Below‑ground herbivory mitigates biomass loss from above‑ground herbivory of nitrogen fertilized plants

• Herbivorous insects can infuence grassland ecosystem functions in several ways, notably by alteringprimary production and nutrient turnover. Interactions between above- and belowground herbivorycould afect these functions; an efect that might be modifed by nitrogen (N) addition, an importantglobal change driver. To explore this, we added above- (grasshoppers) and belowground (wireworms)insect herbivores and N into enclosed, equally composed, grassland plant communities in a fullyfactorial feld experiment. N addition substantially altered the impact of above- and belowgroundherbivory on ecosystem functioning. Herbivory and N interacted such that biomass was reduced underabove ground herbivory and high N input, while plant biomass remained stable under simultaneousabove- and belowground herbivory. Aboveground herbivory lowered nutrient turnover rate in thesoil, while belowground herbivory mitigated the efect of aboveground herbivory. Soil decompositionpotential and N mineralization rate were faster under belowground herbivory at ambient N, butat elevated N this efect was only observed when aboveground herbivores were also present. Wefound that N addition does not only infuence productivity directly (repeatedly shown by others), butalso appears to infuence productivity by herbivory mediated efects on nutrient dynamics, whichhighlights the importance of a better understanding of complex biotic interactions.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

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