The effect of endophyte presence on Schedonorus arundinaceus (tall fescue) establishment varies with grassland community structure

Abstract

The endophyte Neotyphodium coenophialum in Schedonorus arundinaceus (tall fescue) may alter host interactions with specific resident species or shift the host's niche. These effects can be quantified by assessing tall fescue responses to, and effects on, the variation among resident species (selection) and resident species interactions (complementarity). To determine how N. coenophialum affects tall fescue, grassland microcosms containing 16 transplants of two, four, or eight resident species were seeded with endophyte-infected (E+) or endophyte-free (E-) Kentucky-31 (KY-31) tall fescue. All resident species were also grown in monoculture. Aboveground biomass was harvested 9 weeks after tall fescue was added (18 weeks' total growth). At harvest, more E+ than E- individuals were present and they represented a larger portion of the aboveground biomass across richness treatments, despite similar germination in concurrent trials. Tall fescue individuals were larger in microcosms dominated by more productive resident species (greater selection). In contrast, fewer E-, but not E+, individuals were present in microcosms with more facilitative interactions among the resident species (greater complementarity). E- and E+ tall fescue also affected resident species differently. High-richness E+ microcosms were more diverse and less dominated by productive species (lower selection) than E- microcosms. Thus, E+ KY-31 may more readily establish in, and affect, species-rich, functionally diverse communities as a result of niche shifts during establishment and negative effects on specific resident species. Although results need to be further tested under field conditions, it appears that endophyte presence may only facilitate KY-31 invasion into a limited suite of community types.

Effects of theEpichloëfungal endophyte symbiosis withSchedonorus pratensison host grass invasiveness

“…Similar to the results of Yurkonis et al (2012Yurkonis et al ( , 2014a, effects of Schedonorus species on plant community composition depended more on the particular cultivar than on the species or endophyte status, as indicated by our multivariate analysis. Cultivars could not be grouped based on species or endophyte effects on plant community composition.…”

“…There is corroborating evidence that this was also the case for five forage and five turf S. arundinaceus cultivars at the same site (Yurkonis et al 2012). The success of Schedonorus invasion may depend on interactions with the particular competing plant community (Saikkonen et al 2000;Takai et al 2010;Yurkonis et al 2012Yurkonis et al , 2014a. Given that some previous S. arundinaceus studies have been performed in communities that were originally dominated by S. arundinaceus (e.g., Clay and Holah 1999;Spyreas et al 2001), legacy effects might explain its greater abundance at those sites than at our site, regardless of endophyte status.…”

“…2010; Yurkonis et al. 2012, 2014a,b). Given that some previous S. arundinaceus studies have been performed in communities that were originally dominated by S. arundinaceus (e.g., Clay and Holah 1999; Spyreas et al.…”

“…Because of the advantages that endophyte-infected individuals seem to have relative to uninfected conspecifics, one research question that has garnered significant interest is whether endophyte infection enhances the invasiveness of the host in a community context. Many glasshouse experiments have examined whether endophyte infection increases host competitive ability, and some have specifically examined broader plant community effects (e.g., Rudgers et al 2005;Yurkonis et al 2014a). Field experiments have been rarer.…”