Fire and summer temperatures interact to shape seed dormancy thresholds
[Background and Aims]: In Mediterranean ecosystems, the heat shock of wildfire disrupts physical seed dormancy in many plant species. This triggers germination in the post-fire environment where seedling establishment is optimal due to decreased competition and increased resource availability. However, to maintain the soil seed bank until a fire occurs, the minimum heat capable of breaking seed dormancy (i.e. the lower heat threshold) must be above the maximum temperatures typically observed in the soil during the summer. We therefore hypothesized that summer temperatures have shaped heat requirements for physical dormancy release. Specifically, we predicted that seeds from populations growing under warmer summers will have higher values of the lower heat threshold. [Methods]: To evaluate this prediction, we collected seeds from two Cistus species in 31 populations (20 Cistus albidus and 11 Cistus salviifolius) along a climate gradient of summer temperatures on the eastern coast of Spain. For each population, seeds were treated to 10 min heat shocks, from 30 to 120 °C in 5 °C increments (19 treatments), to simulate increasing heat doses from summer to fire-related temperatures. Seeds were then germinated in the lab. [Key Results]: For all populations, maximum germination was observed when applying temperatures associated with fire. Lower heat thresholds varied among populations, with a positive relationship between summer temperatures at seed population origin and the heat dose required to break dormancy. [Conclusions]: Our results suggest that fire drives maximum dormancy release for successful post-fire germination, while summer temperatures determine lower heat thresholds for ensuring inter-fire seed bank persistence. Significant among-population variation of thresholds also suggests that post-fire seeder species have some potential to modify their dormancy release requirements in response to changing climate.
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Oxford University Press
2022-06-18
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Subjects: | Fire, Summer, Mediterranean, Cistaceae, Cistus, Physical seed dormancy, Germination, |
Online Access: | http://hdl.handle.net/10261/303440 |
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dig-cide-es-10261-3034402023-03-16T14:10:04Z Fire and summer temperatures interact to shape seed dormancy thresholds Zomer, Maya Moreira, Bruno Pausas, J. G. Generalitat Valenciana Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination [Background and Aims]: In Mediterranean ecosystems, the heat shock of wildfire disrupts physical seed dormancy in many plant species. This triggers germination in the post-fire environment where seedling establishment is optimal due to decreased competition and increased resource availability. However, to maintain the soil seed bank until a fire occurs, the minimum heat capable of breaking seed dormancy (i.e. the lower heat threshold) must be above the maximum temperatures typically observed in the soil during the summer. We therefore hypothesized that summer temperatures have shaped heat requirements for physical dormancy release. Specifically, we predicted that seeds from populations growing under warmer summers will have higher values of the lower heat threshold. [Methods]: To evaluate this prediction, we collected seeds from two Cistus species in 31 populations (20 Cistus albidus and 11 Cistus salviifolius) along a climate gradient of summer temperatures on the eastern coast of Spain. For each population, seeds were treated to 10 min heat shocks, from 30 to 120 °C in 5 °C increments (19 treatments), to simulate increasing heat doses from summer to fire-related temperatures. Seeds were then germinated in the lab. [Key Results]: For all populations, maximum germination was observed when applying temperatures associated with fire. Lower heat thresholds varied among populations, with a positive relationship between summer temperatures at seed population origin and the heat dose required to break dormancy. [Conclusions]: Our results suggest that fire drives maximum dormancy release for successful post-fire germination, while summer temperatures determine lower heat thresholds for ensuring inter-fire seed bank persistence. Significant among-population variation of thresholds also suggests that post-fire seeder species have some potential to modify their dormancy release requirements in response to changing climate. This work was supported by the Generalitat Valenciana through the program Santiago Grisolia (GRISOLIAP/2017/176), and projects FOCSEC (PROMETEO/2016/021 and FOCSCALES (PROMETEO/2021/040). 2023-03-16T14:10:04Z 2023-03-16T14:10:04Z 2022-06-18 2023-03-16T14:10:04Z artículo doi: 10.1093/aob/mcac047 issn: 0305-7364 e-issn: 1095-8290 Annals of Botany 129(7): 809-816 (2022) http://hdl.handle.net/10261/303440 Publisher's version http://dx.doi.org/10.1093/aob/mcac047 Sí open Oxford University Press |
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Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination |
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Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination Zomer, Maya Moreira, Bruno Pausas, J. G. Fire and summer temperatures interact to shape seed dormancy thresholds |
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[Background and Aims]: In Mediterranean ecosystems, the heat shock of wildfire disrupts physical seed dormancy in many plant species. This triggers germination in the post-fire environment where seedling establishment is optimal due to decreased competition and increased resource availability. However, to maintain the soil seed bank until a fire occurs, the minimum heat capable of breaking seed dormancy (i.e. the lower heat threshold) must be above the maximum temperatures typically observed in the soil during the summer. We therefore hypothesized that summer temperatures have shaped heat requirements for physical dormancy release. Specifically, we predicted that seeds from populations growing under warmer summers will have higher values of the lower heat threshold.
[Methods]: To evaluate this prediction, we collected seeds from two Cistus species in 31 populations (20 Cistus albidus and 11 Cistus salviifolius) along a climate gradient of summer temperatures on the eastern coast of Spain. For each population, seeds were treated to 10 min heat shocks, from 30 to 120 °C in 5 °C increments (19 treatments), to simulate increasing heat doses from summer to fire-related temperatures. Seeds were then germinated in the lab.
[Key Results]: For all populations, maximum germination was observed when applying temperatures associated with fire. Lower heat thresholds varied among populations, with a positive relationship between summer temperatures at seed population origin and the heat dose required to break dormancy.
[Conclusions]: Our results suggest that fire drives maximum dormancy release for successful post-fire germination, while summer temperatures determine lower heat thresholds for ensuring inter-fire seed bank persistence. Significant among-population variation of thresholds also suggests that post-fire seeder species have some potential to modify their dormancy release requirements in response to changing climate. |
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Generalitat Valenciana |
author_facet |
Generalitat Valenciana Zomer, Maya Moreira, Bruno Pausas, J. G. |
format |
artículo |
topic_facet |
Fire Summer Mediterranean Cistaceae Cistus Physical seed dormancy Germination |
author |
Zomer, Maya Moreira, Bruno Pausas, J. G. |
author_sort |
Zomer, Maya |
title |
Fire and summer temperatures interact to shape seed dormancy thresholds |
title_short |
Fire and summer temperatures interact to shape seed dormancy thresholds |
title_full |
Fire and summer temperatures interact to shape seed dormancy thresholds |
title_fullStr |
Fire and summer temperatures interact to shape seed dormancy thresholds |
title_full_unstemmed |
Fire and summer temperatures interact to shape seed dormancy thresholds |
title_sort |
fire and summer temperatures interact to shape seed dormancy thresholds |
publisher |
Oxford University Press |
publishDate |
2022-06-18 |
url |
http://hdl.handle.net/10261/303440 |
work_keys_str_mv |
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1777665630540922880 |