A trade-off between embolism resistance and bark thickness in conifers: are drought and fire adaptations antagonistic?

ABSTRACT

Background: Understanding the mechanisms that explain the spatial distribution of conifers across biogeographical gradients is important for anticipating potential range shifts owing to global change. Classical explanations have involved trade-offs between shade and drought tolerances, but more recent studies observed that trade-offs between fire and drought tolerances could also be important.

Aims: Here we propose that a contributing mechanism to explain how conifer species are distributed across productivity gradients – with marked variation in the incidence of fire – involves a trade-off between allocation to bark, which serves to protect against fire, or to embolism resistance, which serves to protect against drought.

Methods: We compiled information from different datasets and performed regression analyses.

Results: We observed a trade-off between bark thickness and embolism resistance in conifer species such that species show either large investments of carbon to the bark or have thinner barks but xylem resistant to embolism; we did not observe conifer species concomitantly showing high fire tolerance and embolism resistance.

Conclusions: This study serves as a starting point for a novel framework on how fire and drought adaptations affect conifer biogeography. Additional studies will be necessary to discover the generality of our findings by including other species of conifers, for example those in the Southern Hemisphere.

Keywords:

• bark
• cavitation
• climate change
• conifers
• fire
• drought
• life strategies
• trade-off

Acknowledgements

We acknowledge funding form the Spanish Government (RYC-2012-10970, AGL2015-69151-R, AGL2015-68274-C3-3-R).

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Ministerio de Economía y Competitividad [RYC-2012-10970, AGL2015-69151-R, AGL2015-68274-C3-].

Notes on contributors

Víctor Resco de Dios

Víctor Resco de Dios is interested in understanding biological processes regulating biosphere-atmosphere interactions.

Carles Arteaga

Carles Arteaga is interested in post-fire regeneration processes.

Javier Hedo

Javier Hedo is interested in understanding the effects of fire on forest soils.

Eustaquio Gil-Pelegrín

Eustaquio Gil-Pelegrín is interested in whole-plant ecophysiology of woody plants, especially in the functional responses of trees and shrubs to drought.

Jordi Voltas

Jordi Voltas is interested in understanding adaptive patterns of Mediterranean conifers and their implications for species resilience under global change.