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In arid rangelands, riparian areas are important components of ranching operations that also provide critical ecosystem services, including: habitat for fish and wildlife, increased landscape biodiversity, and regulation of the fate and transport of nutrients and pathogens. Many of these ecosystem services are mediated by vegetation composition and structure. In Mediterranean California, rangeland riparian sites likely behave in a non-equilibrium manner, where external abiotic factors shape vegetation composition and structure at multiple scales. Despite this, livestock are often cited as a major cause of rangeland riparian degradation. We monitored vegetation change along 5 creeks at Tejon Ranch in southern California, and found that livestock impacted vegetation in unexpected ways. Over two years, moderate cattle activity decreased cover of upland plants, exotic plants, forbs and grasses. Cover of wetland and native plants were unaffected by cattle, however bare ground significantly increased when cattle were present. There was also a near-significant increase in woody plant seedling abundance on grazed plots. Notwithstanding these effects on plant functional groups, a classification-based analysis of vegetation showed that cattle grazing had little effect on plant community composition. The results suggest that understanding the effects of cattle on riparian vegetation depends not only on the spatial and temporal scales of the investigation, but also on the way the vegetation response is framed.