EAPSI: Nitrogen Cycle Responses to Increasing Presence of Parasitic Mistletoes in Australian Eucalypt Forests

Andrews Holly M, Riverside CA

Investigators

Abstract

Australian eucalypt forests are increasingly inundated with mistletoes, in large response to changes in land management. Mistletoes are parasitic plants that reduce the growth of their host eucalyptus trees but also promote increased bird diversity in forests, resulting in conflicting opinions about how mistletoes affect forest function and productivity. Assessing how biologically-important nutrients, such as nitrogen, cycle through forests in response to mistletoe parasitism may give insight into forest health and function. Changes in nitrogen processes resulting from increasing abundance of mistletoe will likely have ramifications for forest health and global climate, and may inform future land management decisions in Australian woodlands and elsewhere. This project, conducted in collaboration with Dr. Elise Pendall at the Hawkesbury Institute for the Environment at Western Sydney University in Australia, will explore the role of mistletoe for nitrogen cycling in eucalyptus woodlands. Dr. Pendall is a renowned ecosystem ecologist known for her work in biogeochemical cycling in response to ecological disturbances. Relatively little is known about the impacts of Amyema miquelii mistletoe litter on decomposition, nitrification, and denitrification processes in woodlands dominated by Eucalyptus moluccana and E. fibrosa found in Cumberland Plain, Australia. Presumably, nitrogen-rich mistletoe litter could increase decomposition rates and serve as a substrate for increased emissions of nitrous oxide (N2O), a potent greenhouse gas. This study will explore how rates of various components of nitrogen cycling respond to increasing proportions of A. miquelii litter in Eucalyptus forests. By analyzing the quality and quantity of litterfall from plants, the soil microbial activity responsible for processing plant litter and its nitrogenous components, and the emissions of N2O from forest soils, the researcher will determine the increasing contribution of A. miquelii to soil processes and nitrogen cycling in previously nitrogen-poor systems. 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 Australian Academy of Science.