New Perspectives on Nitrogen Cycling in the Temperate and Tropical Americas

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 the Temperate and Tropical Americas. More than 40 scientists from 12 different countries met with two principal goals: to compare nitrogen cycling in the relatively pristine temperate zone of South America with the generally more polluted zone of North America; and 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.