J Plant Ecol ›› 2020, Vol. 13 ›› Issue (1): 3-11.doi: 10.1093/jpe/rtz040

• Research Articles • Previous Articles     Next Articles

Climatic and fire determinants of early life-history stages in the Mediterranean shrub Cistus albidus

Sandra Saura-Mas1,2, *, Anna Saperas1 and Franciso Lloret1,2   

  1. 1Center for Ecological Research and Forestry Applications (CREAF), E 08193 Bellaterra, Barcelona, Spain
    2Unit of Ecology, Department of Animal and Plant Biology and Ecology, Autonomous University of Barcelona, E-08193 Bellaterra, Barcelona, Spain
  • Received:2018-11-23 Revised:2019-06-04 Accepted:2019-06-29 Online:2019-11-20 Published:2020-02-01

Abstract:

Aims

Cistus albidus reproductive traits have been studied on typical Mediterranean shrublands along a water availability gradient in Northeastern Iberian Peninsula. Germination of this species is known to be highly favoured by fire. Moreover, Mediterranean species are particularly dependent on water availability. Therefore, we establish the hypothesis that in addition to fire disturbance, seedling recruitment in this Mediterranean seeder will be improved in drought-induced episodes resulting in generalized canopy die-off.

Methods

Individuals of several populations of C. albidus were collected and the size, weight and number of fruits and seeds were measured. Germination tests were also carried out on five pre-germination treatments: seeds’ exposure to heat shock, imbibition, two cycles of imbibition/desiccation and the combination of heat shock and imbibition and imbibition/desiccation cycles. Moreover, the number of seedlings after a drought event was surveyed in the field and correlated with canopy die-off.

Important findings

Our study shows the variability of the C. albidus reproductive traits, such as germination rate or fruit production, along the water availability gradient. This variability resulted in a decrease in fruit production but an increase in successful germination under drier conditions. Cistus albidus seeds increased germination with heat, demonstrating their ability to successfully establish after fire. However, recruitment was not exclusively fire dependent since seedling establishment was higher under C. albidus canopies that had collapsed after the extreme drought. Finally, adult density increased C. albidus die-off and mortality, as well as seedling establishment. These results suggest that this species exhibits a trade-off between different reproductive outcomes (i.e. seed production vs. viability), which in turn is determined by climate. This study also provides evidence of how intra-specific competition, climate, particularly drought events and fire disturbance, can determine the success of key early stages of the life history of a common, representative Mediterranean fire-prone seeder shrub.

Key words: seeder, germination, Cistus albidus, life history, Mediterranean, fire, drought, resilience

摘要:
在伊比利亚半岛东北部沿水分梯度的典型地中海灌丛中对白毛岩蔷薇(Cistus albidus)的繁殖性状进行研究。火对该物种的萌发非常 有利。此外,地中海的物种特别依赖于水分有效性。因此,我们建立了一个假说,即除火灾干扰外,该地中海植物的幼苗更新将因干旱事件 得到改善,主要通过干旱事件引发冠层大量死亡。本研究收集了白毛岩蔷薇几个种群的个体,并对果实和种子的大小、重量和数量进行测定 。同时也对五种发芽前处理进行了发芽测试:热激、吸胀、两个吸胀/干燥循环,以及热激和吸胀与吸胀/干燥循环的组合。此外,在野外对 干旱事件后的幼苗数量进行了调查,并与冠层死亡进行相关分析。我们的研究表明,沿水分利用梯度,白毛岩蔷薇繁殖性状(例如发芽率和 果实产量)具有变异性。这种变异性导致干旱条件下果实产量减少而发芽率增加。白毛岩蔷薇种子会因受热增加发芽率,表明它们具有在火 灾后能够成功更新的能力。然而,白毛岩蔷薇种群的增长并不完全取决于火,因为在极端干旱后死亡的白毛岩蔷薇冠层下的幼苗更新率更高 。最后,成年个体密度增加了白毛岩蔷薇的死亡以及幼苗的更新。这些结果表明,该物种在不同的繁殖结果(即种子产量与存活率)间表现 出权衡,而这种权衡又取决于气候。这项研究也为种内竞争、气候(尤其是干旱事件和火干扰)如何影响常见且具有代表性的地中海易火灌 木的生活史关键早期阶段的成功提供了证据。

关键词: 幼苗, 发芽, 白毛岩蔷薇, 生活史, 地中海, 火灾, 干旱, 恢复力

[1] José Djalma de Souza, Bruno Ayron de Souza Aguiar, Danielle Melo dos Santos, Vanessa Kelly Rodrigues de Araujo, Júlia Arruda Simões, Juliana Ramos de Andrade and Elcida de Lima Araújo. Dynamics in the emergence of dormant and non-dormant herbaceous species from the soil seed bank from a Brazilian dry forest [J]. J Plant Ecol, 2020, 13(3): 256-265.
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