Contribution of atmospheric nitrogen deposition to net primary productivity in a northern hardwood forest

TitleContribution of atmospheric nitrogen deposition to net primary productivity in a northern hardwood forest
Publication TypeJournal Article
Year of Publication2009
AuthorsNave L, Vogel CS, Gough CM, Curtis PS
JournalCanadian Journal of Forest Research
Volume39
Issue6
Pagination1108 - 1118
Date Published2009
KeywordsNITROGEN
Abstract

Net primary productivity (NPP) in northern temperate forests is an important part of the global carbon cycle. Because NPP often is limited by nitrogen (N), atmospheric N deposition (Ndep) may increase forest NPP. At a northern hardwood forest site in northern Lower Michigan, USA, we quantified rates of N supply by Ndep, canopy retention of Ndep (Ncr), and soil net N mineralization (Nmin); calculated the N requirement of NPP; and estimated the fraction of NPP that could be attributed to atmospheric N inputs. Net N mineralization supplied 42.6kg N·ha-1·year-1 (84% of the NPP N requirement), and Ndep averaged 7.5kg N·ha-1·year-1 (15%). The forest canopy retained 38% of Ndep (Ncr = 2.8kg N·ha-1·year-1), primarily in the forms of organic N and NH4-N. Fine root (62%) and leaf (31%) N requirements dominated the NPP N requirement of 50.7kg N·ha-1·year-1. Annual N supply by the processes we measured agreed very closely with the NPP N requirement, suggesting that internally cycled N and N of atmospheric origin contribute to the N nutrition of this forest. Our results indicate that up to 15% of the NPP at this site may be driven by atmospheric N inputs.

DOI10.1139/X09-038