Grazing interactions: Cattle, goats, and fire in a changing landscape

Woody plant encroachment threatens rangeland productivity globally, yet traditional management approaches using fire, herbicides, or mechanical removal provide only temporary control. My work evaluates a management framework that combines pyric herbivory (interaction between fire and grazing) with mixed-species grazing to address woody and invasive plant encroachment in tallgrass prairie rangelands. I reviewed ecological processes impacting woody encroachment and examine pyric herbivory coupled with mixed-species grazing as an alternative management strategy. This review synthesizes evidence for how cattle and goats create complementary disturbance through different dietary preferences, potentially enhancing woody plant control beyond single-species systems. Next, I examined patch selection behavior of cattle and goats in a pyric herbivory system across 6 pastures. Using GPS collar data, I found both livestock species selected recently burned patches, with selection decreasing as time since fire increased. While cattle selection was strongly influenced by burn season, goat selection showed greater variability, suggesting complementary grazing patterns that could enhance landscape-scale management. We then tested treatment effectiveness using paired exclosures across the same pastures to compare fire-only, cattle-only pyric herbivory, and cattle with goats pyric herbivory on three target plant species: Rubus spp., Lespedeza cuneata, and Rhus spp. Fire-only treatments allowed target species height and vertical obstruction to increase 41-183% over three years. Cattle-only pyric herbivory partially suppressed regrowth, while adding goats reversed growth trends, reducing height up to 28% and vertical obstruction up to 40%. Finally, I evaluated community-level vegetation responses, finding that adding goats increased grass cover by 14% but did not reduce total woody cover. Instead, goat browsing restructured the woody community, which decreased palatable species while inadvertently favoring browse-resistant species. These findings demonstrate that integrating goats with cattle in pyric herbivory systems enhances forage production and provides targeted control of species woody species, though not broad-scale woody plant reduction. This research provides evidence-based guidance for managers implementing mixed-species grazing strategies in rangelands.