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

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

GLOBAL CHANGE BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

1354-1013

Soil nitrogen (N) availability is critical for grassland functioning. However, human activities haveincreased the supply of biologically-limiting nutrients, and changed the density and identity ofmammalian herbivores. These anthropogenic changes may alter net soil N mineralization (soil netNmin), i.e., the net balance between N mineralization and immobilization, which could severelyimpact grassland structure and functioning. Yet, to date, little is known about how fertilization andherbivore removal individually, or jointly, affect soil net Nmin across a wide range of grasslandsthat vary in soil and climatic properties. Here, we collected data from 22 grasslands on fivecontinents, all part of a globally replicated experiment, to assess how fertilization and herbivoreremoval affected potential (laboratory-based) and realized (field-based) soil net Nmin.Herbivore removal in the absence of fertilization did not alter potential and realized soil net Nmin.However, fertilization alone and in combination with herbivore removal consistently increasedpotential soil net Nmin. Realized soil net Nmin, in contrast, significantly decreased in fertilized plotswhere herbivores were removed. Treatment effects on potential and realized soil net Nmin werecontingent on site-specific soil and climatic properties. Fertilization effects on potential soil netNmin were larger at sites with higher mean annual precipitation (MAP) and temperature of thewettest quarter (T.q.wet). Reciprocally, realized soil net Nmin declined most strongly withfertilization and herbivore removal at sites with lower MAP and higher T.q.wet. In summary, ourfindings show that anthropogenic nutrient enrichment, herbivore exclusion, and alterations infuture climatic conditions can negatively impact soil net Nmin across global grasslands underrealistic field conditions. This is important context-dependent knowledge for grasslandmanagement worldwide.