CAREER: Direct Foliar Uptake of Atmospheric Nitrogen: Molecular to Ecosystem Considerations

Cornell University, Ithaca NY

Investigators

Abstract

ABSTRACT Jed Spark's five-year CAREER award will establish an integrated research and education plan to investigate exchanges of gaseous reactive nitrogen compounds between the atmosphere and terrestrial ecosystems, the balances of which are intrinsic to the maintenance of life on earth. Sparks and his students will focus on the magnitudes of these exchanges using studies at multiple scales, from the molecular-physiological with emphasis on mechanisms controlling exchanges, to the biogeochemical with emphasis on the mass balance of nitrogen cycles of ecosystems, to atmospheric nitrogen chemistry with emphasis on the reactivity and control over turnover times. This program will enable a new generation of Interdisciplinary scientists to be trained. Reactive nitrogen compounds derive from natural soil driven processes, lightning, emission from fertilizer application, and industrial sources and are of particular interest for three reasons. First, at high concentrations reactive oxidized nitrogen is known to be toxic to plants, although at lower concentrations such compounds have been shown to act as an "atmospheric fertilizer." Second, direct input of nitrogen through leaves into plants is not normally considered by ecologists, while it is conceivable that this could result in both short and long-term effects on photosynthesis, changes in litter quality, and changes in carbon and nitrogen allocation patterns within plants. Finally, nitrogen oxides play a central role in controlling the chemistry of the lower atmosphere by catalyzing the formation of ozone. Sparks will investigate the molecular and physiological mechanisms of foliar nitrogen uptake, quantify the magnitude and controls over canopy-level flux of reactive nitrogen over a range of ecosystems, and support the development of both regional and global biogeochemistry and air-quality models. Additionally, he will implement a two-phase education plan aimed at recruiting and training young scientists. He will first develop a web-based educational platform supported by the Cornell Adult University aimed at recruiting prospective students to the field. He then will support training of young scientists through participation in his research and participation in the Biosphere-Atmosphere Research Training program at the University of Michigan Biological Station. Making linkages between gene expression and biogeochemical processes, as will occur under this award, is a very important part of the future of ecosystem science and a suitably lofty goal as a theme for the early career development of this young scientist.