Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis)
AuthorTrowbridge, Amy M
Stoy, Paul C
Adams, Henry D
Law, Darin J
Breshears, David D
Monson, Russell K
AffiliationUniv Arizona, Sch Nat Resources & Environm
Univ Arizona, Dept Ecol & Evolutionary Biol
Univ Arizona, Tree Ring Res Lab
volatile organic compounds
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationTrowbridge, A. M., Stoy, P. C., Adams, H. D., Law, D. J., Breshears, D. D., Helmig, D., & Monson, R. K. (2019). Drought supersedes warming in determining volatile and tissue defenses of piñon pine (Pinus edulis). Environmental Research Letters, 14(6), 065006.
JournalENVIRONMENTAL RESEARCH LETTERS
Rights©2019 The Author(s). Published by IOP Publishing Ltd. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
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AbstractTrees 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 pinon 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 degrees C and a radiative flux of 1000 mu mol 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 degrees 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 pinon 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.
NoteOpen access journal
VersionFinal published version
SponsorsNational Science Foundation, Division of Atmospheric and Geospace Sciences ; USDA National Institute of Food and Agriculture Hatch project [MONB00389, 228396]; National Science Foundation, Division of Integrative Organismal Systems ; National Science Foundation Division of Environmental Biology ; Department of the Energy National Institute for Climate Change Research (Western Region) [DE-FCO2-O6ER64159]; National Science Foundation Macrosystems Biology [EF-1340624, EF-1550756]; Critical Zone Observatories [EAR-1331408]; DIRENet [DEB-0443526]; Biosphere 2 through the Philecology Foundation (Fort Worth, TX); US Environmental Protection Agency (STAR Fellowship Assistance Agreement) [FP-91717801-0]