Forest Canopy Uptake of Atmospheric Nitrogen at a Midwestern U.S. Mixed Hardwood Site: Implications for Carbon Storage
Abstract
This study investigates the potential of increased nitrogen (N) deposition to enhance carbon sequestration in temperate mid-latitude forests. We conducted detailed measurements of N deposition and cycling from an AmeriFlux tower in southern Indiana (MMSF). These measurements indicate an average atmosphere-surface N flux of approximately 6 mg-N m-2 d-1 during the 2000 growing season with approximately 40% coming from dry deposition of NH3, HNO3 and particle bound N. Total inorganic-N wet deposition fluxes during the growing season are comparable to those measured at NADP sites located in Indiana, Ohio and Kentucky, but the dominant form is NH4+ at MMSF and NO3- at the NADP sites. Canopy N uptake is often assumed to be negligible compared to root uptake; however, wet deposition and throughfall measurements indicate significant canopy uptake of N (particularly NH4+) with a net canopy exchange of 9-10 kg-N ha-1 estimated for the year. When multiplied by the carbon to nitrogen ratio in leaves and total aboveground biomass, potential enhancement of carbon storage at this site is equivalent to 200-2050 kg C ha-1 y-1.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.B42E..06P
- Keywords:
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- 1615 Biogeochemical processes (4805)