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The replacement of wild ungulate herbivores by domestic livestock in African savannas is composed of two interrelated phenomena: 1) loss or reduction in numbers of individual wildlife species or guilds, and 2) addition of livestock to the system. Yet very few studies have addressed the individual, combined, and potentially interactive effects of the presence and absence of wild versus domestic herbivore species on herbaceous plant communities within a single system. Additionally, there is little experimental evidence addressing the question of whether, and in which contexts, livestock might functionally "replace" native herbivore wildlife. The Kenya Long-term Exclosure Experiment (KLEE) has since 1995 manipulated access by different replicated combinations of mega-herbivores, meso-herbivore ungulate wildlife, and cattle in a wooded savanna ecosystem. Herbaceous vegetation was sampled 25 times between 1999 and 2013 in each of the eighteen 4 ha KLEE plots. We found evidence for additive effects of the resident community of wild ungulates (which included grazers, browsers and mixed feeders) and cattle (mostly grazers) on herbaceous community composition. Our results suggest that overall herbivory pressure, rather than complex interactions among different types of herbivores, drove the dominant trends in plant community dynamics. Differences between cattle and wild ungulate impacts on the herbaceous layer of this savanna ecosystem may be related more to the higher density of cattle than to differences related to species-specific, per-animal impacts. Additionally, although our results suggest considerable functional similarity between a suite of native wild herbivores (spanning different feeding guilds) and domestic livestock with respect to understory plant community composition, responses of individual plant species demonstrate that at the plant population level, impacts of a single livestock species are not functionally identical to those of a diverse group of native herbivores.