title: Long-term change in the nitrogen cycle of tropical forests.
abstract: 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 (δ(15)N) increased substantially in a moist forest in Panama between ~1968 and 2007, as did tree-ring δ(15)N 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 δ(15)N. 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.
authors: Institute of Botany, University of Natural Resources and Life Sciences, Gregor Mendel-Straße 33, 1180 Vienna, Austria. peter.hietz@boku.ac.at
authors: Peter
authors: P
authors: Hietz
authors: Benjamin L
authors: BL
authors: Turner
authors: Wolfgang
authors: W
authors: Wanek
authors: Andreas
authors: A
authors: Richter
authors: Charles A
authors: CA
authors: Nock
authors: S Joseph
authors: SJ
authors: Wright
mesh_terms: D058458:Nitrogen Cycle; D010176:Panama; D018515:Plant Leaves; D013785:Thailand; D014197:Trees; D014329:Tropical Climate