Autecology of Erythronium grandiflorum in western Canada

Habitat requirements of the yellow glacier lily, Erythronium grandiflorum P ursh, were studied at 38 sites in southern British Columbia and southwester n Alberta. At each site we recorded densities of E. grandiflorum growth sta ges from seedling to flowering, environmental characteristics of the site, and percent cover of associated plant species. We carried out detrended cor respondence analysis (DCA) of the sites based on cover of associated specie s, and examined rank correlations between site environmental variables and site ordination scores. Variation among sites was related primarily to elev ation and the presence of deciduous vs. coniferous trees. All growth stages of E. grandiflorum were less abundant in coniferous forests than in open a reas or sites with deciduous trees, suggesting that evergreen canopies rest rict the species on many sites where it could otherwise grow. Although E. g randiflorum populations were most commonly found in subalpine meadows, they flowered more abundantly in low-elevation populations. Recruitment was fre quent, with seedlings occurring at many sites; we also showed that detached bulb segments can give rise to new ramets. The present widespread distribu tion of E. grandiflorum may derive from a post-glacial period with extensiv e meadow habitat that was favourable for rapid spread.