Nitrogen biogeochemistry of three hardwood ecosystems in the Adirondack Region of New York

Myron J. Mitchell, Charles T. Driscoll, Jeffrey S. Owen, Douglas Schaefer, Robert Michener, Dudley J. Raynal

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

The biogeochemistry of nitrogen (N) was evaluated for three forest ecosystems [Woods Lake (WL), Pancake-Hall Creek (PHC) and Huntington Forest (HF)] in the Adirondack region of New York, U.S.A. to evaluate the response of a range of N atmospheric inputs and experimental N additions. Bulk N deposition was higher at sites in the west than those in the central and eastern Adirondacks. These higher atmospheric N inputs were reflected in higher bulk throughfall fluxes of N (WL and PHC, 10.1 and 12.0 kg N ha-1 yr-1, respectively) in the western Adirondacks than at HF (4.6 kg N ha-1 yr-1) in the central Adirondacks. Nitrogen was added to plots as (NH4)2SO4 at 14 and 28 kg N ha-1 yr-1 or as HNO3 at 14 kg N ha-1 yr-1. Litter decomposition rates of Fagus grandifolia and Acer rubrum were substantially higher at WL and PHC compared to HF but were not affected by experimental N additions. Results using mineral soil bags showed no effects of N addition on N and C concentrations in soil organic matter, but C and N concentration increases were less at WL and PHC compared to HF. Soil solution nitrate (NO3-) concentrations at 15-cm depth in the reference plots were higher at PHC than at WL and HF while at 50-cm concentrations were higher at PHC and WL than at HF. The reference plots at the two sites (WL and PHC) with the highest atmospheric inputs of N exhibited lower N retention (53 and 33%, respectively) than HF (68%) in reference plots. The greatest increase in NO3- loss in response to the experimental treatments occurred at HF where the HNO3 additions resulted in the highest NO3- concentrations and lowest N retentions. In contrast, at WL and PHC increases in soil water NO3 - were not evident in response to experimental N additions. The results suggest that the two sites (WL and PHC) in the western Adirondacks did not respond to additional N inputs although they have experienced elevated atmospheric N inputs and higher N drainage losses in reference plots than the HF site in the central Adirondacks. Some of these differences in site response may have also been a function of stand age of WL and PHC that were younger (24 and 33 years, respectively) than the HF (age ∼ 70). Highest NO3- fluxes in the reference plots across the sites corresponded to higher δ15N values in soil and plants. An experimental addition experiment at PHC found that the forest floor and the mineral soil were the largest sinks for experimentally added N.

Original languageEnglish (US)
Pages (from-to)93-133
Number of pages41
JournalBiogeochemistry
Volume56
Issue number2
DOIs
StatePublished - Dec 1 2001

Keywords

  • Atmospheric deposition
  • Decomposition
  • Dissolved organic nitrogen
  • Experimental additions
  • Forests
  • Mass balances
  • N isotopes
  • Nitrate
  • Nitrogen
  • Soils

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology
  • Earth-Surface Processes

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