Biogeochemistry

, Volume 57, Issue 1, pp 239–266

Forest nitrogen sinks in large eastern U.S. watersheds: estimates from forest inventory and an ecosystem model

  • Christine L. Goodale
  • Kate Lajtha
  • Knute J. Nadelhoffer
  • Elizabeth W. Boyer
  • Norbert A. Jaworski
Article

DOI: 10.1023/A:1015796616532

Cite this article as:
Goodale, C.L., Lajtha, K., Nadelhoffer, K.J. et al. Biogeochemistry (2002) 57: 239. doi:10.1023/A:1015796616532

Abstract

The eastern U.S. receives elevated rates of Ndeposition compared to preindustrial times, yetrelatively little of this N is exported indrainage waters. Net uptake of N into forestbiomass and soils could account for asubstantial portion of the difference between Ndeposition and solution exports. We quantifiedforest N sinks in biomass accumulation andharvest export for 16 large river basins in theeastern U.S. with two separate approaches: (1)using growth data from the USDA ForestService's Forest Inventory and Analysis (FIA)program, and (2) using a model of forestnitrogen cycling (PnET-CN) linked to FIAinformation on forest age-class structure. Themodel was also used to quantify N sinks in soiland dead wood, and nitrate losses below therooting zone. Both methods agreed that netgrowth rates were highest in the relativelyyoung forests on the Schuylkill watershed, andlowest in the cool forests of northern Maine. Across the 16 watersheds, wood export removedan average of 2.7 kg N ha−1 yr−1(range: 1–5 kg N ha−1 yr−1), andstanding stocks increased by 4.0 kg N ha−1yr−1 (−3 to 8 kg N ha−1 yr−1). Together, these sinks for N in woody biomassamounted to a mean of 6.7 kg N ha−1yr−1 (2–9 kg N ha−1 yr−1), or73% (15–115%) of atmospheric N deposition. Modeled rates of net N sinks in dead wood andsoil were small; soils were only a significantnet sink for N during simulations ofreforestation of degraded agricultural sites. Predicted losses of nitrate depended on thecombined effects of N deposition, and bothshort- and long-term effects of disturbance. Linking the model with forest inventoryinformation on age-class structure provided auseful step toward incorporating realisticpatterns of forest disturbance status acrossthe landscape.

forest growthforest inventoriesnitrogen budgetnitrogen sinksnitrogen uptakewood production

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Christine L. Goodale
    • 1
  • Kate Lajtha
    • 2
  • Knute J. Nadelhoffer
    • 3
  • Elizabeth W. Boyer
    • 4
  • Norbert A. Jaworski
    • 5
  1. 1.Department of Plant BiologyCarnegie Institution of WashingtonStanford
  2. 2.Department of Botany and Plant Pathology, Oregon State UniversityOregon State UniversityCorvallis
  3. 3.Marine Biological Laboratory, The Ecosystems CenterWoods Hole
  4. 4.College of Environmental Science and ForestryState University of New YorkSyracuse
  5. 5.Retired (US Environmental Protection Agency)Sanford
  6. 6.Woods Hole Research CenterWoods Hole