Ebook: New Perspectives on Nitrogen Cycling in the Temperate and Tropical Americas: Report of the International SCOPE Nitrogen Project

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).

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The global cycle of nitrogen has been altered by human activity to a greater extent than that of any other element. The production of nitrogen fertilizer, cultivation of legumes, and incidental nitrogen fixation in internal combustion engines together transfer more nitrogen from the atmosphere into biologically available forms than is fixed by all natural processes combined. Additionally, biomass burning and land-use change mobilize large quantities of recalcitrant nitrogen into dynamic forms. Although the global change in nitrogen cycling is immense, reactive and biologically available forms of nitrogen do not truly cycle globally. Rather, their transport is over distances of tens to many hundreds of kilometers. Consequently, the alteration of the global nitrogen cycle is manifested as changes at the scale of large regions.
Thus, since 1994 the International SCOPE Nitrogen Project has held a series of workshops focused upon nitrogen dynamics in several different regions of the globe. In May 1996, the Andrew Mellon Foundation and the Inter-American Institute for Global Change (IAI) co-sponsored a SCOPE-N workshop in Termas de Chillan, Chile, entitled A Comparative Analysis of Nitrogen Cycling in theTemperate and Tropical Americas. More than 40 scientists from 12 different countries met with two principal goals: 1) to compare nitrogen cycling in the relatively pristine temperate zone of South America with the generally more polluted zone of North America; and 2) to compare both with nitrogen cycling in the tropical regions of Latin America. This volume presents 12 manuscripts which summarize their efforts during and after the meeting; these papers are rich in new insights and theory. Their conclusions not only advance our understanding of nitrogen dynamics in the Americas, but also of how the global nitrogen cycle responds to the pronounced and continued effects of human activity.

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The global cycle of nitrogen has been altered by human activity to a greater extent than that of any other element. The production of nitrogen fertilizer, cultivation of legumes, and incidental nitrogen fixation in internal combustion engines together transfer more nitrogen from the atmosphere into biologically available forms than is fixed by all natural processes combined. Additionally, biomass burning and land-use change mobilize large quantities of recalcitrant nitrogen into dynamic forms. Although the global change in nitrogen cycling is immense, reactive and biologically available forms of nitrogen do not truly cycle globally. Rather, their transport is over distances of tens to many hundreds of kilometers. Consequently, the alteration of the global nitrogen cycle is manifested as changes at the scale of large regions.
Thus, since 1994 the International SCOPE Nitrogen Project has held a series of workshops focused upon nitrogen dynamics in several different regions of the globe. In May 1996, the Andrew Mellon Foundation and the Inter-American Institute for Global Change (IAI) co-sponsored a SCOPE-N workshop in Termas de Chillan, Chile, entitled A Comparative Analysis of Nitrogen Cycling in theTemperate and Tropical Americas. More than 40 scientists from 12 different countries met with two principal goals: 1) to compare nitrogen cycling in the relatively pristine temperate zone of South America with the generally more polluted zone of North America; and 2) to compare both with nitrogen cycling in the tropical regions of Latin America. This volume presents 12 manuscripts which summarize their efforts during and after the meeting; these papers are rich in new insights and theory. Their conclusions not only advance our understanding of nitrogen dynamics in the Americas, but also of how the global nitrogen cycle responds to the pronounced and continued effects of human activity.
Content:
Front Matter....Pages i-4
N????? — An etymology of nitrogen and other related words....Pages 5-6
Contemporary and pre-industrial global reactive nitrogen budgets....Pages 7-43
Nitrogen stable isotopic composition of leaves and soil: Tropical versus temperate forests....Pages 45-65
The globalization of N deposition: ecosystem consequences in tropical environments....Pages 67-83
A nitrogen budget for late-successional hillslope tabonuco forest, Puerto Rico....Pages 85-108
The impact of accelerating land-use change on the N-Cycle of tropical aquatic ecosystems: Current conditions and projected changes....Pages 109-148
Nitrogen yields from undisturbed watersheds in the Americas....Pages 149-162
Nitrogen cycling and anthropogenic impact in the tropical interamerican seas....Pages 163-178
Ecosystem constraints to symbiotic nitrogen fixers: a simple model and its implications....Pages 179-202
Do top-down and bottom-up controls interact to exclude nitrogen-fixing cyanobacteria from the plankton of estuaries? An exploration with a simulation model....Pages 203-231
The presence of nitrogen fixing legumes in terrestrial communities: Evolutionary vs ecological considerations....Pages 233-246
Nitrogen limitation in dryland ecosystems: Responses to geographical and temporal variation in precipitation....Pages 247-293

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The global cycle of nitrogen has been altered by human activity to a greater extent than that of any other element. The production of nitrogen fertilizer, cultivation of legumes, and incidental nitrogen fixation in internal combustion engines together transfer more nitrogen from the atmosphere into biologically available forms than is fixed by all natural processes combined. Additionally, biomass burning and land-use change mobilize large quantities of recalcitrant nitrogen into dynamic forms. Although the global change in nitrogen cycling is immense, reactive and biologically available forms of nitrogen do not truly cycle globally. Rather, their transport is over distances of tens to many hundreds of kilometers. Consequently, the alteration of the global nitrogen cycle is manifested as changes at the scale of large regions.
Thus, since 1994 the International SCOPE Nitrogen Project has held a series of workshops focused upon nitrogen dynamics in several different regions of the globe. In May 1996, the Andrew Mellon Foundation and the Inter-American Institute for Global Change (IAI) co-sponsored a SCOPE-N workshop in Termas de Chillan, Chile, entitled A Comparative Analysis of Nitrogen Cycling in theTemperate and Tropical Americas. More than 40 scientists from 12 different countries met with two principal goals: 1) to compare nitrogen cycling in the relatively pristine temperate zone of South America with the generally more polluted zone of North America; and 2) to compare both with nitrogen cycling in the tropical regions of Latin America. This volume presents 12 manuscripts which summarize their efforts during and after the meeting; these papers are rich in new insights and theory. Their conclusions not only advance our understanding of nitrogen dynamics in the Americas, but also of how the global nitrogen cycle responds to the pronounced and continued effects of human activity.
Content:
Front Matter....Pages i-4
N????? — An etymology of nitrogen and other related words....Pages 5-6
Contemporary and pre-industrial global reactive nitrogen budgets....Pages 7-43
Nitrogen stable isotopic composition of leaves and soil: Tropical versus temperate forests....Pages 45-65
The globalization of N deposition: ecosystem consequences in tropical environments....Pages 67-83
A nitrogen budget for late-successional hillslope tabonuco forest, Puerto Rico....Pages 85-108
The impact of accelerating land-use change on the N-Cycle of tropical aquatic ecosystems: Current conditions and projected changes....Pages 109-148
Nitrogen yields from undisturbed watersheds in the Americas....Pages 149-162
Nitrogen cycling and anthropogenic impact in the tropical interamerican seas....Pages 163-178
Ecosystem constraints to symbiotic nitrogen fixers: a simple model and its implications....Pages 179-202
Do top-down and bottom-up controls interact to exclude nitrogen-fixing cyanobacteria from the plankton of estuaries? An exploration with a simulation model....Pages 203-231
The presence of nitrogen fixing legumes in terrestrial communities: Evolutionary vs ecological considerations....Pages 233-246
Nitrogen limitation in dryland ecosystems: Responses to geographical and temporal variation in precipitation....Pages 247-293
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