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

CASAS, C. ; GUNDEL, P.E.; SEMMARTIN, M.; HANS, S.; OMACINI, M.

BIOLOGICAL INVASIONS

SPRINGER

Lugar: Berlin; Año: 2016 vol. 18 p. 1853 - 1865

1387-3547

Most terrestrial plants establishsymbiotic associations with microorganisms that enable them to overcome abioticor biotic filters in ecosystems. Here we investigated how aerial mutualismsinvolving invasive species may affect the recipient community?s structure. Wehypothesized that the endophyte Epichloe occultans enhances the ability ofLolium multiflorum to establish and colonize, but that success would depend onthe structure and invasion resistance of the recipient grassland community.Seeds of L. multiflorum with high (E+) and low (E-) endophyte incidence weresown in plots located in grasslands with or without recent grazing history.Relative cover of L. multiflorum and floristic groups was determined during thegrowing season. Whereas we did not detect any endophyte effect in sites withgrazing history, L. multiflorum cover was 63 % in E+ and 27 % in E- plots insites without grazing history. As cover of L. multiflorum increased in thesesites, the cover of warm- and cool-season grasses decreased in spring, withthat of warm-season grasses continuing to decrease in summer. These decreasescorresponded to 1.9, 3.7 and 1.6 %, for every % increase of L. multiflorumcover. Path analysis and posterior modelling predicted a greater impact of theendophyte on L. multiflorum cover than of seed addition when resident L.multiflorum cover was < 20 %. This effect decreased asymptotically as L.multiflorum cover increased beyond 20 %. Our results suggest that the endophytemay boost the invasion ability of L. multiflorum particularly in naturalgrassland without grazing history with potential longer-term consequences forcommunity structure and dynamics.