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Sinks for nitrogen inputs in terrestrial ecosystems: a meta‐analysis of 15 N tracer field studies
Author(s) -
Templer P. H.,
Mack M. C.,
III F. S. Chapin,
Christenson L. M.,
Compton J. E.,
Crook H. D.,
Currie W. S.,
Curtis C. J.,
Dail D. B.,
D'Antonio C. M.,
Emmett B. A.,
Epstein H. E.,
Goodale C. L.,
Gundersen P,
Hobbie S. E.,
Holland K,
Hooper D. U.,
Hungate B. A.,
Lamontagne S,
Nadelhoffer K. J.,
Osenberg C. W.,
Perakis S. S.,
Schleppi P,
Schimel J,
Schmidt I. K.,
Sommerkorn M,
Spoelstra J,
Tietema A,
Wessel W. W.,
Zak D. R.
Publication year - 2012
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/11-1146.1
Subject(s) - ecosystem , terrestrial ecosystem , environmental science , tracer , abundance (ecology) , shrubland , environmental chemistry , δ15n , ecology , δ13c , agronomy , chemistry , stable isotope ratio , biology , nuclear physics , quantum mechanics , physics
Effects of anthropogenic nitrogen (N) deposition and the ability of terrestrial ecosystems to store carbon (C) depend in part on the amount of N retained in the system and its partitioning among plant and soil pools. We conducted a meta‐analysis of studies at 48 sites across four continents that used enriched 15 N isotope tracers in order to synthesize information about total ecosystem N retention (i.e., total ecosystem 15 N recovery in plant and soil pools) across natural systems and N partitioning among ecosystem pools. The greatest recoveries of ecosystem 15 N tracer occurred in shrublands (mean, 89.5%) and wetlands (84.8%) followed by forests (74.9%) and grasslands (51.8%). In the short term (<1 week after 15 N tracer application), total ecosystem 15 N recovery was negatively correlated with fine‐root and soil 15 N natural abundance, and organic soil C and N concentration but was positively correlated with mean annual temperature and mineral soil C:N. In the longer term (3–18 months after 15 N tracer application), total ecosystem 15 N retention was negatively correlated with foliar natural‐abundance 15 N but was positively correlated with mineral soil C and N concentration and C : N, showing that plant and soil natural‐abundance 15 N and soil C:N are good indicators of total ecosystem N retention. Foliar N concentration was not significantly related to ecosystem 15 N tracer recovery, suggesting that plant N status is not a good predictor of total ecosystem N retention. Because the largest ecosystem sinks for 15 N tracer were below ground in forests, shrublands, and grasslands, we conclude that growth enhancement and potential for increased C storage in aboveground biomass from atmospheric N deposition is likely to be modest in these ecosystems. Total ecosystem 15 N recovery decreased with N fertilization, with an apparent threshold fertilization rate of 46 kg N·ha −1 ·yr −1 above which most ecosystems showed net losses of applied 15 N tracer in response to N fertilizer addition.