Herbivory and presence of a dominant competitor interactively affect saltmarsh plant diversity

PEDRO DALEO; ALBERTI JUAN; BRUSCHETTI, C.M.; MARTINETTO, P.; PASCUAL JESUS; OSCAR IRIBARNE

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 p. 1178 - 1186

1100-9233

Question: Do herbivory and the presence of a dominant grass competitorinteractively affect herbaceous communities and assembly rules in a SWAtlanticsaltmarsh?Location: Upper saltmarsh,Mar Chiquita coastal lagoon, Argentina.Methods: We performed a field factorial experiment over 4 yr to evaluate theseparate and interactive effects of (1) herbivory and (2) competition with thedominant grass species (i.e. Spartina densiflora) on the salt marsh subordinateplant community. The factorial design includes dominant grass removal andherbivorymanipulation.Results: Our results show that herbivory and presence of the dominant competitorinteractively affect subordinate plant cover and diversity. Results furtherindicate that, in the presence of the dominant competitor, patch-to-patch variationin subordinate species composition is lower than expected at random, aresult consistent with the expected outcomes of deterministic exclusionfollowing light competition. Removal of the dominant grass nevertheless led topatch-to-patch dissimilarity in subordinate species composition, far fromthe dissimilarityexpected at random, indicating increased importance of deterministicprocesses that drive communities to diverge.Conclusion: Our results show that the conditional effect of herbivory on plantdiversity can be determined by the presence of a single plant species. Dominantplant species, in addition, may not only affect plant species diversity bydetermining the number and identity of subordinate species in a given patch(i.e. a-diversity) but also by affecting spatial variability through habitathomogenization.