Global impacts of fertilization and herbivore removal on soil net nitrogen mineralization are modulated by local climate and soil properties

RISCH, ANITA C.; SCHÜTZ, MARTIN; FAY, PHILIP A.; BLAIR, JOHN M.; BROWN, CYNTHIA S.; DAVIES, KENDI F.; ESKELINEN, ANU; MCCULLEY, REBECCA L.; POWER, SALLY A.; SIEBERT, JULIA; STEVENS, CARLY J.; YAHDJIAN, LAURA; ZIMMERMANN, STEFAN; HAGEDORN, FRANK; ADLER, PETER B.; BORER, ELIZABETH T.; CADOTTE, MARC W.; VIRGILIO, AUGUSTINA; KNOPS, JOHANNES M. H.; MELBOURNE, BRETT A.; PROBER, SUZANNE M.; SILVEIRA, MARIA L.; TOGNETTI, PEDRO M.; OCHOA?HUESO, RAUL; MOSER, BARBARA; FIRN, JENNIFER; BIEDERMAN, LORI A.; BROADBENT, ARTHUR A. D.; CALDEIRA, MARIA C.; EISENHAUER, NICO; MACDOUGALL, ANDREW S.; MOORE, JOSLIN L.; SEABLOOM, ERIC W.; SPEZIALE, KARINA L.; VIRTANEN, RISTO; RISCH, ANITA C.; SCHÜTZ, MARTIN; FAY, PHILIP A.; BLAIR, JOHN M.; BROWN, CYNTHIA S.; DAVIES, KENDI F.; ESKELINEN, ANU; MCCULLEY, REBECCA L.; POWER, SALLY A.; SIEBERT, JULIA; STEVENS, CARLY J.; YAHDJIAN, LAURA; ZIMMERMANN, STEFAN; HAGEDORN, FRANK; ADLER, PETER B.; BORER, ELIZABETH T.; CADOTTE, MARC W.; VIRGILIO, AUGUSTINA; KNOPS, JOHANNES M. H.; MELBOURNE, BRETT A.

GLOBAL CHANGE BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

1354-1013

Soil nitrogen (N) availability is critical for grassland functioning. However, human activitieshave increased the supply of biologically limiting nutrients, and changed thedensity and identity of mammalian herbivores. These anthropogenic changes mayalter net soil N mineralization (soil net Nmin), that is, the net balance between N mineralizationand immobilization, which could severely impact grassland structure andfunctioning. Yet, to date, little is known about how fertilization and herbivore removalindividually, or jointly, affect soil net Nmin across a wide range of grasslandsthat vary in soil and climatic properties. Here we collected data from 22 grasslandson five continents, all part of a globally replicated experiment, to assess how fertilizationand herbivore removal affected potential (laboratory-based) and realized(field-based) soil net Nmin. Herbivore removal in the absence of fertilization did notalter potential and realized soil net Nmin. However, fertilization alone and in combinationwith herbivore removal consistently increased potential soil net Nmin. Realizedsoil net Nmin, in contrast, significantly decreased in fertilized plots where herbivoreswere removed. Treatment effects on potential and realized soil net Nmin were contingenton site-specific soil and climatic properties. Fertilization effects on potential soilnet Nmin were larger at sites with higher mean annual precipitation (MAP) and temperatureof the wettest quarter (T.q.wet). Reciprocally, realized soil net Nmin declinedmost strongly with fertilization and herbivore removal at sites with lower MAP andhigher T.q.wet. In summary, our findings show that anthropogenic nutrient enrichment,herbivore exclusion and alterations in future climatic conditions can negativelyimpact soil net Nmin across global grasslands under realistic field conditions. This isan important context-dependent knowledge for grassland management worldwide.