Predatory beetles facilitate plant growth by driving earthworms to lower soil layers
Article first published online: 19 FEB 2013
© 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society
Journal of Animal Ecology
Volume 82, Issue 4, pages 749–758, July 2013
How to Cite
Zhao, C., Griffin, J. N., Wu, X., Sun, S. (2013), Predatory beetles facilitate plant growth by driving earthworms to lower soil layers. Journal of Animal Ecology, 82: 749–758. doi: 10.1111/1365-2656.12058
- Issue published online: 13 JUN 2013
- Article first published online: 19 FEB 2013
- Manuscript Accepted: 10 JAN 2013
- Manuscript Received: 25 JUL 2012
- 973 program. Grant Number: 2012CB956304
- National Science Foundation of China. Grant Number: 31100387
- National Special Transgenic Project. Grant Number: 2011ZX08012-005
- PCSIRT. Grant Number: IRT1020
- alpine meadow;
- behaviour-mediated indirect interaction;
- food chain;
- trophic cascade
- Theory suggests that predators of soil-improving, plant-facilitating detritivores (e.g. earthworms) should suppress plant growth via a negative tri-trophic cascade, but the empirical evidence is still largely lacking.
- We tested this prediction in an alpine meadow on the Tibetan Plateau by manipulating predatory beetles (presence/absence) and quantifying (i) direct effects on the density and behaviour of earthworms; and (ii) indirect effects on soil properties and above-ground plant biomass.
- In the absence of predators, earthworms improved soil properties, but did not significantly affect plant biomass. Surprisingly, the presence of predators strengthened the positive effect of earthworms on soil properties leading to the emergence of a positive indirect effect of predators on plant biomass.
- We attribute this counterintuitive result to: (i) the inability of predators to suppress overall earthworm density; and (ii) the predator-induced earthworm habitat shift from the upper to lower soil layer that enhanced their soil-modifying, plant-facilitating, effects.
- Our results reveal that plant-level consequences of predators as transmitted through detritivores can hinge on behaviour-mediated indirect interactions that have the potential to overturn predictions based solely on trophic interactions.
- This work calls for a closer examination of the effects of predators in detritus food webs and the development of spatially explicit theory capable of predicting the occurrence and consequences of predator-induced detritivore behavioural shifts.