Herbivory and presence of a dominant competitor interactively affect salt marsh plant diversity

DALEO, P.; ALBERTI J.; BRUSCHETTI, M.; MARTINETTO, P; PASCUAL, J.; IRIBARNE, O.

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 28

1100-9233

Question:Do herbivory and the presence of a dominant grass competitorinteractively affect herbaceous communities and assembly rules in aSW Atlantic salt marsh? Location:Upper salt marsh at the Mar Chiquita coastal lagoon (37º 44´52´´ S, 57º 26´ 6´´ W, Argentina).Methods:Weperformed a field factorial experiment, during 4 years, to evaluatethe separate and interactive effects of (1) herbivory and (2)competition with the dominant grass species (i.e. Spartinadensiflora) on saltmarsh subordinate plant community. The factorial design includesdominant grass removal and herbivory manipulation.Results:Our results show that herbivory and presence of the dominantcompetitor interactively affect subordinate plant cover anddiversity. Results further indicate that, in the presence of thedominant competitor, patch-to-patch variation in subordinate speciescomposition is lower than expected at random, a result consistentwith the expected outcomes of deterministic exclusion following lightcompetition. Removal of the dominant grass, nevertheless led topatch-to-patch dissimilarity in subordinate species composition farfrom the dissimilarity expected at random, indicating an increasedimportance of deterministic processes that drive communities todiverge. Conclusion:Our results show that the conditional effect of herbivory on plantdiversity can be determined by the presence of a single plantspecies. Dominant plant species, in addition, may not only affectplant species diversity by determining the number and identity ofsubordinate species in a given patch (i.e. α diversity) but also byaffecting spatial variability by means of habitat homogenization.