Variation in cloud immersion, not precipitation, drives leaf trait plasticity and water relations in vascular epiphytes during an extreme drought

Briana N. Ferguson, Sybil G. Gotsch, Cameron B. Williams, Hannah Wilson, Caitlin N. Barnes, Todd E. Dawson, Nalini M. Nadkarni

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Premise: Epiphytes are abundant in ecosystems such as tropical montane cloud forests where low-lying clouds are often in contact with vegetation. Climate projections for these regions include more variability in rainfall and an increase in cloud base heights, which would lead to drier conditions in the soil and atmosphere. While recent studies have examined the effects of drought on epiphytic water relations, the influence that atmospheric moisture has, either alone or in combination with drought, on the health and performance of epiphyte communities remains unclear. Methods: We conducted a 10-week drought experiment on seven vascular epiphyte species in two shadehouses, one with warmer and drier conditions and another that was cooler and more humid. We measured water relations across control and drought-treatment groups and assessed functional traits of leaves produced during drought conditions to evaluate trait plasticity. Results: Epiphytes exposed to drought and drier atmospheric conditions had a significant reduction in stomatal conductance and leaf water potential and an increase in leaf dry matter. Nonsucculent epiphytes from the drier shadehouse had the greatest shifts in functional traits, whereas succulent epiphytes released stored leaf water to maintain water status. Conclusions: Individuals in the drier shadehouse had a substantial reduction in performance, whereas drought-treated individuals that experienced cloud immersion displayed minimal changes in water status. Our results indicate that projected increases in the cloud base height will reduce growth and performance of epiphytic communities and that nonsucculent epiphytes may be particularly vulnerable.

Original languageEnglish
Pages (from-to)550-563
Number of pages14
JournalAmerican Journal of Botany
Volume109
Issue number4
DOIs
StatePublished - Apr 2022

Bibliographical note

Publisher Copyright:
© 2022 Botanical Society of America.

Keywords

  • Costa Rica
  • Monteverde
  • atmospheric moisture
  • climate change
  • leaf dry matter content
  • lifting cloud base
  • succulence
  • tropical montane cloud forest
  • water potential

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Plant Science

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