Prescribed grazing as a secondary impact in a western riparian floodplain
Journal of Range Management , 44 , 1991

Sedgwick, J.A., Knopf, F.L.

The effect of late-autumn cattle grazing on plant biomass was examined in a western Great Plains cottonwood riparian zone pronet o catastrophicfl oodinge very5 -8 years.F ollowing1 yearo f pre-treatmentd ata collection in 1982, flve 16-ha pasturesw ere grazed from 1982 to 1984 and compared to 5 control pastures within the South Platte River floodplain in northeastern Colorado. At a prescribed grazing level of 0.46 halAUM, riparian vegetation proved to be resilient to the impacts of grazing. We detectedo nly a few significantt reatmente ffectsf or above-ground biomass after succeeding growing seasons. Willows (Salix spp.) responded negatively to grazing whereas biomass of prairie cordgrass( SpartinapectinataL ink)w as greatero n grazedp lots.Y early changesi n above-groundb iomass,e speciallyd ramaticf ollowinga severef lood in 1983,s uggestt hat periodic,c atastrophicf loodingi s a majorp erturbationto the ecosystem,a ndi n conjunctionw itho ur resultso n grazingi mpacts,i ndicatet hat dormant-seasong razing within Soil Conservation Service (SCS) guidelines is a comparatively minor impact within the floodplain. In addition, grazing impacts were probably further mitigated by a major forage supplement of cottonwood leaves which was available at the time of cattle introductions. This local forage supplement ultimately createda lighterg razingt reatment han that originallyp rescribed