The enhancement of invasion ability of an annual grass by its fungal endophyte depends on recipient community structure

CASAS, C; GUNDEL, PE; SEMMARTIN, M.; SCHNYDER, H; OMACINI, M.

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2016

1387-3547

Most terrestrial plants establish symbiotic and mutualisticrelationships with diverse microorganisms that influence their performanceunder stressful conditions. While soil microbial mutualisms have been studiedextensively, here we investigated how aerial mutualisms involving invasivespecies may affect the recipient community?s structure. We hypothesized that the endophyte Epichloë occultants enhances theability of Lolium multiflorum toestablish and colonize, but that success would depend on the structure andinvasion resistance of the recipient grassland community. Seeds of L. multiflorum with high (E+) and low(E-) endophyte incidence were sown in plots located in grasslands with orwithout grazing history. Relative cover of L.multiflorum and floristic groups was determined during the growing season.Whereas we did not detect any endophyte effect in sites with grazing history, L. multiflorum cover was63% in E+ and 27% in E- plots without grazing history. In the latter, thecover of warm-season grasses decreased by 1.9% in spring and 1.6% in summer,and that of cool-season grasses decreased by 3.7% in spring for each percent increase of L. multiflorum cover. Path analysis andposterior modelling predicted that the impact of the endophyte on L. multiflorum cover was greater thanthat of seed addition when resident L.multiflorum cover was about 20% and this effect decreased to near 0.3 when L. multiflorum cover was about 80%. Ourresults suggest that the endophyte may boost the invasion ability of L. multiflorum particularly in naturalgrassland without grazing history with potentially critical consequences for communitystructure and dynamics.