Atmosphere-biosphere exchange plays a key role in the global cycles of water and carbon. Air pollution can alter these
processes and induce climate perturbations and feedbacks. Surface ozone (O3) is an air pollutant and greenhouse gas that is toxic to
plants, reducing their growth and ability to regulate water loss. Past controlled experiments have shown that O3 degrades a plant's
water-use efficiency (WUE), which is the ratio of carbon uptake in photosynthesis to water loss in transpiration. This has potentially
significant implications for terrestrial water cycle and precipitation, but no studies have evaluated the O3 effect on WUE in complete
ecosystems. We aim to quantify the impact of O3 on WUE across a wide array of ecosystems. Meteorological and biological data was obtained
from 23 FLUXNET flux tower sites, which use the eddy covariance method to derive hourly fluxes of carbon dioxide (CO2), water vapor (H2O),
and O3 between the atmosphere and ecosystem. Across a broad range of sites, we find a significant negative relationship between daily
anomalies of stomatal O3 flux (FS, O3) and WUE that explains 1-3% of WUE variability. The largest impacts occur in locations and species
with high stomatal conductance, such as broadleaf forests, humid climates, or irrigated crops, rather than where surface O3 concentrations
are highest. Past long-term studies have also found similar O3 impacts (1-3%) on WUE, indicating a consistent response across a pool
species and ecosystems. / A Thesis submitted to the Department of Earth, Ocean, & Atmospheric Science in partial
fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2016. / March 23, 2016. / Ecosystems, FLUXNET, Natural environments, Stomatal ozone flux, Water-use efficiency / Includes bibliographical references. / Christopher D. Holmes, Professor Directing Thesis; Stephanie Pau, Committee Member; Vasu Misra,
Committee Member; Jon Ahlquist, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_360346 |
| Contributors | Ducker, Jason Alexander (authoraut), Holmes, Christopher D. (professor directing thesis), Pau, Stephanie (committee member), Misra, Vasubandhu (committee member), Ahlquist, Jon E. (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean, and Atmospheric Science (degree granting department) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource (115 pages), computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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