Get reliable rangeland science

In the western U.S., bottlebrush squirreltail (Elymus elymoides) is a frequent component of native seed mixes used to revegetate disturbed rangelands that are commonly at risk of invasion by cheatgrass (Bromus tectorum). Phenotypic variability among squirreltail populations has been documented, yet little is known about how these population-level differences influence the outcome of competitive interactions between squirreltail and cheatgrass. Through a common garden greenhouse experiment, we measured variation among 19 populations of E. elymoides in their tolerance of B. tectorum competition using a standardized, biomass-based index. Preliminary analyses indicate that subspecies identity is significantly related to competition tolerance (p = .003), but within a subspecies, there is marginal variation among populations in their tolerance of competition. We also explore the relationship of competitive tolerance to a suite of squirreltail growth traits, including days to germination, root:shoot ratio, specific leaf area, specific root length, and leaf number. The aim of this research is to clarify the range and drivers of competitive ability within the E. elymoides species. Outcomes may aid future development of ecologically successful native plant materials for rangeland reseeding efforts and the identification of populations that may contain traits of conservation concern.