Langenheim Plant Species Data (1953) and Associated Resurvey Datasets (2014), Gunnison Basin, Colorado, USA

Quantitative plant abundance data were collected from the same 121 sites at two time periods separated by 65 years (1948-1952 and 2012-2014) in the Colorado Rocky Mountains to examine changes in plant community composition. The sites range in elevation from 2600m to 4100m. Approximately 30 sites were sampled from each of four habitat types: sagebrush (2528-3119m, n=27 sites), spruce-fir forest understory (3001-3520m, n=31 sites) , upland herb = montane meadow (3124-3850m, n=30 sites), and alpine (3549-4013m, n=33 sites). The earlier data set was collected by Jean H. Langenheim (1953, 1962) and consisted of counts of species occurrences along approximately 100m paced transects, noting species touching her boot tip every pace (n=100 sampled points per site). The later data set was collected by Stephanie D. Zorio (2015, 2016) consisting of counts of species occurrences every 1m along 300m transects (n=300 sampled points per site). The sites resurveyed by Zorio (2015, Zorio et al. 2016) were placed as close as possible to the original sites based on the written descriptions of Langenheim, but are only approximate. The GPS coordinates given for the resurveyed sites are the centerpoint of 2 perpendicular 150m transects, one across the slope and the other perpendicular to the slope. GPS coordinates for alpine sites along narrow ridges are the start and end points of three 100m transects along the ridge. Georeferenced localities and environmental site data are presented in Table 2: Lang Zorio Env Site Data. Langenheim’s original data were extracted from tables in her thesis (Langenheim 1953). These data omitted species that occurred in fewer than 14% of sites of a given habitat type (constancy). Species that occurred at very low frequencies (<1% per site) were only denoted as an x in the tables. Zorio converted these to frequencies of 0.5 for quantitative comparative purposes. This data set contains 157 species from 27 families across all sites and habitats. Species in seve