03637nas a2200229   4500008004100000245007900041210006900120300001500189490000700204520289000211653002503101653002003126653002403146653001003170653001203180653002203192653002303214653002203237100002203259700001903281856010703300       2002                        eng d00aVariation in grazing tolerance among three tallgrass prairie plant species0 aVariation in grazing tolerance among three tallgrass prairie pla  a1634 -16430 v893 aThree tallgrass prairie plant species, two common perennial forbs (Artemisia ludoviciana and Aster ericoides [Asteraceae]) and a dominant C4 perennial grass (Sorghastrum nutans) were studied under field and greenhouse conditions to evaluate interspecific variation in grazing tolerance (compensatory growth capacity). Adaptation to ungulate grazing was also assessed by comparing defoliation responses of plants from populations with a 25-yr history of no grazing or moderate ungulate grazing. Under field conditions, all three species showed significant reductions in shoot relative growth rates (RGR), biomass, and reproduction with defoliation. In the two forbs, clipping resulted in negative shoot RGR and reductions in both number and length of shoot branches per ramet. Sorghastrum nutans maintained positive RGR under defoliation due to a compensatory increase in leaf production. Defoliation reduced rhizome production in A. ericoides and S. nutans, but not in A. ludoviciana. Clipping significantly reduced sexual reproductive allocation in all three species, although S. nutans showed a smaller reduction than the forbs. All three species showed similar responses to defoliation in burned and unburned sites. Under greenhouse conditions, a similar clipping regimen resulted in smaller reductions in growth and reproduction than those observed in the field. For all three species, the grazing tolerance indices calculated under natural field conditions were significantly lower than those estimated from greenhouse-grown plants, and the interspecific patterns of grazing tolerance were different. Aster ericoides exhibited the highest overall defoliation tolerance under greenhouse conditions, followed by S. nutans. Artemisia ludoviciana, the only study species that is typically not grazed by ungulates in the field, showed the lowest grazing tolerance. In the field experiment S. nutans showed the highest grazing tolerance and the two forbs had similar low tolerance indices. These patterns indicate that, despite high compensatory growth potential, limited resource availability and competition in the field significantly reduce the degree of compensation and alter interspecific differences in grazing tolerance among prairie plants. In all three species, defoliation suppressed sexual reproduction more than growth or vegetative reproduction. Significant interactions between plant responses to defoliation and site of origin (historically grazed or ungrazed sites) for some response variables (root/shoot ratios, rhizome bud initiation, and reproductive allocation) indicated some degree of population differentiation and genetic adaptation in response to a relatively short history of ungulate grazing pressure. The results of this study indicate that patterns of grazing tolerance in tallgrass prairie are both genetically based and also environmentally dependent.
10aAmbrosia ludoviciana10aAster ericoides10acompensatory growth10aforbs10aGrasses10agrazing tolerance10aSorghastrum nutans10atallgrass prairie1 aDamhoureyeh, S.A.1 aHartnett, D.C.  uhttp://knz.lternet.edu/content/variation-grazing-tolerance-among-three-tallgrass-prairie-plant-species00535nas a2200133   4500008004100000245007200041210006900113260004300182300001100225490002100236653002200257100002200279856010000301       1999                        eng d00aVariation in grazing tolerance among three tallgrass prairie plants0 aVariation in grazing tolerance among three tallgrass prairie pla  aManhattan, KSbKansas State University  a1 -1320 vPhD Dissertation10atallgrass prairie1 aDamhoureyeh, S.A.  uhttp://knz.lternet.edu/content/variation-grazing-tolerance-among-three-tallgrass-prairie-plants02192nas a2200145   4500008004100000245010400041210006900145300001500214490000700229520169600236653002201932100002201954700001901976856005101995       1997                        eng d00aEffects of bison and cattle on growth, reproduction, and abundances of five tallgrass prairie forbs0 aEffects of bison and cattle on growth reproduction and abundance  a1719 -17280 v843 aForb populations were sampled on Kansas tallgrass prairie to examine the effects of native (bison) and domestic (cattle) ungulates on plant growth, reproduction, and species abundances. Five locally and regionally abundant native tallgrass prairie perennials, Baptisia bracteata, Oenothera speciosa, Vernonia baldwinii, Solidago missouriensis, and Salvia azurea, were selected for study. Replicate watershed-level treatments included three grazing regimes (ungrazed, grazed by cattle, and grazed by bison), and two spring fire frequencies (annually burned and burned at 4-yr intervals). The results show that forb responses to ungulates in tallgrass prairie are complex and vary significantly among plant species, ungulate species, fire regimes, and plant life history stages. Some forbs (e.g., B. bracteata, O. speciosa, and V. baldwinii) increased in growth and reproduction in grazed sites, indicating competitive release in response to selective grazing of the dominant warm-season matrix grasses. Forbs that reduced performance in grazed sites are likely negatively affected by disturbances generated by ungulate nongrazing activities, because none of the forbs studied were directly consumed by bison or cattle. Large grazers had no detectable effect on the frequency of plant damage by other herbivores or pathogens. Significant effects of grazers on patterns of flowering and seed production were not congruent with their effects on population densities, indicating that variation in sexual reproduction plays a minor role in regulating local population abundances. Furthermore, the native and domestic ungulates differ significantly in their effects on forb growth and reproduction.10atallgrass prairie1 aDamhoureyeh, S.A.1 aHartnett, D.C.  uhttp://www.amjbot.org/content/84/12/1719.short00600nas a2200133   4500008004100000245011900041210006900160260004300229300001000272490001400282653002200296100002200318856012600340       1996                        eng d00aEffects of bison and cattle grazing on growth, biomass allocation and reproduction of five tallgrass prairie forbs0 aEffects of bison and cattle grazing on growth biomass allocation  aManhattan, KSbKansas State University  a1 -450 vMS Thesis10atallgrass prairie1 aDamhoureyeh, S.A.  uhttp://knz.lternet.edu/content/effects-bison-and-cattle-grazing-growth-biomass-allocation-and-reproduction-five-tallgrass