Abstract

Insect herbivores are important drivers of ecosystem processes in grasslands, and can mediate the grassland's response to environmental change. For example, recent evidence shows that above- and belowground herbivory, individually and in combination, can modify how a plant community responds to nitrogen (N) eutrophication, an important driver of global change. However, knowledge about how such effects extend to the associated soil food web is lacking. In a mesocosm experiment, we investigated how communities of soil nematodes - an abundant and functionally important group of soil organisms - responded to above- and belowground insect herbivory at contrasting N levels. We found that the strongest influence of above- and belowground herbivory on the nematode community appeared at elevated N. The abundance of root-feeding nematodes increased when either above- or belowground insect herbivores were present at elevated N, but when applied together the two herbivore types cancelled out one another's effect. Additionally, at elevated N aboveground herbivory increased the abundance of fungal-feeders relative to bacterial-feeders, which indicates changes in decomposition pathways induced by N and herbivory. Belowground herbivory increased the abundance of omnivorous nematodes. The shifts in both the herbivorous and detrital parts of the soil food web demonstrate that above- and belowground herbivory does not only mediate the response of the plant community to N eutrophication, but in extension also the soil food web sustained by the plant community. We conclude that feedbacks between effects of above- and belowground herbivory mediate the response of the grassland ecosystem to N eutrophication.

Keywords

aboveground-belowground linkages; soil nematodes; feeding guilds; functional composition; nematode channel ratio

Published in

Oikos
2018, Volume: 127, number: 9, pages: 1272-1279
Publisher: WILEY

SLU Authors

• Borgström, Pernilla

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Bommarco, Riccardo

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Strengbom, Joachim

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Viketoft, Maria

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1111/oik.04763

Permanent link to this page (URI)

https://res.slu.se/id/publ/96445