Plant silicon as a factor in Medusahead (Taeniatherum caput-medusae) invasion

Authors: SPACKMAN, C - New Mexico State University; Monaco, Thomas; Stonecipher, Clinton - Clint; VILLALBA, J - Utah State University

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2020
Publication Date: 7/14/2020
Citation: Spackman, C., Monaco, T.A., Stonecipher, C.A., Villalba, J.J. 2020. Plant silicon as a factor in Medusahead (Taeniatherum caput-medusae) invasion. Invasive Plant Science and Management. 13(3):143-154. https://doi.org/10.1017/inp.2020.20.
DOI: https://doi.org/10.1017/inp.2020.20

Interpretive Summary: Medusahead is one of the most problematic invasive grasses on rangelands in the western U.S. Many techniques have been used to control medusahead, but none have proven effective. Consequently, this article outlines a new interpretation of the weaknesses of current management techniques and introduces the need to place plant silica concentration as a central aspect of its ecology and management. Here, the authors present a new conceptual model and comprehensively explain the roles of plant silica in three fundamental processes: 1) plant fitness, 2) plant structure, and 3) chemical composition. Authors also outline key research needs to direct future studies.

Technical Abstract: Medusahead (Taeniatherum caput-medusae (L.) Nevski) is currently one of the most detrimental invasive annual grasses impacting the sustainability and function of rangeland in the western United States. Current control strategies often overlook the underlying causes of invasion, which is high tissue silicon (Si) concentrations. A comprehensive conceptual model that incorporates the role of high tissue concentrations of Si in medusahead facilitates invasion by directing impacting key plant characteristics (i.e., plant fitness, plant structure and chemical composition) while both directly and indirectly influencing ecological processes (i.e., plant productivity, litter accumulation, and herbivory) that promote a positive feedback cycle, reinforce medusahead dominance, and diminish native species coexistence. This model stimulates an ecologically-based understanding of the mechanisms underlying medusahead invasion and can be used as a framework to elucidate research needs and avenues for managers to interrupt fundamental aspects of the positive feedback cycle. Thus, the synthesis article first identifies knowledge gaps, then it provides a comprehensive synthesis of medusahead invasion and the self-reinforcing feedback model, and it finally suggests numerous essential research avenues and forges a path to developing more effective control strategies.