American Journal of Botany最新文献_第6页

Inoculation with native, late-successional arbuscular mycorrhizal fungi improves the growth and establishment of desirable forbs in low-quality prairie restoration 接种原生的、演替较晚的丛枝菌根真菌可以促进低质量草原恢复中理想牧草的生长和建立。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-15 DOI: 10.1002/ajb2.70114

Reb L. Bryant, James D. Bever

Premise

Tallgrass prairies are important yet endangered ecosystems of central North America and subjects of many ecological restoration projects. Prairie restorations commonly succeed in establishing native grasses but can stagnate in the early stages of succession with limited diversity and composition of native forbs. Establishment of desirable forbs introduced into grass-dominated restorations can be difficult because of intense competition. Late-successional arbuscular mycorrhizal (AM) fungi cultured from undisturbed, remnant prairies have been shown to improve restoration outcomes, with most previous tests introducing AM fungi during initial establishment of prairie restoration in post-agricultural fields. Much less research has been performed on the benefits of AM fungi in older restorations.

Methods

In this experiment, we determined whether inoculation with native AM fungi would improve the establishment of 12 native prairie forb species in a decades-old, restored prairie dominated by native grasses. We followed the survival and growth of uninoculated and AM fungi-inoculated plants over two growing seasons.

Results

We found that most species, including high-conservation-value species such as purple prairie clover (Dalea purpurea) and lead plant (Amorpha canescens) benefited in terms of increased survival and/or growth.

Conclusions

By showing that inoculation with native, late successional AM fungi improved establishment of desirable native plants even in a decades-old restored prairie, this study adds to confidence in the benefits of native AM fungi to prairie restoration in general, and specifically demonstrates the potential value of native AM fungi to efforts to enrich existing grass-dominated restored prairies with high conservation value plant species.

前提：高草草原是北美中部重要的濒危生态系统，也是许多生态修复项目的主题。草原恢复通常成功地建立了原生牧草，但在演替的早期阶段，由于本地牧草的多样性和组成有限，可能会停滞不前。由于激烈的竞争，在以草为主的恢复中建立理想的牧草是很困难的。从未受干扰的残余草原中培养的晚演代丛枝菌根（AM）真菌已被证明可以改善恢复结果，大多数先前的试验在农业后领域的草原恢复初期引入AM真菌。关于AM真菌在旧修复中的益处的研究要少得多。方法：在已有几十年历史的原生草为主的恢复草原上，研究了接种原生AM真菌是否能促进12种原生草的建立。我们跟踪了未接种和接种AM真菌的植株在两个生长季节的存活和生长情况。结果：我们发现大多数物种，包括高保护价值的物种，如紫色草原三叶草（Dalea purpurea）和铅植物（Amorpha canescens），在生存和/或生长方面都受益。结论：本研究表明，即使在已有几十年历史的恢复草原上，接种原生晚演替AM真菌也能促进理想原生植物的建立，这增加了对原生AM真菌对草原恢复的总体益处的信心，并具体证明了原生AM真菌对丰富现有草为主的恢复草原的潜在价值，以丰富具有高保护价值的植物物种。

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引用次数: 0

Toward a functional understanding of novel fire regimes in tropical forests 对热带森林新型火灾制度的功能理解。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-14 DOI: 10.1002/ajb2.70112

David Pacuk, Peter van der Sleen, Frank J. Sterck, Masha T. van der Sande

Climate change and land-use alterations are driving forest fires to unprecedented frequencies and intensities worldwide. Even wet tropical forests—historically rarely subjected to fire—are increasingly experiencing fire disturbances. The impact of wildfires on these forests is likely large, since many of their tree species are not adapted to fire. The extent of the consequences depends on complex feedback mechanisms between fire and vegetation, with plant functional traits playing a critical role. However, how different traits may drive fire–vegetation dynamics in such ecosystems is poorly understood due to limited consolidation of relevant data. This uncertainty leaves the future of tropical forests in question. In this review, we explore how functional traits influence the feedback between fire and vegetation. Specifically, we examine how functional traits of species shape (1) fire regimes (here considered in terms of fire frequency and intensity) through fuel characteristics, (2) their resistance to fire, and (3) their recovery after fire. Resilience is conceptualized as resistance to biomass loss and capacity for post-disturbance biomass recovery. We provide a comprehensive overview of these traits and 12 mechanisms involved. Since the relative importance of these traits and mechanisms for fire dynamics and species’ fire resilience remains unknown, we conclude by outlining possible scenarios for how novel fire regimes might affect tropical forest resilience. We also identify knowledge gaps and avenues for future research to improve our understanding of fire–vegetation dynamics in tropical forests.

气候变化和土地利用变化正在推动全球森林火灾达到前所未有的频率和强度。即使是潮湿的热带森林——历史上很少遭受火灾——也越来越多地遭受火灾干扰。野火对这些森林的影响可能很大，因为它们的许多树种不适应火灾。影响的程度取决于火与植被之间复杂的反馈机制，其中植物功能性状起着关键作用。然而，由于相关数据的整合有限，人们对这些生态系统中不同的特征如何驱动火-植被动态知之甚少。这种不确定性使热带森林的未来成为问题。本文主要探讨了功能性状对火与植被间反馈的影响。具体来说，我们研究了物种的功能特征如何通过燃料特性塑造(1)火灾状态（这里考虑的是火灾频率和强度），(2)它们对火灾的抵抗力，以及(3)它们在火灾后的恢复。弹性被定义为对生物量损失的抵抗力和扰动后生物量恢复的能力。我们提供了这些特征和涉及的12个机制的全面概述。由于这些特征和机制对火灾动力学和物种的火灾恢复力的相对重要性仍然未知，我们最后概述了新型火灾制度如何影响热带森林恢复力的可能情景。我们还确定了知识缺口和未来研究的途径，以提高我们对热带森林火-植被动态的理解。

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引用次数: 0

Changes in plant flammability-related traits to fire regime characteristics and biomass conditions in the Cerrado 塞拉多地区植物可燃性相关性状与火灾制度特征和生物量条件的变化。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-14 DOI: 10.1002/ajb2.70110

Vagner Zanzarini, Davi R. Rossatto, Alessandra Fidelis

Premise

Flammability-related traits in open savanna plant communities may shift in response to fire frequency (high vs. low) and history (recently vs. fire exclusion). Dead biomass accumulation and moisture content are expected to drive flammability components (combustibility and consumability). We hypothesized that in low fire frequency and fire exclusion areas, dead biomass accumulates, prolonging combustion duration with higher maximum temperatures and biomass consumption. Conversely, greater biomass should enhance combustibility, while higher moisture should dampen it.

Methods

In Cerrado open savannas, we selected areas with high or low fire frequency and areas that were recently burned or excluded from fire for the last 21 years. For grasses, forbs, and shrubs, we measured the following flammability-related traits: moisture content, dead biomass, burn rate, maximum fire temperature, and burned biomass.

Results

Dead biomass remained similar between fire frequencies and histories. Plants burned slowly (~0.5 cm s^–1) in areas where fire frequency was low or excluded. In all areas, ca 60% of the plant biomass was consumed by fire. The percentage of initial dead biomass increased the flammability components until 75% dead biomass, but beyond this threshold, burn rate, temperature, and burned biomass declined. Moisture content consistently reduced temperature and amount of biomass burned.

Conclusions

Areas with fire excluded had slower fire spread but the amount of plant biomass consumed was not substantially lower. The amount of dead biomass has nonlinear relationships with combustibility and consumability, indicating that areas with more biomass accumulation may have lower flammability. Thus, we need to investigate how flammability-related traits vary in plant communities under different fire regimes to understand fire behavior and improve management decisions.

前提：开阔草原植物群落的易燃性相关特征可能会随着火灾频率（高vs低）和历史（最近vs不发生火灾）的变化而变化。预计死生物量的积累和水分含量将驱动可燃性成分（可燃性和消耗性）。我们假设，在低火灾频率和禁火区域，死生物质积累，燃烧时间延长，最高温度和生物质消耗更高。相反，更大的生物量应该增强可燃性，而更高的湿度应该抑制可燃性。方法：在塞拉多开阔的稀树草原上，我们选择了火灾频率高或低的地区，以及最近21年未发生火灾或未发生火灾的地区。对于禾草、牧草和灌木，我们测量了以下与可燃性相关的特性：水分含量、死亡生物量、燃烧速率、最高火灾温度和燃烧生物量。结果：死亡生物量在火灾发生频率和历史上保持相似。在火灾频率低或不发生火灾的地区，植物燃烧缓慢（~0.5 cm s-1）。在所有地区，约60%的植物生物量被火消耗。初始死生物量的百分比增加了可燃性成分，直到死生物量的75%，但超过这个阈值，燃烧速率、温度和燃烧生物量下降。水分含量持续降低温度和生物质燃烧量。结论：排除火灾的地区火势蔓延较慢，但植物生物量消耗并未显著降低。死亡生物量的数量与可燃性和消耗性呈非线性关系，表明生物量积累越多的地区可燃性越低。因此，我们需要研究不同火灾制度下植物群落中易燃性相关特征的变化，以了解火灾行为并改进管理决策。

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引用次数: 0

Fires in rainforests: Quantifying litter bed flammability of cool temperate rainforests in eastern Australia 热带雨林中的火灾：量化澳大利亚东部凉爽温带热带雨林凋落物床的可燃性。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-14 DOI: 10.1002/ajb2.70111

Jamie E. Burton, Trent D. Penman, Ross J. Peacock

Premise

Rainforests are usually too wet to burn, acting as natural barriers to fire spread and as refuges for biodiversity. However, climate change is increasing the risk of fire incursion into rainforests. Our capacity to manage these impacts is hindered by limited research on rainforest flammability.

Methods

Fallen leaf and litter bed samples were collected from cool temperate rainforest and eucalypt forest in Willi Willi and Werrikimbe National Parks, New South Wales, Australia. Litter bed flammability of 13 common temperate rainforest species was measured in the laboratory. The flammability of rainforest litter beds and fire-prone eucalypt forest litter beds were compared for 0.07 m² and 7.2 m² beds. We also examined links between flammability and key structural and chemical leaf traits.

Results

Rainforest species varied in their litter bed flammability; 64% of the species had lower flammability than litter comprising eucalypt leaves, which typically occur in more fire-prone environments. Species with smaller leaves and less leaf cellulose were associated with lower flammability. Rainforest litter beds had slower flame spread rates, smaller flames, and less material consumed compared to eucalypt litter beds.

Conclusions

Fire characteristics in cool temperate rainforests will vary depending on the species composition of the litter bed, which depends on the litterfall composition of the rainforest stand. This study provides key insights into litter bed flammability in cool temperate rainforests in Australia, which will inform decisions on management of wildfires.

前提：热带雨林通常太湿而不能燃烧，作为火灾蔓延的天然屏障和生物多样性的避难所。然而，气候变化正在增加火灾侵入热带雨林的风险。对雨林可燃性的有限研究阻碍了我们管理这些影响的能力。方法：采集澳大利亚新南威尔士州Willi Willi和Werrikimbe国家公园的寒温带雨林和桉树林的落叶和凋落物床样本。在实验室对13种常见温带雨林树种凋落物床的可燃性进行了测量。对0.07 m2和7.2 m2的雨林凋落物床和易火桉树凋落物床的可燃性进行了比较。我们还研究了可燃性与关键结构和化学叶性状之间的联系。结果：热带雨林物种凋落物床可燃性存在差异；64%的物种的可燃性低于含有桉树叶子的凋落物，这通常发生在更容易发生火灾的环境中。具有较小叶片和较少叶片纤维素的物种具有较低的可燃性。与桉树凋落物床相比，雨林凋落物床的火焰传播速度较慢，火焰较小，消耗的材料较少。结论：寒温带雨林的火灾特征取决于凋落物床的物种组成，而凋落物床的物种组成又取决于雨林林分的凋落物组成。这项研究提供了对澳大利亚凉爽温带雨林凋落物床可燃性的关键见解，这将为野火管理的决策提供信息。

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引用次数: 0

Modifications in fire frequency impact belowground plant components in old-growth grasslands, posing risks to their resilience 火灾频率的变化影响了古老草原的地下植物成分，对它们的恢复能力构成了风险。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-10 DOI: 10.1002/ajb2.70108

Aline Bertolosi Bombo, Alessandra Fidelis, Soizig Le Stradic

Premise

In edaphic old-growth grasslands, the low nutrient content of the soil restricts plant species establishment. Additionally, fire remains an important factor in shaping vegetation structure and belowground biomass investment in old-growth grasslands, such as the campos rupestres. However, how fire frequency affects the belowground components of these grasslands remain poorly understood. Addressing this gap is essential for understanding plant resilience and regeneration strategies in fire-prone ecosystems worldwide and advancing trait-based perspectives on plant persistence under recurrent disturbances.

Methods

We compared plant belowground components across three campos rupestres sites differing in fire frequencies (1, 6, and 10 fires in 34 years). At each site, we quantified fine root biomass, specialized belowground organ biomass, bud bank size, bud-bearing organ density, and organ composition to evaluate how repeated fires shape belowground traits related to persistence and regeneration.

Results

High fire frequencies reduced bud bank size and belowground organ density, but altered organ composition: Graminoid and forb rhizomes declined in number, whereas woody rhizomes became more common. Overall, belowground organ biomass increased with increasing fire frequency, but fine root biomass decreased.

Conclusions

Our study indicates that changes in belowground components driven by fire frequency may lead to irreversible shifts in community structure, where very frequent fires can jeopardize the resilience of the campos rupestres. For such systems, novel fire regimes can have devastating effects, threatening biodiversity, compromising conservation status, and reducing ecosystem services.

前提：在原生草地中，土壤的低养分含量限制了植物物种的建立。此外，火仍然是形成植被结构和地下生物量投资的重要因素，如校园鲁柏斯特等古老草原。然而，火灾频率如何影响这些草原的地下成分仍然知之甚少。解决这一差距对于理解全球火灾易发生态系统中植物的恢复力和再生策略，以及在周期性干扰下推进基于性状的植物持久性观点至关重要。方法：我们比较了三个不同火灾频率（34年内1次、6次和10次火灾）的校园火灾地点的植物地下成分。在每个站点，我们量化细根生物量、地下专门器官生物量、芽库大小、发芽器官密度和器官组成，以评估重复火灾如何塑造与持久性和再生相关的地下性状。结果：高火烧频率降低了芽库大小和地下器官密度，但改变了器官组成：禾本科和草本根茎数量减少，木本根茎数量增加；总体而言，随着火灾频率的增加，地下器官生物量增加，而细根生物量减少。结论：由火灾频率驱动的地下成分变化可能导致群落结构发生不可逆转的变化，其中频繁的火灾可能危及校园环境的恢复能力。对于这样的系统，新的火灾制度可能具有破坏性影响，威胁生物多样性，损害保护状况，减少生态系统服务。

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引用次数: 0

A functional trait perspective on restored temperate grassland responses to changing winter insulation and managed disturbance by fire 温带恢复草地对冬季保温层变化和火灾干扰响应的功能性状分析

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-09 DOI: 10.1002/ajb2.70109

Katherine T. Charton, Jonathan J. Henn, Michelle A. Homann, Christopher R. Warneke, Ellen I. Damschen

Premise

Understanding how disturbance regimes influence temperate grasslands is crucial for adapting management strategies to climate change, particularly in response to the loss of winters. The interaction between disturbance and climate can alter winter soil insulation and potentially the plant community. Examining the role of functional traits in determining community outcomes can help inform whether grasslands will remain resilient to climate change or whether management will need to be adapted proactively.

Methods

We analyzed 7 years of data from a restored temperate grassland experiment to assess how the interaction between management type and timing (i.e., unmanaged control, spring burn, fall burn, and fall mow) and winter snow manipulations (i.e., snow reduction, snow control, and snow addition) affects plant community composition and whether functional traits are related to community turnover.

Results

Changes in the plant community were driven mainly by management type and timing, with minimal influence from winter snow manipulations. While greater stress tolerance was associated with colonization when winter soil insulation was low, overall functional traits had a relatively minor relationship with community turnover.

Conclusions

The minimal effects of winter snow manipulations, combined with the community's shift toward stress-tolerant strategies when winter soil insulation was low, suggest that grasslands may be resilient to winter snow loss in the short term. However, limited colonization by species that are not stress tolerant could drive local extinctions over time. Management strategies that support colonization and retain soil insulation, such as spring burns that maintain disturbance while preserving insulating litter, may help prevent longer-term impacts.

前提：了解干扰制度如何影响温带草原对于调整管理策略以适应气候变化至关重要，特别是在应对冬季损失方面。干扰和气候之间的相互作用可以改变冬季土壤绝缘，并可能改变植物群落。检查功能特征在决定群落结果中的作用可以帮助了解草原是否将保持对气候变化的适应能力，或者是否需要主动适应管理。方法：通过对7年的温带草地恢复试验数据的分析，探讨了管理类型、时间（无管理控制、春烧、秋烧、秋割）和冬季雪操作（减雪、控雪、加雪）对植物群落组成的影响，以及功能性状是否与群落更替有关。结果：植物群落的变化主要受管理类型和时间的影响，冬雪的影响较小。当冬季土壤绝缘性较低时，较强的耐受性与定植有关，但总体功能性状与群落更替的关系相对较小。结论：冬季积雪控制的影响很小，加上冬季土壤绝缘性较低时社区向应力耐受性策略的转变，表明草地可能在短期内对冬季积雪损失具有弹性。然而，随着时间的推移，不耐压力的物种的有限殖民可能会导致局部灭绝。支持定植和保持土壤绝缘的管理策略，如春季焚烧，在保持绝缘凋落物的同时保持干扰，可能有助于防止长期影响。

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引用次数: 0

Temperature and the evolution of flower color: A review 温度与花朵颜色的演变：综述。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-07 DOI: 10.1002/ajb2.70106

Elizabeth P. Lacey

Flower colors brighten our natural world. How and why have they evolved? How might ongoing global warming alter their evolutionary trajectories? In this review, I examine the influence of ambient temperature on the evolution of flower color. Given the wide body of literature on pollinator-mediated selection, I restricted the review to temperature-mediated selection and interactions between temperature and two other abiotic factors, drought and light. I focus on flavonoid-based colors because they are widespread, and their biosynthetic pathway is well characterized. Accumulated data suggest that temperature has been a selective factor in determining large- and small-scale geographic patterns in species having genetically fixed flower color and in species with temperature-sensitive plasticity in color. However, it is also clear that we have much to learn about direct and indirect selection on flower color related to ambient temperature and temperature's contributions to phylogenetic color patterns. Therefore, I conclude with questions to help advance understanding about temperature's role in past evolution and present and future changes arising from global warming.

花的颜色照亮了我们的自然世界。它们是如何以及为什么进化的？持续的全球变暖会如何改变它们的进化轨迹？在这篇综述中，我研究了环境温度对花卉颜色演变的影响。鉴于传粉媒介选择的文献很多，我将综述限制在温度介导的选择以及温度与其他两个非生物因素（干旱和光照）的相互作用上。我专注于基于黄酮类化合物的颜色，因为它们广泛存在，并且它们的生物合成途径已经很好地表征了。积累的数据表明，在具有遗传固定颜色的物种和具有温度敏感可塑性的物种中，温度是决定大范围和小范围地理模式的一个选择因素。然而，对于环境温度对花卉颜色的直接和间接选择，以及温度对系统发育颜色模式的影响，我们也有很多需要了解的地方。因此，我总结了一些问题，以帮助进一步了解温度在过去的进化中所起的作用，以及由全球变暖引起的现在和未来的变化。

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引用次数: 0

Environmental versus phylogenetic control of leaf anatomical traits in Fabaceae, across a continental scale 大陆尺度上豆科植物叶片解剖性状的环境与系统发育控制。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-10-01 DOI: 10.1002/ajb2.70105

Kexiang Huang, Ying Li, Jianming Wang, Wanting Liang, Keyu Zhao, Changsheng Long, Nianting Yu, Guowei Yang, Yang Yang, Wenrui Yang, Congcong Liu

Premise

Leaf anatomical traits influence light absorption and gas exchange, thereby impacting plant growth and ecosystem function. However, the relative importance of environmental variables versus phylogenetic history in explaining leaf anatomical trait variation remains unclear.

Methods

We analyzed eight leaf anatomical traits and 14 environmental variables across 141 species of Fabaceae from 62 genera and 108 sites across China, using phylogenetic comparative analyses and variance partitioning.

Results

Our results reveal that the phylogenetic signal in leaf anatomical traits is relatively constant after considering growth form, indicating that phylogenetic conservatism in these traits is not driven by differences among growth forms. The relationships between leaf anatomical traits and environmental variables are stronger, and the regression slopes between them steeper, when phylogenetic history is accounted for. Variance partitioning demonstrates that phylogeny accounts for less trait variation than environmental variables.

Conclusions

The first comprehensive analysis of leaf anatomical trait variation across Fabaceae species at a large spatial scale provides valuable insights into trait-environment relationships and underlines the importance of considering phylogeny to fully understand plant adaptation.

前提：叶片解剖性状影响光吸收和气体交换，从而影响植物生长和生态系统功能。然而，在解释叶片解剖性状变异时，环境变量与系统发育历史的相对重要性尚不清楚。方法：采用系统发育比较分析和方差划分方法，对中国108个地点62属141种豆科植物的8个叶片解剖性状和14个环境变量进行分析。结果：我们的研究结果表明，考虑生长形式后，叶片解剖性状的系统发育信号相对稳定，表明这些性状的系统发育保守性不是由生长形式差异驱动的。当考虑系统发育历史时，叶片解剖性状与环境变量之间的关系更强，回归斜率更陡。方差划分表明，系统发育对性状变异的影响小于环境变量。结论：本研究首次在大空间尺度上对豆科植物叶片解剖性状的变异进行了全面分析，为揭示性状与环境的关系提供了有价值的见解，并强调了考虑系统发育对充分理解植物适应的重要性。

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引用次数: 0

Stacked scattering: The key to bright flowers lies in the mesophyll 层叠散射：鲜艳花朵的关键在于叶肉。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-09-25 DOI: 10.1002/ajb2.70104

Larissa De Paola, Thomas A. Veldhuis, Marjan Kraaij, Doekele G. Stavenga, Kira J. Tiedge, Casper J. van der Kooi

Premise

The coloration of flowers is caused by wavelength-selective absorption by pigments and scattering of light by floral structures. Although the molecular, physiological, and chemical properties of floral pigments have been studied in considerable detail, how floral structures contribute to the visual signal remains largely unknown. A flower can be considered as a stack of layers, where each layer is characterized by specific pigmentation and scattering properties. Quantifying the contribution of different floral layers to visual signalling aids our understanding of the origin and maintenance of Earth's resplendent flora.

Methods

We quantified the contribution of the cuticle, epidermal cell layer, and the mesophyll to the reflection of light by flowers for nasturtium (Tropaeolum majus), a St. John's wort hybrid (Hypericum ‘Hidcote’), and the large-flowered evening primrose (Oenothera glazioviana). The obtained experimental and modelling data allowed the quantification of the absorption and scattering of light by different floral layers.

Results

The mesophyll was by far the strongest reflecting layer. The reflectance from the epidermal layer was minor, and the cuticle reflected a very small percentage of the total. The strong scattering by the mesophyll is caused by its inhomogeneity and thickness.

Conclusions

The strong light-scattering by the mesophyll crucially determines a flower's visual signal, whereas the cuticle and epidermal cells contribute less than generally assumed. Mesophyll thickness, cell properties and inhomogeneity, including porosity, are essential components of the flower's optical toolkit.

前提：花的颜色是由色素对波长的选择性吸收和花结构对光的散射造成的。尽管对花色素的分子、生理和化学性质已经进行了相当详细的研究，但花的结构如何影响视觉信号仍然是一个很大的未知数。一朵花可以被认为是一层一层的堆叠，其中每一层都具有特定的色素沉着和散射特性。量化不同花层对视觉信号的贡献有助于我们理解地球上灿烂的植物群的起源和维持。方法：定量分析了旱金莲（Tropaeolum majus）、金丝桃（Hypericum 'Hidcote）和大花月见草（Oenothera glzioviana）的角质层、表皮细胞层和叶肉对花反射光的贡献。获得的实验和建模数据可以量化不同花层对光的吸收和散射。结果：叶肉是迄今为止最强的反射层。来自表皮层的反射率很小，角质层的反射率占总反射率的比例很小。叶肉的强散射是由叶肉的非均匀性和厚度引起的。结论：叶肉的强光散射决定了花的视觉信号，而角质层和表皮细胞的作用比通常认为的要小。叶肉厚度，细胞特性和不均匀性，包括孔隙度，是花的光学工具包的基本组成部分。

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引用次数: 0

Sequoia and Sequoiadendron: Two paleoendemic megatrees with markedly different adaptive responses to recent high-severity fires 红杉和红杉：两种古特有的巨树，对最近的高严重性火灾有明显不同的适应反应。

IF 2.7 2区生物学 Q2 PLANT SCIENCES

American Journal of Botany

Pub Date : 2025-09-24 DOI: 10.1002/ajb2.70089

Jon E. Keeley, Juli G. Pausas

Premise

Coast redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum) are two iconic paleoendemic species with limited distributions, well known for their spectacular size. Recently, they have been exposed to high-severity crown fires, with starkly contrasting responses.

Methods

We used all available published literature and field observations to understand the responses to fire in an evolutionary context.

Results

Coast redwoods, found in California's coastal rainforests, were highly resilient to high-severity fires, with most trees surviving due to their ability to resprout from the base and trunk, though seedling regeneration was largely lacking. In contrast, giant sequoias, native to the Sierra Nevada, do not resprout, leading to significant tree mortality after very high-severity fires; they released seeds only in patches where some trees survived moderately high-severity fires.

Conclusions

These high-severity fires were novel events for giant sequoias, but not for coast redwoods. Fire suppression has disrupted the natural fire regime in the giant sequoia ecosystem by preventing frequent lightning-caused surface fires, resulting in high-severity fires that killed a substantial number of these giants. In coast redwood forests, infrequent but high-severity crown fires were the norm before burning by Native Americans. Frequent, low-severity burning by Native Americans over the past few hundred years was localized and 20^th-century fire suppression has returned the natural fire regime to these forests. The recent crown fires do not represent a threat to redwood conservation; however, other management goals may require emulating Native American burning practices and in some cases may be best termed cultural restoration.

前提：海岸红杉（Sequoia sempervirens）和巨红杉（Sequoiadendron giganteum）是两个标志性的古特有物种，分布有限，以其壮观的体型而闻名。最近，它们遭遇了严重程度很高的树冠火灾，反应截然不同。方法：我们利用所有可用的已发表的文献和实地观察来了解在进化背景下对火灾的反应。结果：在加利福尼亚沿海雨林中发现的海岸红杉对高度严重的火灾具有高度的弹性，大多数树木存活下来，因为它们能够从基部和树干上重新发芽，尽管幼苗再生在很大程度上缺乏。相比之下，原生于内华达山脉的巨型红杉不会重新发芽，导致在非常严重的火灾后树木大量死亡；他们只在一些树木在中度严重火灾中幸存下来的地方释放种子。结论：这些高度严重的火灾对巨红杉来说是新的事件，但对海岸红杉来说不是。灭火通过阻止频繁的闪电引起的地面火灾，破坏了巨红杉生态系统的自然火灾制度，导致大量巨红杉死亡的高严重性火灾。在海岸红杉林中，在印第安人燃烧之前，很少发生但严重程度很高的树冠火灾是常态。在过去的几百年里，印第安人频繁的、低强度的燃烧是局部的，20世纪的灭火使这些森林恢复了自然的火灾状态。最近的林冠火灾并不代表红木保护的威胁；然而，其他管理目标可能需要模仿美洲土著的焚烧做法，在某些情况下，最好被称为文化恢复。

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