In 2004, I completed my doctoral degree at the University of Georgia. My research addressed the roles of direct organic nitrogen (N) uptake in higher plant nutrition and terrestrial ecosystem nutrient cycling. Specifically, I proposed that plant use of organic N, particularly free amino acids (AA), in terrestrial ecosystems is more prevalent than currently perceived. While the extent of AA uptake may depend on a variety of soil and plant factors, AA uptake may act as a general mechanism of plant N acquisition along with mineral N uptake. Preliminary results from both a nutrient cycling model (CNWET) and a pilot field experiment suggested that plants in southeastern temperate wetlands can use soil AA. Because no data had been published to date on AA uptake by plants growing in situ in southeastern temperate terrestrial ecosystems, nor on the ecological implications of AA uptake in these ecosystems, I used stable isotope labeling techniques in field and greenhouse experiments to investigate the generality of AA uptake and to quantify the contribution of directly acquired external AA to plant productivity and nitrogen cycling for four contrasting ecosystems in the Southeast USA (riparian bottomland forest, upland hardwood forest, long-leaf pine savannah, and succeeding old fields).

Please contact me at VJIN@spa.ars.usda.gov