Ecological Invasion, Impact, and Management of Johnson Grass [<em>Sorghum halepense</em> (L.) Pers.] for Sustainable Livestock Production: A Systematic Review

Sorghum halepense (Johnsongrass) is widely recognised as one of the most aggressive invasive perennial grasses affecting agricultural and rangeland ecosystems worldwide. Its rapid spread, ecological adaptability, and dual role as both a potential forage resource and a toxic risk to livestock present complex challenges for sustainable livestock production. Despite extensive research on its ecology and management, existing knowledge remains fragmented across multiple disciplines, limiting the development of integrated control strategies. This systematic review synthesises existing scientific evidence on the ecological invasion dynamics, origin and distribution patterns, biodiversity impacts, livestock-related risks, and management strategies associated with S. halepense, intending to inform sustainable livestock production systems. A systematic literature review approach was employed to identify and evaluate peer-reviewed and grey literature. Relevant studies were retrieved from major scientific databases, including Google Scholar, PubMed, and ResearchGate, using predefined search terms related to S. halepense, invasion ecology, livestock toxicity, and weed management. Articles were screened based on relevance, methodological quality, and thematic alignment with the objectives of the review. The findings indicate that S. halepense has successfully invaded diverse agro-ecological regions due to its hybrid origin, polyploid genome structure, prolific seed production, and extensive rhizome system. The species significantly alters plant community composition, reduces biodiversity, and competes with crops and native forage species. Although it may provide forage under certain conditions, its accumulation of cyanogenic compounds and nitrates poses serious poisoning risks to grazing livestock. Current control strategies, including mechanical removal, cultural practices, herbicide application, and prescribed burning, vary in effectiveness and are often limited by ecological constraints, cost, and the increasing emergence of herbicide resistance. The review highlights the need for integrated, ecosystem-based management strategies that balance invasive weed control with sustainable forage production. Future research should prioritise climate-responsive management approaches, improved understanding of invasion ecology, and the development of cost-effective control measures suitable for livestock production systems. A multidisciplinary framework integrating weed science, rangeland ecology, and animal health will be critical for mitigating the ecological and economic impacts of S. halepense in invaded landscapes.