Data from: The ecology of herbivore-induced silicon defences in grasses

Silicon as a defence against herbivory in grasses has gained increasing
recognition and has now been studied in a wide range of species, at scales
from individual plants in pots to plant communities in the field. The
impacts of these defences have been assessed on herbivores ranging from
insects to rodents to ungulates. Here, we review current knowledge of
silicon mediation of plant–herbivore interactions in an ecological
context. The production of silicon defences by grasses is affected by both
abiotic and biotic factors and by their interactions. Climate, soil type
and water availability all influence levels of silicon uptake, as does
plant phenology and previous herbivory. The type of defoliation matters
and artificial clipping does not appear to have the same impact on silicon
defence induction as herbivory which includes the presence of saliva.
Induction of silicon defences has been demonstrated to require a threshold
level of damage, both in the laboratory and in the field. In recent
studies of vole–plant interactions, the patterns of induction were found
to be quantitatively similar in glasshouse compared with field
experiments, in terms of both the threshold required for induction and
timing of the induction response. The impacts of silicon defences differ
between different classes of herbivore, possibly reflecting differences in
body size, feeding behaviour and digestive physiology. General patterns
are hard to discern however, and a greater number of studies on wild
mammalian herbivores are required to elucidate these, particularly with an
inclusion of major groups for which there are currently no data, one such
example being marsupials. We highlight new research areas to address what
still remains unclear about the role of silicon as a plant defence,
particularly in relation to plant–herbivore interactions in the field,
where the effects of grazing on defence induction are harder to measure.
We discuss the obstacles inherent in scaling up laboratory work to
landscape-scale studies, the most ecologically relevant but most difficult
to carry out, which is the next challenge in silicon ecology.