Characterization of ‘safe sites’ for pioneers in primary succession on recently deglaciated terrain

1 We characterized safe sites for individuals of five early colonizers (Abies lasiocarpa, Juncus drummondii, J. mertensianus, Saxifraga ferruginea, S. tolmiei) that had survived at least one growing season on the recently deglaciated forefront of the Lyman Glacier in the North Cascade Mountains, Washington, USA. 2 Sites with concave surfaces, coarse surface substrate and in the vicinity of large rocks were more likely to be colonized by pioneering plant species. 3 We speculate that the distribution of plants is determined by the presence of sites that facilitate seed trapping and protect seeds and seedlings from desiccation. 4 The data identify the abiotic factors that determine initial recruitment and spatial distribution of plants. Such controls precede biotic interactions in this primary successional sere.