate postfire assessments of fire severity following recent wildfires.\u003c/p\u003e\u003cp\u003eFire severity effects on ground cover and overstory canopy closure were not important determinants of germination rates, perhaps because the populations we studied all had large amounts of canopy seed storage and seed availability was not limiting. However, over longer time frames, Baker cypress density, survival, health and growth were significantly impacted by fire severity and its effects on environmental variables, including overstory canopy closure, rock cover and shrub cover. Although canopy seed storage and cone opening appeared to be the main driver of Baker cypress germination rates, variables associated with increased light availability and drought stress refugia were important for the longer term density, survival, health, or height of Baker cypress seedlings. These effects were evident even nine or ten years after fires, demonstrating that fire severity has persistent long-term effects on Baker cypress populations.\u003c/p\u003e\u003cp\u003eIn an era of altered fire regimes and rapidly changing climatic conditions, optimizing fire effects to achieve sufficient crown scorch while minimizing fire behavior that causes extensive bole char may help ensure the persistence of Baker cypress populations into the future. Prescribed or managed fire in Baker cypress stands must promote crown fire effects to open cones, while avoiding sustained or persistent burning. Adverse fire effects, such as extensive bole charring, may occur where surface fuel loading is high or where pile burning occurs near Baker cypress trees. Reduction of surface fuels in mature stands may help to reduce fire intensity during wildfires, but reduction of ladder fuels or thinning of stands may have unintended negative effects if these actions lower the probability of canopy scorching. Low severity fire will likely not be effective at opening cones, whereas fire intensity that results in extensive bole charring may have lethal effects to seeds.\u003c/p\u003e\u003cp\u003eStand management following wildfire should promote long-term cypress seedling survival to ensure sufficient canopy seed storage prior to subsequent fires. Postfire salvage logging may help to reduce snag densities and provide open conditions for seedlings while also reducing fuel loads to protect immature populations from subsequent fires. When actively planting Baker cypress seedlings, either to reintroduce extirpated populations or to supplement natural regeneration, selecting open sites and using rocks and shrubs as nurse objects could promote the survival of the planted seedlings. The greatest threat to Baker cypress and other California cypress species is shortened fire return intervals, so efforts to reduce fuel loads and to effectively deploy suppression tactics around immature populations is critical to the persistence of these iconic fire adapted species into the future.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eKM developed prefire sampling design at all study sites and postfire sampling design at Seiad, Independence, and Mud Lake study sites. KM and KB collaborated on postfire monitoring design at Lassen study site and on all statistical analyses. KM wrote the majority of the manuscript and KB contributed substantially to revisions.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThis project was partially funded by the Joint Fire Science Program (Project ID Number: 06-2-1-17) with cooperation from the USDA Forest Service. We would like to thank Erin Rentz, Max Creasy, and numerous field assistants and resource specialists from the USDA Forest Service and DOI Bureau of Land Management for their help with this project\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data used to draw conclusions in this paper are currently in use by the authors and will be published in their entirety simultaneous with the final in-progress publication. Until that time, the data may be accessed upon request from the corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAgee, J. 1993. Fire ecology of Pacific Northwest forests. 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Wiley, New York: 295-358.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWesterling, A.L. 2016. Increasing western US forest wildfire activity: sensitivity to changes in the timing of spring. Phil. Trans. R. Soc. B 371(1696): 20150178.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eWuenschel, A., Bartel, J.A., and Bernal, A. 2023. Forty Years of Change in Piute Cypress (Hesperocyparis nevadensis), a Rare California Tree, After Frequent Fire and Drought. Aliso: A Journal of Systematic and Floristic Botany 41(1): 52-66.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eZedler, P.H. 1977. Life history attributes of plants and the fire cycle: Proceedings of the Symposium on the Environmental Consequences of Fire and Fuel Management in Mediterranean Ecosystems, August 1-5, 1977, Palo Alto, California, USA. 451 p.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eZedler, P.H. 1995. Fire frequency in southern California shrublands: biological effects and management options. Brushfires in California wildlands: ecology and resource management. International Association of Wildland Fire, Fairfield, Washington, USA: 101-112. \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1. Characteristics of study sites including name, national forest, size, elevation, fire history, and sampling dates.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"569\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSite name\u0026nbsp;\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\u0026nbsp;\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 72px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNational forest\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePopulation size (ha)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eElevation (m)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 114px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFire name (year)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSampling dates (years postfire)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003eSeiad\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003eKlamath\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e3198\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e900\u0026ndash;1150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eMiller Complex (2017)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003eIndependence\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003eKlamath\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e1460\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eTitus (2006)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003eMud Lake\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003ePlumas\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e1950-\u0026ndash;2100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eMoonlight (2007)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1, 2, 3, 5, 7,9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp\u003eLassen\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 72px;\"\u003e\n \u003cp\u003eLassen\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e607\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 90px;\"\u003e\n \u003cp\u003e1370\u0026ndash;1500\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 114px;\"\u003e\n \u003cp\u003eEiler (2014)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 96px;\"\u003e\n \u003cp\u003e1, 2, 4, 9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2. Mean overstory canopy closure and shrub cover for each combination of treatment types in planting experiment.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"407\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFactor Combination\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 172px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOverstory Canopy Closure (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eShrub Cover (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eOpen/Shrubs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 172px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eOpen/No Shrubs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 172px;\"\u003e\n \u003cp\u003e13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eShade/Shrubs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 172px;\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 133px;\"\u003e\n \u003cp\u003eShade/No Shrubs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 172px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 102px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3. Mean prefire tree age, plus or minus standard error (\u0026plusmn;SE), and canopy seed storage (number of viable seeds per plot (\u0026plusmn;SE) at our study sites.\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"431\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 107px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSite name\u0026nbsp;\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\u0026nbsp;\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean tree age (year) \u0026plusmn; SE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eViable seeds plot\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003e\u0026plusmn; SE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003eSeiad\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e68 \u0026plusmn; 5\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e91800\u0026nbsp;\u003c/span\u003e\u003cspan dir=\"LTR\"\u003e\u0026plusmn; 39544\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003eIndependence\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e60 \u0026plusmn; 9\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e144059\u0026nbsp;\u003c/span\u003e\u003cspan dir=\"LTR\"\u003e\u0026plusmn; 90171\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003eMud Lake\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e135 \u0026plusmn; 5\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e52602\u0026nbsp;\u003c/span\u003e\u003cspan dir=\"LTR\"\u003e\u0026plusmn; 17378\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 107px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003eLassen\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e56 \u0026plusmn; 6\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp dir=\"RTL\"\u003e\u003cspan dir=\"LTR\"\u003e350609\u0026nbsp;\u003c/span\u003e\u003cspan dir=\"LTR\"\u003e\u0026plusmn; 82247\u003c/span\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 4.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eSummary of best fit generalized linear mixed models that describe the relationships between seedling height and survival, and environmental variables in the final postfire sampling interval (9 years at Lassen, 10 years at Mud Lake).\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"605\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 177px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFixed effect\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter estimate\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eF\u003csub\u003edf\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eR\u003csub\u003em\u003c/sub\u003e\u003csup\u003e2\u0026nbsp;\u003c/sup\u003e(R\u003csub\u003ec\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\" valign=\"top\" style=\"width: 505px;\"\u003e\n \u003cp\u003eSeedling height (millimeters)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e0.28 (0.32)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 177px;\"\u003e\n \u003cp\u003eCanopy Closure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 111px;\"\u003e\n \u003cp\u003e-6.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e6.51\u003csub\u003e1,22\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e0.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 177px;\"\u003e\n \u003cp\u003eShrub Cover\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 111px;\"\u003e\n \u003cp\u003e-2.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e4.09\u003csub\u003e1,23\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 218px;\"\u003e\n \u003cp\u003eSeedling survival (percentage)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 111px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 100px;\"\u003e\n \u003cp\u003e0.5 (0.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 177px;\"\u003e\n \u003cp\u003eCanopy Closure\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 111px;\"\u003e\n \u003cp\u003e-0.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e9.70\u003csub\u003e1,22\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e\u0026lt;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 100px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 177px;\"\u003e\n \u003cp\u003eShrub Cover\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e0.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 84px;\"\u003e\n \u003cp\u003e8.65\u003csub\u003e,22\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e\u0026lt;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\" style=\"width: 41px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 177px;\"\u003e\n \u003cp\u003eRock Cover\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 111px;\"\u003e\n \u003cp\u003e1.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 84px;\"\u003e\n \u003cp\u003e9.28\u003csub\u003e,22\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 92px;\"\u003e\n \u003cp\u003e\u0026lt;0.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"fire-ecology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"feco","sideBox":"Learn more about [Fire Ecology](https://www.springer.com/journal/42408)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/feco/default.aspx","title":"Fire Ecology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Baker cypress, fire severity, immaturity risk, postfire regeneration","lastPublishedDoi":"10.21203/rs.3.rs-7384282/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7384282/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eBaker cypress (\u003cem\u003eHesperocyparis bakeri\u003c/em\u003e (Jeps.) Bartel) is a serotinous conifer associated with high severity fire regimes. Until recently, observations of wildfire effects to Baker cypress populations were rare. There was little direct evidence of fire effects on germination immediately after fires or on population dynamics over longer time frames. We sampled four Baker cypress populations that burned in wildfires between 2006 and 2017 to evaluate postfire germination. We continued data collection at two sites and established a third experimental site to identify factors that contribute to the survival, growth, and health of Baker cypress seedlings over time.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eAlthough Baker cypress is associated with high severity fire regimes, we found that the effects of fire severity were complex and included both positive and negative, as well as short and long-term effects. Germination rates were positively related to crown scorch, but negatively affected by char bole height. These findings suggest that while Baker cypress requires heat to open cones, there are limits to the temperature or duration of heat that seeds can tolerate. Although high severity fire is thought to be necessary to create environmental conditions necessary for germination, we found that ground cover variables were not significant predictors of postfire germination rates at our study sites. Over longer time frames (9\u0026ndash;10 years), Baker cypress density, survival, growth, and health were significantly impacted by fire severity and its effect on environmental variables, including overstory canopy closure, rock cover and shrub cover, demonstrating that fire severity has persistent legacy effects on Baker cypress populations.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eIn an era of altered fire regimes, optimizing fire effects to achieve sufficient crown scorch while minimizing fire behavior that causes extensive bole char may help ensure the persistence of Baker cypress populations into the future. This kind of nuanced understanding of the effect of fire on Baker cypress would not have been possible without immediate postfire assessments of fire severity that were not possible until recently.\u003c/p\u003e","manuscriptTitle":"Complex Effects of High Severity Fire on a Serotinous Conifer","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 07:25:15","doi":"10.21203/rs.3.rs-7384282/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-01-15T16:10:47+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-09T21:02:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"301139069680550146161589799559318891854","date":"2025-12-07T21:25:14+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-10T21:41:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"117418563676387043555656173464025492435","date":"2025-09-04T00:32:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"227029260945693925374570061544665615377","date":"2025-09-02T14:46:03+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-02T14:31:36+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-19T23:04:06+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-19T23:03:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"Fire Ecology","date":"2025-08-15T23:45:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"fire-ecology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"feco","sideBox":"Learn more about [Fire Ecology](https://www.springer.com/journal/42408)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/feco/default.aspx","title":"Fire Ecology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"38ff0711-a33c-40bf-a3b6-9a400da388c5","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T16:02:24+00:00","versionOfRecord":{"articleIdentity":"rs-7384282","link":"https://doi.org/10.1186/s42408-026-00489-1","journal":{"identity":"fire-ecology","isVorOnly":false,"title":"Fire Ecology"},"publishedOn":"2026-04-28 15:57:55","publishedOnDateReadable":"April 28th, 2026"},"versionCreatedAt":"2025-09-09 07:25:15","video":"","vorDoi":"10.1186/s42408-026-00489-1","vorDoiUrl":"https://doi.org/10.1186/s42408-026-00489-1","workflowStages":[]},"version":"v1","identity":"rs-7384282","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7384282","identity":"rs-7384282","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}