An Assessment of Metrics to Measure Seasonal Variation in and Grazing Effects on Riparian Plant CommunitiesWestern North American Naturalist (2015)
Several riparian plant community and streambank metrics were evaluated in 5 streams subject to grazing on public lands in central eastern Idaho. In this study, we evaluated 3 attributes associated with the ground cover on streambanks: percent cover of live vegetation, litter, and bare ground; and we evaluated 4 attributes that describe the vegetation community: plant species richness, wetland index value, percent cover of forbs, and percent cover of graminoids. We were particularly interested in how these attributes differed between grazed and ungrazed sites, how the attributes changed through time, and ultimately how the attributes were able to discriminate the effects of livestock grazing. We found that 2 metrics, percent live vegetation and bare ground, consistently reflected a seasonal effect of grazing. Litter cover also consistently reflected overall seasonal differences, but results often were not significant. Results for species richness suggested this metric may be most applicable when measured at the end of the grazing season. In contrast, we found that the wetland index values and percent cover of graminoids and forbs inconsistently reflected changes in vegetation due to grazing through the growing season. Future work should assess these attributes over several years to determine whether they are better able to discern multiyear trends than current status. By understanding which metrics change over the season and whether they change consistently among riparian areas, land managers can determine which metrics are suitable for short- and long-term monitoring of riparian plant communities. A better understanding of the metrics used to measure cattle grazing may help managers act to improve riparian areas while simultaneously providing ranchers options to graze these sensitive ecosystems.
Publication DateDecember, 2015
Citation InformationLaine, CM; Kettenring, KM; Roper, BB. 2015. An Assessment of Metrics to Measure Seasonal Variation in and Grazing Effects on Riparian Plant Communities. Western North American Naturalist 75(1):102-114. https://doi.org/10.3398/064.075.0111