Nitrogen but not phosphorus addition afects symbiotic N2 fxation by legumes in natural and semi‑natural grasslands located on four continents

VÁZQUEZ E.; SCHLEUSS P.-M.; BORER E.T.; BUGALHO M.N.; CALDEIRA M.C.; EISENHAUER N.; ESKELINEN A.; FAY P.A.; HAIDER S.; JENTSCH A.; KIRKMAN K.P.; MCCULLEY R.L.; PERI P.L.; PRICE J.; RICHARDS A.E.; RISCH A.C.; ROSCHER C.; SCHÜTZ M.; SEABLOOM E.W.; STANDISH R.J.; STEVENS C.J.; TEDDER M.J.; VIRTANEN R.; SPOHN M.

PLANT AND SOIL

SPRINGER

Lugar: Berlin; Año: 2022 vol. 478 p. 689 - 707

0032-079X

The amount of nitrogen (N) derived from symbiotic N2 fxation by legumes in grasslands might be afected by anthropogenic N and phosphorus (P) inputs, but the underlying mechanisms are not known. We evaluated symbiotic N2 fxation in 17 natural and semi-natural grasslands on four continents that are subjected to the same full-factorial N and P addition experiment, using the 15N natural abundance method. N as well as combined N and P (NP) addition reduced aboveground legume biomass by 65% and 45%, respectively, compared to the control, whereas P addition had no signifcant impact. Addition of N and/or P had no signifcant efect on the symbiotic N2 fxation per unit legume biomass. In consequence, the amount of N fxed annually per grassland area was less than half in the N addition treatments compared to control and P addition, irrespective of whether the dominant legumes were annuals or perennials.