Data Paper. Data Paper

File List GRID_SPECIES_DESCRIPTORS_ALL.csv -- includes all species encountered on these grids, supplemented by characterizations of their ecological traits. There are 137 lines of data, not including the header row, with each record providing data for a species encountered on one or more grids. GRID_DESCRIPTORS.csv -- provides geographic and ecological data for the 5 grids. There are 5 lines, not including the header row. ABRAHAM_SPECIES_PLOT_YEAR.csv -- is a matrix of species cover index by plot and by year (1988 to 2010) for the Abraham Plain grid. It has 7167 lines, not including the header row. LAHAR_1_SPECIES_PLOT_YEAR.csv -- is a matrix of species cover index by plot and by year (1987 to 2008) for the Lahar 1 grid. It has 1987 lines, not including the header row. LAHAR_2_SPECIES_PLOT_YEAR.csv -- is a matrix of species cover index by plot and by year (1987 to 2004) for the Lahar 2 grid. It has 3487 lines, not including the header row. PUMICE_SPECIES_PLOT_YEAR.csv -- is a matrix of species cover index by plot and by year (1989 to 2010) for the Pumice Plain grid. It has 4394 lines, not including the header row. WILLOW_SPRINGS_SPECIES_PLOT_YEAR.csv -- is a matrix of species cover index by plot and by year (1986 to 2010) for the Willow Springs grid. It has 8346 lines, not including the header row. ABRAHAM_STRUCTURE_PLOT_YEAR.csv -- is a matrix of richness, cover index and <i>H</i>' by plot and by year (1988 to 2010) for the Abraham Plain grid. It has 7167 lines, not including the header row. LAHAR_1_STRUCTURE_PLOT_YEAR.csv -- is a matrix of richness, cover index, and <i>H</i>' by plot and by year (1987 to 2008) for the Lahar 1 grid. It has 1987 lines, not including the header row. LAHAR_2_STRUCTURE_PLOT_YEAR.csv -- is a matrix of richness, cover index, and <i>H</i>' by plot and by year (1987 to 2004) for the Lahar 2 grid. It has 3487 lines, not including the header row. PUMICE_STRUCTURE_PLOT_YEAR.csv -- is a matrix of richness, cover index, and <i>H</i>' by plot and by year (1989 to 2010) for the Pumice Plain grid. It has 4394 lines, not including the header row. WILLOW_SPRINGS_STRUCTURE_PLOT_YEAR.csv -- is a matrix of richness, cover index, and <i>H</i>' by plot and by year (1986 to 2010) for the Willow Springs grid. It has 8346 lines, not including the header row. Description 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 (<i>H</i>', 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 pyroclastic, lahar, and pumice surfaces. These data have been used to test hypotheses about succession trajectories, patterns of species assembly, and developing environmental control of species composition. They may be used to test models of succession, determine succession rates, and explore assembly rules. <i>Key words: primary succession; species assembly; species–time relationships; succession trajectories; vegetation dynamics; volcanoes</i>.