Nitrogen but not phosphorus addition affects symbiotic N&lt;sub&gt;2 &lt;/sub&gt;fixation by legumes in natural and semi-natural grasslands located on four continents

Vázquez, Eduardo; Schleuss, Per-Marten; Borer, Elizabeth T.; Bugalho, Miguel N.; Caldeira, Maria C.; Eisenhauer, Nico; Eskelinen, Anu; Fay, Philip A.; Haider, Sylvia; Jentsch, Anke; Kirkman, Kevin P.; McCulley, Rebecca L.; Peri, Pablo L.; Price, Jodi; Richards, Anna E.; Risch, Anita C.; Roscher, Christiane; Schütz, Martin; Seabloom, Eric W.; Standish, Rachel J.; Stevens, Carly J.; Tedder, Michelle J.; Virtanen, Risto; Spohn, Marie

doi:10.1007/s11104-022-05498-y

Nitrogen but not phosphorus addition affects symbiotic N₂fixation by legumes in natural and semi-natural grasslands located on four continents

Vázquez E, Schleuss P-M, Borer ET, Bugalho MN, Caldeira MC, Eisenhauer N, Eskelinen A, Fay PA, Haider S, Jentsch A, Kirkman KP, McCulley RL, Peri PL, Price J, Richards AE, Risch AC, Roscher C, Schütz M, Seabloom EW, Standish RJ, Stevens CJ, Tedder MJ, Virtanen R & Spohn M

Citation

Vázquez, E., Schleuss, P. M., Borer, E. T., Bugalho, M. N., Caldeira, M. C., Eisenhauer, N., … Spohn, M. (2022). Nitrogen but not phosphorus addition affects symbiotic N₂fixation by legumes in natural and semi-natural grasslands located on four continents. Plant and Soil, 478, 689-707. https://doi.org/10.1007/s11104-022-05498-y

Persistent URL https://www.dora.lib4ri.ch/wsl/islandora/object/wsl:30825

Background and aims The amount of nitrogen (N) derived from symbiotic N₂ fixation by legumes in grasslands might be affected by anthropogenic N and phosphorus (P) inputs, but the underlying mechanisms are not known.
Methods We evaluated symbiotic N₂ fixation 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.
Results 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 significant impact. Addition of N and/or P had no significant effect on the symbiotic N₂ fixation per unit legume biomass. In consequence, the amount of N fixed 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.
Conclusion Our results reveal that N addition mainly impacts symbiotic N₂ fixation via reduced biomass of legumes rather than changes in N₂ fixation per unit legume biomass. The results show that soil N enrichment by anthropogenic activities significantly reduces N₂ fixation in grasslands, and these effects cannot be reversed by additional P amendment.