Plant–herbivore interactions and ecological stoichiometry: when do herbivores determine plant nutrient limitation? |
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Authors: | Tanguy Daufresne,& Michel Loreau |
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Affiliation: | Laboratoire d'Ecologie, UMR 7625, Ecole Normale Supérieure, 46, rue d'Ulm, F-75 230 Paris Cedex 05, France. |
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Abstract: | Recent studies on plant–herbivore indirect interactions via nutrient recycling have led to the hypothesis that herbivores with a low nitrogen: phosphorus ratio, feeding on plants with a higher nitrogen: phosphorus ratio, recycle relatively more nitrogen, driving plants into phosphorus limitation. We demonstrate in this paper that such a hypothesis is valid only under restricted conditions, i.e. the nitrogen: phosphorus ratio of inorganic nutrients supplied to the system must be neither too high nor too low compared with the nitrogen: phosphorus ratio of the whole plant + herbivore biomass. If plants have a greater affinity for phosphorus than for nitrogen, low herbivore nitrogen: phosphorus ratio can even promote nitrogen limitation. These results are qualitatively robust, whether grazing functions are donor-controlled or recipient-controlled. We present a graphical analysis of these conditions based on the Zero Net Growth Isocline method. |
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Keywords: | Herbivory stoichiometry nutrient cycling nutrient limitation |
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