Fire synchronizes flowering and boosts reproduction in a widespread but declining prairie species
Fire synchronizes flowering and boosts reproduction in a widespread but declining prairie species
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火灾使分布广泛但数量减少的草原物种同步开花并促进繁殖
DOI：
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发表时间：
2020
影响因子：
11.1
通讯作者：
Gretel Kiefer
中科院分区：
文献类型：
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作者：
S. Wagenius;Jared J. Beck;Gretel Kiefer
意义 我们解决了一个关键的保护问题：依赖火灾的生态系统中本地植物物种的丧失。北美草原等生态系统中火灾频率的减少导致了局部物种的灭绝。主要的假设是，在没有火的情况下，木本和大型草本物种会战胜其他物种。然而，尚未研究替代机制。在我们对草原植物模式植物紫锥菊 (Echinacea angustifolia) 长达 21 年的研究中，我们证明火灾可以同步繁殖，从而增加交配机会并改善繁殖。火灾使开花在年份之间和年内同步，使种子产量几乎翻倍。这些发现证明了一种潜在广泛的机制，通过该机制，火灾可以增强植物繁殖，促进人口增长，并在全世界依赖火灾的生态系统中维持植物多样性。火灾是全球生态系统栖息地结构和生物多样性的重要决定因素。在依赖火灾的社区中，类似于北美大草原，灭火会导致当地植物灭绝。然而，导致物种消失的人口统计机制尚未得到直接调查。我们对 778 株狭叶紫锥菊（一种分布广泛、交配机会长期有限的多年生物种）进行了 21 年的纵向研究，以探索火灾如何影响繁殖。在一个大型保护区，管理单位采用不同的燃烧时间表，我们调查了紫锥菊的交配场景，量化了与潜在交配者的隔离和开花时间的重叠，以确定火灾对有性繁殖潜力的影响程度。我们证明，火通过同步繁殖努力不断增加交配机会。每场火灾都发生在秋季或春季，并在随后的夏季刺激开花，从而使年份之间的繁殖同步并增加火灾后潜在配偶的接近度。火后交配场景中的季节内开花同步性进一步增加了交配潜力。改进的火后交配场景通过提高授粉效率来增强繁殖。火灾后场景中结下的种子比其他场景多 55%，年繁殖力几乎翻倍（增加 88%）。我们预测火灾后同步开花的繁殖效益可以减轻阿利寻找配偶的影响，促进种群增长，并防止紫锥菊和许多其他草原物种的小种群局部灭绝。此外，通过燃烧同步开花可能会改善许多其他植物物种在依赖火的栖息地中的交配机会、繁殖和持续存在的可能性。
Significance We address a critical conservation concern: the loss of native plant species in fire-dependent ecosystems. Reduced fire frequency in ecosystems such as the North American prairie contributes to local extinctions. The leading hypothesis is that woody and large herbaceous species outcompete other species in the absence of fire. However, alternative mechanisms have not been investigated. In our 21-y study of a model prairie plant, Echinacea angustifolia, we demonstrate that fires synchronize reproduction, leading to increased mating opportunities and improved reproduction. Fire synchronizes flowering both among and within years, nearly doubling seed production. These findings demonstrate a potentially widespread mechanism by which fire can enhance plant reproduction, promote population growth, and maintain plant diversity in fire-dependent ecosystems worldwide. Fire is an important determinant of habitat structure and biodiversity across ecosystems worldwide. In fire-dependent communities, similar to the North American prairie, fire suppression contributes to local plant extinctions. Yet the demographic mechanisms responsible for species loss have not been directly investigated. We conducted a 21-y longitudinal study of 778 individual plants of Echinacea angustifolia, a widespread perennial species with chronically limited mating opportunities, to explore how fire affects reproduction. In a large preserve, with management units on different burn schedules, we investigated Echinacea mating scenes, which quantify isolation from potential mates and overlap in the timing of flowering, to determine the extent to which fire influences the potential for sexual reproduction. We demonstrate that fire consistently increased mating opportunities by synchronizing reproductive effort. Each fire occurred during fall or spring and stimulated flowering in the subsequent summer, thus synchronizing reproduction among years and increasing the proximity of potential mates after a fire. Greater within-season flowering synchrony in postfire mating scenes further increased mating potential. The improved postfire mating scene enhanced reproduction by increasing pollination efficiency. Seed set in scenes postfire exceeded other scenes by 55%, and annual fecundity nearly doubled (88% increase). We predict the reproductive benefits of synchronized flowering after fire can alleviate mate-finding Allee effects, promote population growth, and forestall local extirpation in small populations of Echinacea and many other prairie species. Furthermore, the synchronization of flowering by burning may improve mating opportunities, reproduction, and the likelihood of persistence for many other plant species in fire-dependent habitats.