Riparian grazing ecology

Stubble height regulations are frequently used to manage livestock grazing of herbaceous riparian vegetation. The objective of this study was to determine the impact of clipped stubble height and time of clipping on production and regrowth of herbaceous riparian vegetation. In June and July of 2000-2003, 2.2 ft2 experimental plots were clipped to stubble heights of 2, 4, or 6 inches, and paired control plots were left unclipped. All plots were clipped to ground level in October and regrowth was calculated by comparing clipped and control plots. Results indicate that 1) height regrowth was associated positively with stubble height and 2) regrowth was less with July compared to June clipping. Annual production was higher with July (3430 lbs/acre) compared to June (3169 lbs/acre) clipping but did not vary by clipping height. Production values for clipped plots were higher than for unclipped plots, indicating compensatory production in response to defoliation. Timing and intensity of defoliation were reliable predictors of regrowth and production performance. Most clipping height x time combinations produced end of season heights sufficient to meet current federal stubble height requirements (i.e., 4 – 6 inches). Our results provide insight on the timing and intensity of defoliation that will allow for adequate regrowth to meet different management objectives. However, other factors such as stream channel morphology, animal selectivity, and annual weather variation will need to be considered. My current research is addressing the impact of similar clipping treatments on root production in riparian communities. Root production is of interest because of the important role roots play in stabilizing banks during high flow events. Without this stabilizing influence, riparian systems are at greater risk for losing bank materials during high flows. Bank damage can lead to stream widening or downcutting of a stream; the net effect of both of the processes is a lowering of the streamside water table and potential loss of riparian plant communities.

Meadow grazing ecology

Mountain meadow communities provide habitat for numerous wildlife species as well as supplying forage for livestock production. Tufted hairgrass is an important species in many of the mid to high elevation meadow communities of the mountain west. At present there is only limited information on the response of this species to grazing. We recently initiated a study to determine the response of this species to defoliation at different times of the season and different intensities (i.e. different stubble heights). This study will address both above and below ground production responses, changes in species composition with grazing and will also document changes in plant physiology (i.e. photosynthesis) that accompany defoliation.

Related publications

Boyd, C.S, and T.J. Svejcar. 2004. Regrowth and production of herbaceous riparian vegetation following defoliation. Journal of Range Management. 57:448-454.

Boyd, C.S. and T.J. Svejcar. 2004. Regrowth and production of riparian sedge/grass communities following defoliation. In 2004 Annual Report. Eastern Oregon Agricultural Research Center, Burns, OR.

Boyd, C.S. and T.J. Svejcar. 2004. Regrowth of herbaceous riparian vegetation following defoliation. In 2004 Progress Report. Eastern Oregon Agricultural Research Center, Burns, OR.