New Perspectives on Nitrogen Cycling in the Temperate and Tropical Americas

1. Front Matter

   Pages i-4

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2. Nιτρον — An etymology of nitrogen and other related words

   • Jorge E. Corredor

   Pages 5-6

3. Contemporary and pre-industrial global reactive nitrogen budgets

   • Elisabeth A. Holland, Frank J. Dentener, Bobby H. Braswell, James M. Sulzman

   Pages 7-43

4. Nitrogen stable isotopic composition of leaves and soil: Tropical versus temperate forests

   • L. A. Martinelli, M. C. Piccolo, A. R. Townsend, P. M. Vitousek, E. Cuevas, W. Mcdowell et al.

   Pages 45-65

5. The globalization of N deposition: ecosystem consequences in tropical environments

   • Pamela A. Matson, William H. Mcdowell, Alan R. Townsend, Peter M. Vitousek

   Pages 67-83

6. A nitrogen budget for late-successional hillslope tabonuco forest, Puerto Rico

   • Tamara J. Chestnut, Daniel J. Zarin, William H. Mcdowell, Michael Keller

   Pages 85-108

7. The impact of accelerating land-use change on the N-Cycle of tropical aquatic ecosystems: Current conditions and projected changes

   • J. A. Downing, M. McClain, R. Twilley, J. M. Melack, J. Elser, N. N. Rabalais et al.

   Pages 109-148

8. Nitrogen yields from undisturbed watersheds in the Americas

   • William M. Lewis Jr., John M. Melack, William H. Mcdowell, Michael Mcclain, Jeffrey E. Richey

   Pages 149-162

9. Nitrogen cycling and anthropogenic impact in the tropical interamerican seas

   • Jorge E. Corredor, Robert W. Howarth, Robert R. Twilley, Julio M. Morell

   Pages 163-178

10. Ecosystem constraints to symbiotic nitrogen fixers: a simple model and its implications

    • Peter M. Vitousek, Christopher B. Field

    Pages 179-202

11. Do top-down and bottom-up controls interact to exclude nitrogen-fixing cyanobacteria from the plankton of estuaries? An exploration with a simulation model

    • Robert W. Howarth, Francis Chan, Roxanne Marino

    Pages 203-231

12. The presence of nitrogen fixing legumes in terrestrial communities: Evolutionary vs ecological considerations

    • Timothy E. Crews

    Pages 233-246

13. Nitrogen limitation in dryland ecosystems: Responses to geographical and temporal variation in precipitation

    • David U. Hooper, Loretta Johnson

    Pages 247-293

Inputs of nitrogen to terrestrial and aquatic ecosystems have increased several-fold over the last one hundred and fifty years, with the steepest increases during the last four decades. The expansion of fertilizer manu­ facture and use, the increase in fossil fuel combustion, the intensification of animal husbandry, and widespread cultivation of N2 fixing crops have all contributed to the dramatic increase in N inputs. The increase has been most rapid in Northern Hemisphere (NH) temperate ecosystems, but presently subtropical and tropical regions of Asia are also experiencing an explosive increase in N inputs to terrestrial ecosystems (W. Chameides, pers. comm. ; Galloway et al. 1996). Projected increases in N deposition for these trop­ ical and subtropical regions, with a high natural background of N inputs, exceed increases projected for temperate and arctic regions (Cleveland et al. submitted; Galloway et al. 1994; Holland & Lamarque 1997a). Compared to biological N fixation, N deposition is becoming a proportionately greater source of N to terrestrial and aquatic ecosystems worldwide (Vitousek et al. 1997). 6 The nitrogen contained in the atmosphere as N , 3. 9 * 10 Tg (Tg = 2 12 10 g), is the largest reservoir of N in the Earth system (Warneck 1988). However, this paper focuses on the nitrogen emissions and deposition that have been transformed from N2 into reactive forms that are biologically avail­ able (e. g. Vitousek et al. 1997).

• bacteria
• combustion
• ecosystem
• ecosystems
• environment
• plankton
• soil

• University of Colorado, Boulder, USA

  Alan R. Townsend

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