title: Nitrogen limitation of net primary productivity in terrestrial ecosystems is globally distributed.
abstract: Our meta-analysis of 126 nitrogen addition experiments evaluated nitrogen (N) limitation of net primary production (NPP) in terrestrial ecosystems. We tested the hypothesis that N limitation is widespread among biomes and influenced by geography and climate. We used the response ratio (R approximately equal ANPP(N)/ANPP(ctrl)) of aboveground plant growth in fertilized to control plots and found that most ecosystems are nitrogen limited with an average 29% growth response to nitrogen (i.e., R = 1.29). The response ratio was significant within temperate forests (R = 1.19), tropical forests (R = 1.60), temperate grasslands (R = 1.53), tropical grasslands (R = 1.26), wetlands (R = 1.16), and tundra (R = 1.35), but not deserts. Eight tropical forest studies had been conducted on very young volcanic soils in Hawaii, and this subgroup was strongly N limited (R = 2.13), which resulted in a negative correlation between forest R and latitude. The degree of N limitation in the remainder of the tropical forest studies (R = 1.20) was comparable to that of temperate forests, and when the young Hawaiian subgroup was excluded, forest R did not vary with latitude. Grassland response increased with latitude, but was independent of temperature and precipitation. These results suggest that the global N and C cycles interact strongly and that geography can mediate ecosystem response to N within certain biome types.
authors.affiliation: Department of Earth System Science, University of California, Irvine, California 92054, USA. dlebauer@uci.edu
authors.forename: David S
authors.initials: DS
authors.lastname: LeBauer
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Treseder
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002980:Climate; D017753:Ecosystem; D005308:Fertilizers; D009584:Nitrogen / Q000378:metabolism*; D063245:Plant Development; D010944:Plants / Q000378:metabolism*; D014197:Trees / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005308:Fertilizers; D002244:Carbon; D009584:Nitrogen