Abstract

In the long-term absence of disturbance, ecosystems often enter a decline or retrogressive phase which leads to reductions in primary productivity, plant biomass, nutrient cycling and foliar quality. However, the consequences of ecosystem retrogression for higher trophic levels such as herbivores and predators, are less clear. Using a post-fire forested island-chronosequence across which retrogression occurs, we provide evidence that nutrient availability strongly controls invertebrate herbivore biomass when predators are few, but that there is a switch from bottom-up to top-down control when predators are common. This trophic flip in herbivore control probably arises because invertebrate predators respond to alternative energy channels from the adjacent aquatic matrix, which were independent of terrestrial plant biomass. Our results suggest that effects of nutrient limitation resulting from ecosystem retrogression on trophic cascades are modified by nutrient-independent variation in predator abundance, and this calls for a more holistic approach to trophic ecology to better understand herbivore effects on plant communities.

Keywords

apparent competition; bottom-up control; cross-ecosystem flows; ecosystem retrogression; exploitation ecosystem hypothesis; plant-herbivore interactions; soil fertility gradient; top-down control

Published in

Ecology Letters
2023, Volume: 26, number: 3, pages: 411-424
Publisher: WILEY

SLU Authors

• Kempel, Anne

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Swiss Federal Institute for Forest, Snow and Landscape Research (WSL)
  • University of Bern

• Wardle, David

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Nanyang Technological University (NTU)

UKÄ Subject classification

Ecology


Publication Identifiers

DOI: https://doi.org/10.1111/ele.14161

Permanent link to this page (URI)

https://res.slu.se/id/publ/121450