Vegetation development on permanently established grids, Mount St. Helens (1986–2010)

We established five grids consisting of 100-m2 plots on Mount St. Helens starting in 1986 in order to document vegetation establishment and dispersal after a major volcanic disturbance. These grids are contiguous, so they sample a compact area with limited habitat variation. We report data for these grids: Abraham Plains (400 plots, 7168 records, 4 hectares); Lahar 1 (175 plots, 1987 records, 1.75 hectares); Lahar 2 (317 plots, 3487 records, 3.17 hectares); Pumice Plain (200 plots, 4394 records, 2 hectares); and Willow Springs (1600 plots, 8351 records, 16 hectares). The grids contain 137 species. These species include most common species that are found in open habitats on Mount St. Helens, as well as many wetland species. Richness, total cover index, and diversity (H′, the Shannon-Wiener function) of a plot are reported for each sample year. Plot cover was estimated with cover indices that sacrifice precision for rapid assessment of large areas. Habitats were those experiencing primary succession on pyro...