Long-Term Change in the Nitrogen Cycle of Tropical Forests

• Published in: Science (American Association for the Advancement of Science) Vol. 334; no. 6056; pp. 664 - 666
• Main Authors: Hietz, Peter, Turner, Benjamin L., Wanek, Wolfgang, Richter, Andreas, Nock, Charles A., Wright, S. Joseph
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 04.11.2011; The American Association for the Advancement of Science
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; anthropogenic activities; Anthropogenic factors; Atmospherics; Availability; Biological and medical sciences; Deposition; Dry forests; Drying; Ecosystem studies; Emission measurements; emissions; Fertilization; Forest ecosystems; Forestry; Forests; Fundamental and applied biological sciences. Psychology; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Globalization; Growth rings; Human; Leaves; Legumes; Nitrogen; Nitrogen Cycle; Nitrogen dioxide; Nitrogen enrichment; Panama; Plant Leaves; Pollutant emissions; Productivity; rain forests; Rainforests; Stable isotopes; Synecology; Temperate forests; Terrestrial ecosystems; Thailand; Trees; Tropical Climate; Tropical forests; Central America; Thailand; Asia; Panama; America; Forests; Nitrogen cycle; Bioavailability; Tropical zone
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.1211979

Deposition of reactive nitrogen (N) from human activities has large effects on temperate forests where low natural N availability limits productivity but is not known to affect tropical forests where natural N availability is often much greater. Leaf N and the ratio of N isotopes (δ¹⁵N) increased substantially in a moist forest in Panama between ~1968 and 2007, as did tree-ring δ¹⁵N in a dry forest in Thailand over the past century. A decade of fertilization of a nearby Panamanian forest with N caused similar increases in leaf N and δ¹⁵N. Therefore, our results indicate regional increases in N availability due to anthropogenic N deposition. Atmospheric nitrogen dioxide measurements and increased emissions of anthropogenic reactive N over tropical land areas suggest that these changes are widespread in tropical forests.