Response of bluebunch wheatgrass to invasion: Differences in competitive ability among invader‐experienced and invader‐naïve populations

Abstract

Invasive species may alter selective pressures on native plant populations. Although there is some evidence that competition with invasive plants may lead to differences in competitive ability between populations that have experienced invasion and those that have not, previous results have varied among species but also among populations of the same species. We conducted a glasshouse experiment to determine whether there was variation in traits or in ability to tolerate or suppress an invasive species among populations of a common native grass that had different histories of exposure to competition from an invasive species. Specifically, we grew seeds of a native grass (Pseudoroegneria spicata) collected from 14 wild populations (six from invaded populations and eight from uninvaded populations) and a cultivar (Anatone) alone or in competition with the invasive aster (Centaurea stoebe) and measured traits of both species during and at the end of a 100‐day growing period. Pseudoroegneria spicata seedlings from invader‐experienced populations had more leaves than invader‐naïve populations, and juvenile plants from experienced populations were less affected by competition with C. stoebe than were plants from naïve populations. There were significant differences in traits among populations at the seedling and juvenile life stages, and at both life stages variation among populations was greater than variation among experience types. The most predictive traits of P. spicata tolerance to competition were number of leaves (seedling and juvenile stage) and total and root biomass (juvenile only). No traits significantly predicted suppression of C. stoebe. There was not a significant relationship between a population's suppression of C. stoebe and its tolerance of competition. Our results suggest that, in P. spicata, invasion selects for larger plants and traits that can influence tolerance of competition. If land managers are interested in identifying highly competitive seed sources for revegetation in invaded areas, both population and invader experience type should be considered. As tolerance and suppression do not appear to be related in P. spicata, seed source selection should be driven by the element of competitive ability (either tolerance or suppression) that is most important to project goals. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13090/suppinfo is available for this article.

Native plant species show evolutionary responses to invasion by Parthenium hysterophorus in an African savanna

“…competitive response of P . hysterophorus ) ( sensu Gibson et al ., 2018). In the experiment, invader‐experienced and conspecific naïve individuals of the seven native species were grown in 2‐l pots individually and in pairwise competition with P .…”

“…competitive effects of P. hysterophorus) and the degree to which P. hysterophorus tolerated the impact of native plants (i.e. competitive response of P. hysterophorus) (sensu Gibson et al, 2018). In the experiment, invader-experienced and conspecific na€ ıve individuals of the seven native species were grown in 2-l pots individually and in pairwise competition with P. hysterophorus, and under different scenarios of soil nutrient enrichment and moisture availability.…”

Getting to the root of restoration: considering root traits for improved restoration outcomes under drought and competition

“…Goldberg & Fleetwood 1987), uncorrelated (e.g. Gibson et al 2018), and negative (e.g. Wang et al 2010).…”

Early Plant Development in Intermediate Wheatgrass

“…Competition during emergence and early growth will be important for success of a crop species [56]. In Pseudoroegneria spicata, increased leaf number achieved in the juvenile stage (25 days after emergence) indicated greater competitiveness with Centaurea stoebe [57]. Early appearance in stands enhances an individual's ability to grow [58].…”