Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis)

Amy M. Trowbridge, Paul C. Stoy, Henry D. Adams, Darin J. Law, David D Breshears, Detlev Helmig, Russell Monson

Research output: Contribution to journalArticle

Abstract

Trees are suffering mortality across the globe as a result of drought, warming, and biotic attacks. The combined effects of warming and drought on in situ tree chemical defenses against herbivory have not been studied to date. To address this, we transplanted mature piñon pine trees - a well-studied species that has undergone extensive drought and herbivore-related mortality - within their native woodland habitat and also to a hotter-drier habitat and measured monoterpene emissions and concentrations across the growing season. We hypothesized that greater needle temperatures in the hotter-drier site would increase monoterpene emission rates and consequently lower needle monoterpene concentrations, and that this temperature effect would dominate the seasonal pattern of monoterpene concentrations regardless of drought. In support of our hypothesis, needle monoterpene concentrations were lower across all seasons in trees transplanted to the hotter-drier site. Contrary to our hypothesis, basal emission rates (emission rates normalized to 30 °C and a radiative flux of 1000 μmol m-2 s-1) did not differ between sites. This is because an increase in emissions at the hotter-drier site from a 1.5 °C average temperature increase was offset by decreased emissions from greater plant water stress. High emission rates were frequently observed during June, which were not related to plant physiological or environmental factors but did not occur below pre-dawn leaf water potentials of -2 MPa, the approximate zero carbon assimilation point in piñon pine. Emission rates were also not under environmental or plant physiological control when pre-dawn leaf water potential was less than -2 MPa. Our results suggest that drought may override the effects of temperature on monoterpene emissions and tissue concentrations, and that the influence of drought may occur through metabolic processes sensitive to the overall needle carbon balance.

Original languageEnglish (US)
Article number065006
JournalEnvironmental Research Letters
Volume14
Issue number6
DOIs
StatePublished - Jun 13 2019

Fingerprint

Mesons
Monoterpenes
Pinus
Drought
Droughts
warming
monoterpene
drought
Tissue
Needles
Herbivory
Temperature
Ecosystem
Carbon
Water
Mortality
Dehydration
Thermal effects
tissue
defence

Keywords

  • Drought
  • heat stress
  • monoterpenes
  • Pinus edulis
  • plant defense
  • secondary metabolites
  • volatile organic compounds

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health

Cite this

Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis). / Trowbridge, Amy M.; Stoy, Paul C.; Adams, Henry D.; Law, Darin J.; Breshears, David D; Helmig, Detlev; Monson, Russell.

In: Environmental Research Letters, Vol. 14, No. 6, 065006, 13.06.2019.

Research output: Contribution to journalArticle

Trowbridge, Amy M. ; Stoy, Paul C. ; Adams, Henry D. ; Law, Darin J. ; Breshears, David D ; Helmig, Detlev ; Monson, Russell. / Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis). In: Environmental Research Letters. 2019 ; Vol. 14, No. 6.
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