Increased root investment can explain the higher survival of seedlings of ‘mesic’ Quercus suber than ‘xeric’ Quercus ilex in sandy soils during a summer drought

José-Alberto Ramírez-Valiente, Ismael Aranda, David Sanchez-Gomez, Jesus Rodriguez-Calcerrada, Fernando Valladares, Thomas Matthew Robson

Research output: Contribution to journalArticleScientificpeer-review

Abstract

In Mediterranean-type ecosystems, drought is considered the main ecological filter for seedling establishment. The evergreen oaks Quercus ilex L. and Quercus suber L. are two of the most abundant tree species in the Mediterranean Basin. Despite their shared evergreen leaf habit and ability to resist low soil water potentials, traditionally it has been suggested that Q. ilex is better suited to resist dry conditions than Q. suber. In this study, we examined how seedlings of Q. ilex and Q. suber grown in sandy soils responded to different levels of water availability using natural dry conditions and supplemental watering. Specifically, we estimated survival and water status of seedlings and explored the role of acorn mass and belowground biomass in seedling performance. To our surprise, Q. suber was better able to survive the summer drought in our experiment than Q. ilex. Nearly 55% of the Q. suber seedlings remained alive after a 2-month period without rain or supplemental water, which represents almost 20% higher survival than Q. ilex over the same period. At the end of the dry period, the surviving seedlings of Q. suber had strikingly higher water potential, potential maximum quantum yield of photosystem II (F-v/F-m) and stomatal conductance (g(s)) than those of Q. ilex. Acorn mass was associated with the probability of survival under dry conditions; however, it did not explain the differences in survival or water status between the species. In contrast, Q. suber had a higher root ratio and root: shoot ratio than Q. ilex and these traits were positively associated with predawn leaf water potential, F-v/F-m, g(s) and survival. Taken together, our results suggest that the higher relative investment in roots by Q. suber when growing in a sandy acidic substrate allowed this species to maintain better physiological status and overall condition than Q. ilex, increasing its probability of survival in dry conditions.

Original languageEnglish
Article numbertpy084
JournalTree Physiology
Volume39
Issue number1
Pages (from-to)64–75
Number of pages12
ISSN0829-318X
DOIs
Publication statusPublished - Jan 2019
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1183 Plant biology, microbiology, virology
  • drought avoidance
  • drought tolerance
  • oaks
  • root depth
  • root ratio
  • seed mass
  • seed size
  • SEED SIZE
  • WATER RELATIONS
  • L. SEEDLINGS
  • STOMATAL RESPONSES
  • MEDITERRANEAN OAKS
  • FIELD PERFORMANCE
  • NUTRIENT STATUS
  • CLIMATE-CHANGE
  • SUBSP BALLOTA
  • TREE

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