Data Paper. Data Paper

File List Each file is ASCII text, comma delimited. No compression schemes were used in any file. MSH_SPECIES_PLOT_YEAR.csv is a species percent cover by plot by year matrix. File is 1743 lines, not including the header row. MSH_STRUCTURE_PLOT_YEAR.csv is a vegetation structure (richness, cover, H’, evenness, and mean frequency) by plot by year matrix. File is 1743 lines, not including the header row. MSH_SPECIES_DESCRIPTORS.csv provides systematic species information and details about species characteristics (family, species with authority, common name, synonymy and taxon comments, code used in notes and in species file, NLPSP code, succession status, higher taxon, life span duration, life form, growth form, degree of clonal growth, dispersal type, origin{native or exotic} and sites). File is 85 lines, not including the header row. MSH_PLOT_DESCRIPTORS.csv provides geographic location for each plot in the data base, including: Plot name, plot code, first and last year sampled, UTM easting, UTM northing, longitude, latitude, potential radiation, heat load, elevation, aspect, slope, and impact types. File is 92 lines, not including the header row. Description I established 92 permanent plots on Mount St. Helens starting in 1980 in order to document vegetation recovery from volcanic disturbances. I report data in 1743 records (plot × year), containing 85 species. These represent most common species found in non-forested habitats on Mount St. Helens. Richness, percent cover, diversity (<i>H'</i> and evenness), and species frequency of a plot are reported. Plots were sampled using 24 quadrats placed in the same location in each sample year by the same observer. Habitats sampled included those experiencing primary succession, secondary succession, and recovery from disturbance. These data have been used to test hypotheses concerning succession trajectories and patterns of species assembly. They also may be used to test models of succession, determine succession rates by several methods, and for exploring assembly processes and rules. Four files provide the data: (1) The matrix of species in each plot in each year; (2) The matrix of structural measures (e.g., richness) in each plot in each year; (3) taxonomic and life-history characteristics of species in the data set; and (4) geographic and landscape factors for each plot. These data are described in a metadata file, which includes numerous time-series images. <i>Key words: </i><i>primary succession; secondary succession; species assembly; species–time relationships; succession trajectories; vegetation dynamics; volcanoes</i>.