Summary
Plant populations of Schizachyrium scoparium var. frequens with a history of long-term grazing by domestic herbivores were characterized by shorter and narrower leaf blades and tillers of lower weight than plants from populations with a history of no grazing. Following four biweekly defoliation events plants from the grazed populations additionally displayed lower specific leaf weights, lower amounts of biomass removed per tiller upon defoliation and a greater number of new and regrowing tillers. Production values per plant remained similar between the two populations because of a greater number of tillers per plant in the grazed population.
A large amount of allozymic polymorphism was observed in both the grazed and non-grazed populations. Results of the electrophoretic analyses indicated that a minimum of 66% of the plants sampled represented separate genotypes. No distinction could be made between grazed and non-grazed populations in terms of allozymic partitioning. The morphological variation observed between these two populations may represent a shift in the relative dominance of a series of genotypes variously adapted to herbivory.
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Carman, J.G., Briske, D.D. Morphologic and allozymic variation between long-term grazed and non-grazed populations of the bunchgrass Schizachyrium scoparium var. frequens . Oecologia 66, 332–337 (1985). https://doi.org/10.1007/BF00378294
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DOI: https://doi.org/10.1007/BF00378294