The source population dictates invasion and invasion impact in the Neotyphodium coenophialum - Festuca arundinacea model system

Background/Question/Methods

The presence of the asexual fungal endophyte Neotyphodium coenophialum in Festuca arundinacea (Tall fescue) may affect the structure and function of communities containing infected hosts.  However, it is unclear if the effects of endophyte infection are consistent across populations (cultivars) of F. arundinacea, as our understanding of the effects of endophyte infection has largely been derived from studies of one common cultivar.  In 2007, an experimental field study was established to address the questions 1) do communities planted with endophyte infected (E+) and endophyte free (E-) F. arundinacea cultivars differ in structure and function, and 2) are responses among communities established with variously derived E+ and E- cultivars consistent?  We seeded 4m² plots in an old-field community with E+ and E- cultivars to test the hypotheses that communities seeded with E+ cultivars will contain more F. arundinacea, be less diverse, and use resources differently than communities seeded with E- cultivars.

Results/Conclusions

After four growing seasons, plots seeded with E+ forage and turf cultivars were more diverse, contained higher abundances of F. arundinacea, and contained lower abundances of additional non-native cool-season grasses than plots seeded with comparable E- cultivars.  Productivity (NDVI) and nitrogen mineralization also variously differed among plots planted with E+ and E- cultivars at various points in the growing season.  Our results suggest that communities formed with different types of cultivars (endophyte status and turf versus forage application) will have different responses, but responses should be consistent among cultivars of the same type.  Thus, findings from studies of a single cultivar are likely extendable to other cultivars of the same endophyte status and application.  Additional evidence suggests that it is likely that the production of infected cultivars in this system resulted in selection for additional traits that are unrelated to infection.  Future studies will be aimed at investigating how differences in species composition between E+ and E- plots arose in our system and determining the extent to which effects were caused by endophyte status of the host versus effects of selection on host traits unrelated to endophyte infection.