EAPSI: The Effect of Elevated Nitrogen on Lignin Degrading Microbial Communities in Mt. Changbai Soil

Woo Hannah, Knoxville TN

Investigators

Abstract

This project will investigate the effect of China's pollution on plant litter decomposition. Plant litter consists of dead plant foliage, wood, and roots. Its turnover is an essential process in maintaining organic carbon within soils and is facilitated largely by microorganisms. The unprecedented levels of nitrogen in China due to industrial pollution have drastically increased soil nitrogen concentration. It is unclear how the elevated nitrogen will effect plant litter decomposition and the native microbial communities. Creating laboratory incubations of Mt Changbai field site soil amended with nitrogen, researchers can monitor changes in the composition of plant litter and the microbes involved in plant litter turnover. This research will be conducted in collaboration Dr. Xudong Zhang, a noted expert in soil geochemistry, at the Chinese Academy of Science Institute of Applied Ecology (CAS IAE). Researchers aim to elucidate the long-term impact of elevated nitrogen on forest soil ecosystems because they are important reservoirs of carbon. The project will investigate the effect of elevated nitrogen deposition on the plant litter-degrading microbial community in Mt. Changbai forest soil. This experiment will directly test for the link between stable soil organic carbon lignin and nitrogen deposition. Fresh soil from a field site in the Mt. Changbai will be sampled and amended with lignin and varying concentrations of ammonium nitrate. During incubation, all soil microcosms will be routinely sampled for degraded lignin analysis using alkaline copper oxide. The microcosms will also be sampled weekly for microbial community structure and function analysis via next generation sequencing. Using bioinformatics, samples will be compared to determine differentially abundant species in lignin microcosms at the different levels of nitrogen addition. A better understanding of nitrogen and carbon cycling will lead to better management practices of soil carbon. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Chinese Ministry of Science and Technology.