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Response and Biophysical Regulation of Carbon Fluxes to Climate Variability and Anomaly in Contrasting Ecosystems

Chu, Housen
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418393261

Abstract Details

2014, Doctor of Philosophy, University of Toledo, College of Natural Sciences and Mathematics.
Severe weather and climate anomalies have been observed increasingly in recent decades in United States. Large uncertainties still exist about to what extent ecosystems may respond to such drastic variability of external environmental forcing in terms of their carbon sequestration rates. Challenges also remain in predicting and assessing the potential impact of climate variability and anomaly under anticipated climate change. This study targeted the three most prevalent ecosystems (i.e., a deciduous woodland, a conventional cropland, and a coastal freshwater marsh) in northwestern Ohio, USA. Using the eddy covariance method and supplementary measurements, I examined the effects of recent climatic variability and anomalies (2011-2013) on ecosystem carbon fluxes (i.e., net ecosystem CO2/CH4 exchanges (FCO2/FCH4) and lateral hydrologic fluxes of dissolved organic carbon (FDOC), particulate organic carbon (FPOC), and dissolve inorganic carbon (FDIC)). Gross ecosystem production (GEP) and ecosystem respiration (ER) were the two largest fluxes in the annual carbon budget at all three ecosystems. Yet, these two fluxes compensated each other to a large extent and their balance – FCO2 – depended largely on the interannual variability of these two large fluxes. Around 57-58%, 91-96%, and 77-78% of the interannual FCO2 variability was attributed to functional changes of ecosystems among years, suggesting that the changes of ecosystem structural, physiological, or phenological characteristics played an important role in regulating interannual variability of GEP, ER and FCO2. Freshwater marshes deserve more research attention for their high FCH4 (~50.8±1.0 g C m-2 yr-1) and lateral hydrologic carbon inflows/outflows. Lateral hydrologic flows were an important vector in re-locating carbon among ecosystems in the region. Considerable hydrologic carbon flowed both into and out of the research marsh (108.3±5.4 and 86.2±10.5 g C m-2 yr-1, respectively). Despite marshes accounting for only ~4% of area in this agriculture-dominated landscape, they are potentially efficient in turning over and releasing newly fixed carbon (allochthonous and autochthonous) as CH4 and should be carefully addressed in the regional carbon budget. In sum, this study highlights that different carbon fluxes respond unequally and even oppositely to climate variability and anomaly and thus, their balances may vary largely among ecosystems and years.
Jiquan Chen (Advisor)
Johan Gottgens (Advisor)
Richard Becker (Committee Member)
Ankur Desai (Committee Member)
Ge Sun (Committee Member)
284 p.
Ecology; Environmental Science
Eddy covariance; methane; freshwater marsh; cropland; carbon budget, carbon dioxide, dissolved organic carbon, particulate organic carbon, carbon sequestration; gross ecosystem production; ecosystem respiration; interannual variability; climate anomaly

Recommended Citations

Citations

  • Chu, H. (2014). Response and Biophysical Regulation of Carbon Fluxes to Climate Variability and Anomaly in Contrasting Ecosystems [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418393261

    APA Style (7th edition)

  • Chu, Housen. Response and Biophysical Regulation of Carbon Fluxes to Climate Variability and Anomaly in Contrasting Ecosystems. 2014. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418393261.

    MLA Style (8th edition)

  • Chu, Housen. "Response and Biophysical Regulation of Carbon Fluxes to Climate Variability and Anomaly in Contrasting Ecosystems." Doctoral dissertation, University of Toledo, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1418393261

    Chicago Manual of Style (17th edition)

toledo1418393261
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This open access ETD is published by University of Toledo and OhioLINK.