Overview
My teaching and research focus is to understand the physiological characteristics of plants and microbes that control the interaction of plant and soil communities with the atmosphere. I use a wide range of modern ecological methodologies to understand these processes, but always against a higher-level ecosystem and evolutionary backdrop. My current research focuses on how terrestrial ecosystems respond and contribute to environmental conditions. The underlying motivation for understanding the interrelationship between the terrestrial environment, the atmosphere, and the pedosphere is to predict the response of ecosystems to human-driven alterations (pollution, global climate change, disturbance, etc.).
My goals in teaching and outreach are to both train new scientists to work in the realm of biosphere-atmosphere interactions and to educate the public about these globally important processes. I teach a variety of courses at Cornell including: BioSM 1610 Ecology and the Marine Environment, BioEE 3610 Advanced Ecology, and BioEE 4660 Plant Physiological Ecology, and BioEE 4661 Plant Physiological Ecology, Laboratory.
Research Focus
The research interests of the Sparks lab are very broad and include questions in plant physiological ecology, ecosystem science, and the application of stable isotopes to ecological questions. My own work tends to focus on the exchange of compounds at the boundary between the atmosphere and terrestrial ecosystems. This exchange has profound and controlling effects on plant ecophysiology, ecosystem function and the chemical composition of both the biosphere and atmosphere. Further, the magnitudes of the fluxes between the earth and the atmosphere often control the pool sizes of important elements and compounds held in each, the balance of which are intrinsic to the maintenance of life on earth (e.g., carbon dioxide, nitrogen, ozone and other oxidants, and many others). For example, fluxes of various reactive trace gases between terrestrial ecosystems and the atmosphere exert significant influences on plant performance, tropospheric photochemistry, global climate, terrestrial biogeochemistry and the maintenance of clean air, water and soil. The study of fluxes between the biosphere and atmosphere requires skills in plant and microbial ecophysiology, with its emphasis on the mechanistic controls over flux; biogeochemistry, with its emphasis on the mass balance of biogeochemical cycles; and atmospheric chemistry, with its emphasis on the reactivity and control over turnover times of various atmospheric constituents. My research program at Cornell University focuses on exchange of compounds at the Earths surface with special emphasis on plant and soil based mechanisms of transfer.
As an example, my lab has worked extensively on gas-phase reactive nitrogen compounds for three reasons. First, the input of reactive gaseous nitrogen directly to plants through foliar uptake is a pathway not normally considered in plant physiological ecology. Second, the input (or loss) of gas phase nitrogen is a large and controlling factor in ecosystem nitrogen availability and cycling. Finally, gaseous nitrogen compounds play a central role in controlling the oxidative chemistry of the lower atmosphere and strongly influence regional air quality and global climate.
My lab is also interested in dynamics of many non-nitrogen gas compounds including ozone, methane, and carbon dioxide.
The approaches and systems we use to study these topics vary dramatically. We work in deserts, tropical dry and wet forests, deciduous forests and shrublands and study an array of compounds including reactive and non-reactive nitrogen, carbon dioxide, methane, water vapor, and ozone. We use techniques ranging from eddy covariance and isotopic analysis to molecular methods describing particular biochemical reactions.
In addition, we support many projects using the application of stable isotopes including animal diet, food webs, fluxes, plant ecology, and atmospheric processes.
Publications
- Yi, C., D. E. Anderson, A. A. Turnipseed, S. P. Burns, J. P. Sparks, D. I. Stannard, and R. K. Monson. The contribution of advective fluxes to net ecosystem CO2 exchange in a high-elevation, subalpine fores. Ecological Applications.
- McCalley, C. K.* and J. P. Sparks. Controls over NO and NH3 emissions from Mojave Desert soils. Oecologia.
- Johnson E. G., J.P. Sparks, B. Dzikovski, B.R. Crane, D.M. Gibson, and R. Loria. Plant-pathogenic Streptomyces species produce nitric oxide synthase derived nitric oxide in response to host signals. Chemistry & Biology 15(1):43-50.
- Vallano, D.M.* and J.P. Sparks. Quantifying foliar uptake of gaseous nitrogen dioxide using enriched foliar d15N values. New Phytologist 177:946-955.
- Sparks, J. P., A. J. Walker, A. A. Turnipseed, and A. Guenther. Dry nitrogen deposition estimates over a forest experiencing free air CO2 enrichment. Global Change Biology. 14(4):768-781.
- Joshi, M.V., D.R.D Bignell, E.G. Johnson, J. P. Sparks, D.M. Gibson, R. Loria. The AraC/XylS regulator TxtR modulates thaxtomin biosynthesis and virulence in Streptomyces scabies. Molecular Microbiology 66(3):633-642.
- Derry, L. A., J. P. Sparks and S. Chandra. Ge/Si fractionation by higher plants: mechanisms and applications to biogeochemical cycles. Geochemica et Cosmochimica Acta 71(15):A219-A219 Suppl. S.
- Canny, M. J., J. P. Sparks, C. X. Huang, and M. L. Roderick. Air embolisms exsolving in the transpiration water – the effect of constrictions in the xylem pipes. Functional Plant Biology 34(2):95-111.
- Sparks, J. P. Enhancing the efficiency of nitrogen utilization in plants. The Quarterly Review of Biology. 82(4): Page 422–422,
- Vallano, D. M.* and J. P. Sparks. Foliar 15N signatures as indicators of foliar uptake of atmospheric nitrogen pollution. In: Stable Isotopes as Indicators of Environmental Changes, T. E. Dawson (ed.). pp. 93-109. Academic Press.
- Eller, A. S. D.* and J. P. Sparks. Predicting leaf-level fluxes of ozone and nitrogen dioxide: The relative roles of diffusion and biochemical processes. Plant, Cell, and Environment 29(9):1742‑1750.
- Teklemariam, T. A.* and J. P. Sparks. Leaf fluxes of NO and NO2 in four herbaceous plant species: The role of ascorbic acid. Atmospheric Environment 40(12):2235‑2244.
- Turnipseed, A. A., L. G. Huey, E. Nemitz, R. Stickel, J. Higgs, D. J. Tanner, D. L. Slusher, J. P. Sparks, F. Flocke, and A. Guenther. Eddy covariance fluxes of Peroxyacetyl nitrates (PANs) and NOy to a coniferous forest. Journal of Geophysical Research-Atmospheres 111:D09304, doi:10.1029/2005JD006631.
- Holland, E. A., S. B. Bertman, M. A. Carroll, A. B. Guenther, P. B. Shepson, J. P. Sparks, and J. Lee-Taylor. U.S. nitrogen science plan focuses collaborative efforts. EOS 86(27):253-260.
- Monson, R. K., J. P. Sparks, T. N. Rosenstiel, L. E. Scott-Denton, T. E. Huxman, P. C. Harley, A. A. Turnipseed, S. P. Burns, B. Backlund, and J. Hu. Climatic influences on net ecosystem CO2 exchange during the transition from wintertime carbon source to springtime carbon sink in a high-elevation, subalpine forest. Oecologia 146(1):130-147.
- Althoff, D. M., K. A. Segraves, and J. P. Sparks. Characterizing the interaction between the bogus yucca moth and yuccas: Do bogus yucca moths impact yucca reproductive success? Oecologia 140(2):321‑327.
- Angeles, G., B. Bond, J. S. Boyer, T. Brodribb, J. R. Brooks, M. J. Burns, J. Cavender‑Bares, M. Clearwater, H. Cochard, J. Comstock, S. D. Davis, J. C. Domec, L. Donovan, F. Ewers, B. Gartner, U. Hacke, T. Hinckley, N. M. Holbrook, H. G. Jones, K. Kavanagh, B. Law, J. Lopez-Portillo, C. Lovisolo, T. Martin, J. Martinez-Vilalta, S. Mayr, F. C. Meinzer, P. Melcher, M. Mencuccini, S. Mulkey, A. Nardini, H. S. Neufeld, J. Passioura, W. T. Pockman, R. B. Pratt, S. Rambal, H. Richter, L. Sack, S. Salleo, A. Schubert, P. Schulte, J. P. Sparks, J. Sperry, R. Teskey, and M. Tyree. The cohesion-tension theory. New Phytologist 163(3):451‑452.
- Sparks, J. P. Plant uptake of reactive nitrogen. In: Studying Forest Canopies from Above: The International Canopy Crane Network, Y. Basset, V. Horlyck, and J. Wright (eds.). UNEP & Smithsonian Institution. ISBN 9962-614-05-8.
- Sparks, J. P. Photosynthesis and autotrophic energy flows. In: Encyclopedia of Energy, C. S. Cleveland (ed.). Elsevier, Inc., New York, volume 5, pp. 9-16.
- Sparks, J. P. The herbaceous layer in forests of Eastern North America. The Quarterly Review of Biology 79(3):324.
- Teklemariam, T. A.* and J. P. Sparks. Gaseous fluxes of peroxyacetyl nitrate (PAN) into plant leaves. Plant, Cell, and Environment 27(9):1149-1158.
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