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- Title
High Nitrate Retention during Winter in Soils of the Hubbard Brook Experimental Forest.
- Authors
Judd, Kristin E.; Likens, Gene E.; Groffman, Peter M.
- Abstract
Stream export of nitrogen (N) as nitrate (NO; the most mobile form of N) from forest ecosystems is thought to be controlled largely by plant uptake of inorganic N, such that reduced demand for plant N during the non-growing season and following disturbances results in increased stream NO export. The roles of microbes and soils in ecosystem N retention are less clear, but are the dominant controls on N export when plant uptake is low. We used a mass balance approach to investigate soil N retention during winter (December through March) at the Hubbard Brook Experimental Forest by comparing NO inputs (atmospheric deposition), internal production (soil microbial nitrification), and stream output. We focused on months when plant N uptake is nearly zero and the potential for N export is high. Although winter months accounted for only 10–15% of annual net nitrification, soil NO production (0.8–1.0 g N m−2 winter−1) was much greater than stream export (0.03–0.19 N m−2 winter−1). Soil NO retention in two consecutive winters was high (96% of combined NO deposition and soil production; year 1) even following severe plant disturbance caused by an ice-storm (84%; year 2) We show that soil NO retention is surprisingly high even when N demand by plants is low. Our study highlights the need to better understand mechanisms of N retention during the non-growing season to predict how ecosystems will respond to high inputs of atmospheric N, disturbance, and climate change.
- Subjects
HUBBARD Brook Experimental Forest (N.H.); NEW Hampshire; NITROGEN; NITRIFICATION; FOREST restoration; BIOTIC communities; LAND-water ecotones; MASS budget (Geophysics); NITROGEN cycle; EXPERIMENTAL forests
- Publication
Ecosystems, 2007, Vol 10, Issue 2, p217
- ISSN
1432-9840
- Publication type
Article
- DOI
10.1007/s10021-007-9027-x