Grazing-mediated differentiation in Agropyron smithii: Evidence from populations with different grazing histories
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Authors: H. W. Polley, and J. K. Detling
Date: 1990
Journal: Oikos
Volume: 57
Number: 3
Pages: 326-332
Summary of Methods: Polley and Detling collected western wheatgrass (Agropyron smithii) from a heavily grazed area in South Dakota, colonized by black-tailed prairie dogs (Cynomys ludovicianus), and from an adjacent lightly grazed, noncolonized site. Total and residual biomass yields and biomass yields of components of both aboveground and belowground structures were greater in on- than off-colony plants of A. smithii in mixtures across defoliation regimes. Thus, growth rate was greater in on- than off-colony plants in mixtures, as there were no significant differences between populations in initial biomass per plant. Defoliation produced a similar relative reduction in cumulative biomass yield of plants of two populations. Proportional loss of biomass to defoliation was greater in off-colony individuals, which had fewer and larger tillers and greater relative investment of biomass in aboveground components under defoliation, than in on-colony plants. It is suggested that rapid production of small tillers contributes to the prevalence of on-colony growth forms of A. smithii under intensive grazing.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: black-tailed prairie dog, cynomys ludovicianus, western wheatgrass, agropyron smithii, nitrogen, biomass yield
Annotation: 25 pots of interpopulation mixtures were randomly designated for defoliation (both plants per pot defoliated to 4 cm each third week). Plants in the remaining 25 pots were not defoliated.
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