This dataset contains the original data used in the article: Klinkovská K., Kučerová A., Pustková Š., Rohel J., Slachová K., Sobotka V., Szokala D., Danihelka J., Kočí M., Šmerdová E. & Chytrý M. (2023) Subalpine vegetation changes in the Eastern Sudetes (1973–2021): effects of abandonment, conservation management and avalanches. Applied Vegetation Science, 26, e12711. https://doi.org/10.1111/avsc.12711 The data contain plant species composition from vegetation plots repeatedly surveyed in the Hrubý Jeseník Mountains (Eastern Sudetes, Czech Republic). Vegetation plots surveyed by Leoš Bureš and Zuzana Burešová in 1973–1978 were resurveyed in 2004–2010 by Martin Kočí and Leo Bureš and resurveyed again in 2021 by the authors of this dataset. Several new plots were also surveyed in 2004–2010 and resurveyed in 2021. In the 1970s, plot locations were related to patches of a detailed vegetation map. In the 2000s, plot locations were measured using GPS with an uncertainty of less than 10 m. In 2021, plots were localized using differential GPS with ~5 cm accuracy (Topcon HiPer SR with Getac PS336 Data Collector) in each corner of the plot. These coordinates are stored in the fields Longitude, Longitude2, Longitude3, Longitude4, Latitude, Latitude2, Latitude3 and Latitude4 in the dataset. The dataset contains records of 148 vegetation plots, of which 66 were sampled three times (1970s, 2000s, 2021) and 82 were sampled twice (2000s, 2021), i.e. 362 vegetation-plot records in total. Their locations are shown at https://arcg.is/0uSrz9. Plot size and shape varied by vegetation type. Repeated sampling always used the same plot size as the previous sampling. Most plots were squares of 100 m2 in woodlands and 16 m2 in grasslands or rectangles of 10 m2 in springs. All species of vascular plants were recorded in each plot, and their cover was estimated using the nine-grade Braun-Blanquet scale (Westhoff & van der Maarel, 1978). Bryophytes and lichens were recorded in only some plots, focusing on the dominant species. In 2021, soil samples were collected from the mineral soil horizon at 5–10 cm depth from four places within each plot. We mixed these samples for each plot and measured the soil pH and electrical conductivity of a mixed sample in a soil-water suspension (weight ratio 1:2.5) using the HQ40D digital multimeter. These data are found in the fields Soil_ph and Conduct. Plots were divided into managed and unmanaged based on the overlay of plot coordinates with GIS layers indicating the areas managed for conservation purposes in the last ten years provided by the Administration of the Landscape Protected Area Jeseníky (field Mown). In addition, plots were divided into affected and unaffected by the 2019 avalanche based on the positions of damaged trees observed in the field (field Avalanch). The structure of header data follows the structure of the ReSurveyEurope Database (http://euroveg.org/eva-database-re-survey-europe). In addition, the vegetation type of each plot record in the 1970s, 2000s and 2021 is given in the fields Class_2021, Class_2000 and Class_1970, respectively The data on species composition and environmental variables are provided in two formats: Turboveg 2 database (see https://www.synbiosys.alterra.nl/turboveg/) – file TurbovegDbBackup_Jeseniky_resurvey.zip. To use this dataset in Turboveg, the database dictionary (TurbovegDdBackup_Default dictionary.zip) and species list (TurbovegSlBackup_Czechia_slovakia_2015.zip) have to be installed. Two TXT files with columns separated by tabs: Jeseniky_resurvey_species.txt contains the percentage covers of plant species in plots. Plant nomenclature harmonized according to Kaplan et al. (2019). Bryophytes, vernal species Anemone nemorosa and Cardamine pratensis, hybrids and species that could not be accurately identified were excluded. Woody species occurring in different layers were merged within each plot. Jeseniky_resurvey_head.txt includes information about the number of species in each plot (spe.nr), the number and proportion of threatened species (IUCN categories CR, EN, VU, columns end.nr and perc.end) and unweighted means of Ellenberg-type indicator values for light (Light_IV), temperature (Temp_IV), moisture (Moist_IV), soil reaction (React_IV) and nutrients (Nutr_IV) used to test changes in these variables through time. These data are also stored in the Czech National Phytosociological Database (Chytrý & Rafajová 2003; https://botzool.cz/vegsci/phytosociologicalDb) and the ReSurveyEurope database (http://euroveg.org/eva-database-re-survey-europe).

K. Klinkovská, A. Kučerová, Š. Pustková, J. Rohel, K. Slachová, V. Sobotka and D. Szokala are joint first authors of this dataset.