From Genes to Ecosystems: Mechanisms Controlling Long-Term Ecosystem Response to Nitrogen Deposition

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

From Genes to Ecosystems: Mechanisms Controlling Long-Term Ecosystem Response to Nitrogen Deposition Scientists at Michigan Technological University and the University of Michigan have received funding from NSF to continue a long-term investigation of the effects of chronic nitrogen deposition on northern hardwood forests. The funding continues a long-term field experiment initiated 1993. Four study sites in Michigan, annually receive experimental additions of three grams of nitrate-nitrogen per square meter. After a decade, these forests grow faster, store more carbon, and leak significant quantities of nitrogen and carbon below the rooting zone. During the next three years, the investigators will determine how chronic nitrate additions alter the ability of soil fungi to break down litter and dead wood, leading to increased carbon storage in soils. They will study the way nitrate additions alter the symbiotic relationship between roots and mycorrhizal fungi, potentially allowing trees to allocate more photosynthate to growth. They will examine the effects of increased leaf nitrogen content on photosynthesis, which also can affect tree growth. Finally, they will study the effects of nitrogen additions on stand development (tree growth and mortality) and the accumulation of dead woody debris. This large dead material stores carbon and provides habitat for a more diverse plant and animal community.