Effect of grazing history, experimental defoliation, and genotype on patterns of silicification in<i>Agrostis tenuis</i>Sibth.

Bañuelos, María José; Obeso, José Ramón

doi:10.1080/11956860.2000.11682570

Cited by 16 publications

(24 citation statements)

References 18 publications

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“…Some aspects of food quality have been measured with respect to vole population growth (Agrell et al 1995;Klemola et al 2000a), but no studies have examined the effects of silica, the principal defence in their food plants. Although previous studies have found positive correlations between grazing levels and grass silica content (McNaughton & Tarrants 1983, McNaughton et al 1985Brizuela et al 1986;Banuelos & Obeso 2000), we provide the first experimental demonstration that feeding by voles leads directly to dramatic increases in the levels of silica in grass leaves. Hence, this study highlights how silica induction due to grazing could contribute to cyclic dynamics in voles: in years of high population densities, high grazing pressure will lead to induction of silica defences and a subsequent reduction in vole body mass, reproductive outputs and survival.…”

Section: Discussionmentioning

confidence: 86%

Experimental demonstration of the antiherbivore effects of silica in grasses: impacts on foliage digestibility and vole growth rates

2006

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The impact of plant-based factors on the population dynamics of mammalian herbivores has been the subject of much debate in ecology, but the role of antiherbivore defences in grasses has received relatively little attention. Silica has been proposed as the primary defence in grasses and is thought to lead to increased abrasiveness of foliage so deterring feeding, as well as reducing foliage digestibility and herbivore performance. However, at present there is little direct experimental evidence to support these ideas. In this study, we tested the effects of manipulating silica levels on the abrasiveness of grasses and on the feeding preference and growth performance of field voles, specialist grass-feeding herbivores. Elevated silica levels did increase the abrasiveness of grasses and deterred feeding by voles. We also demonstrated, for the first time, that silica reduced the growth rates of both juvenile and mature female voles by reducing the nitrogen they could absorb from the foliage. Furthermore, we found that vole feeding leads to increased levels of silica in leaves, suggesting a dynamic feedback between grasses and their herbivores. We propose that silica induction due to vole grazing reduces vole performance and hence could contribute to cyclic dynamics in vole populations.

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Section: Discussionmentioning

confidence: 86%

Experimental demonstration of the antiherbivore effects of silica in grasses: impacts on foliage digestibility and vole growth rates

2006

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“…Our results demonstrate that both threshold effects and seasonality are important in silicon uptake, and these factors have been found to influence induction in other studies. For example, in a study of Agrostis tenuis , Banuelos & Obeso () found that silicon content of plants was higher in heavily grazed areas than within experimental exclosures during the summer, but no such differences were apparent in winter. This was in contrast to the results from our experimental field enclosures in northern England (Fig.…”

Section: Resultsmentioning

confidence: 99%

The ecology of herbivore‐induced silicon defences in grasses

2016

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Summary1. 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. 2. 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. 3. 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. 4. 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.

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“…Field experiments and studies of naturally-growing grasses showed an induction of increased Si uptake and accumulation in grasses following grazing by rodents [36][37][38], but not by larger mammalian herbivores [1,20,39,40] or following artificial clipping [31]. Induction of increased Si uptake and accumulation among grass species also varies among genotypes and among sites [1,33,39].…”

Section: Herbivorymentioning

confidence: 97%

“…Induction of increased Si uptake and accumulation following herbivory damage has been observed in several grass species, exposed to vertebrate [1,29] and invertebrate [29,30] herbivores, as well as following artificial leaf clipping [22,23,29,31]. Nonetheless, this induction was not observed in some laboratory experiments that were conducted on other grass species exposed to locusts [32] and artificial clipping [29,31,[33][34][35], possibly because exposure periods were too short to initiate a Si uptake response or to allow Si accumulation [29]. In their literature survey, Quigley and Anderson [33] show that although increased Si uptake and deposition is commonly observed in plants that are exposed to real herbivores, exceptions are not rare.…”

Section: Herbivorymentioning

confidence: 99%

Plant Silicon and Phytolith Contents as Affected by Water Availability and Herbivory: Integrating Laboratory Experimentation and Natural Habitat Studies

Katz

Lev‐Yadun

Bar

2015

Silicon

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Purpose When studying the effects of environmental variables on plant Si contents, results of laboratory and field experiments do not always agree with each other. However, new insights into the roles silicon plays in plant life can be gained if both approaches are integrated. Methods Experimental and natural-habitat studies of the effects of water availability and herbivory on plant silicon contents are reviewed and integrated. Results Although higher water availability is expected to have a positive effect on plant silicon contents, naturallygrowing plants often have high silicon contents when grown under drought conditions. Likewise, although experimentation suggests that herbivory has a positive effect on plant silicon contents, such a correlation is not often found in nature. Conclusions Stronger effects of multiple environmental variables or selection in favour of constitutive silicon uptake and deposition as protection from drought and grazing stresses are the reasonable causes of discrepancies between experimental and natural-habitat studies.

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Effect of grazing history, experimental defoliation, and genotype on patterns of silicification inAgrostis tenuisSibth.

Cited by 16 publications

References 18 publications

Experimental demonstration of the antiherbivore effects of silica in grasses: impacts on foliage digestibility and vole growth rates

Experimental demonstration of the antiherbivore effects of silica in grasses: impacts on foliage digestibility and vole growth rates

The ecology of herbivore‐induced silicon defences in grasses

Plant Silicon and Phytolith Contents as Affected by Water Availability and Herbivory: Integrating Laboratory Experimentation and Natural Habitat Studies

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