Data from: The sign of cascading predator effects varies with prey traits in a detrital system

1. Theory and experiments show that the nature of ‘green’ trophic
cascades, between predators, herbivores and plants, varies with several
key species traits: predator hunting mode and predator and prey habitat
domains. Meanwhile, ‘brown’ cascades between predators,
environment-modifying detritivores and plants have been largely overlooked
and the roles of species traits, particularly prey traits, in determining
the nature of these cascades remains unclear. 2. We hypothesize that, in
predator–detritivore–plant interaction chains, the burrowing ability of
plant-facilitating detritivores determines their response to predators and
thus the sign of indirect effect transmitted. In the dung-decomposer food
web of an alpine meadow, we predicted that in the presence of above-ground
predacious beetles: (i) non-burrowing detritivores will suffer mortality
due to predation and transmit negative indirect effects to plants, whereas
(ii) burrowing detritivores will escape predation by retreating deeper
into the soil, transmitting positive indirect effects to plants. 3. In
support of predictions, experiments showed that a single species of
predacious beetle (i) reduced the density of the non-burrowing species and
indirectly reduced dung loss rate, soil nutrient concentrations and plant
biomass, but (ii) drove the burrowing species deeper, indirectly improved
soil conditions and increased plant biomass. 4. These results show that
the burrowing ability of a detritivore can determine whether it transmits
a negative indirect effect mediated by a reduction in its density, or a
positive indirect effect mediated by its behavioural response to predation
risk. 5. We call for further tests of our detritivore-trait hypothesis in
different regions and ecosystems to further develop a general trait-based
framework for trophic cascades in detrital food webs. We further advance
the general hypothesis that the locomotion traits of prey species (e.g.
burrowing/flying ability) may help explain their behavioural response to
predation risk and the nature of indirect effect they transmit from
predators to plants.