This table provides presence/absence (binary occurrence) data for adult spiders (Arachnida: Araneae) at the 768 sampling points of the HIGH-PBS dataset, across 29 high-elevation sites in the Italian Alps and Apennines (1,875–3,120 m a.s.l.), surveyed between 2010 and 2023. The data were derived from the activity density records obtained by pitfall trapping (see spider_abundance.tab in the same submission for full methodology): each species column contains a binary value, with 1 = at least one adult individual recorded at that sampling point and 0 = species not recorded. The table is provided alongside the activity density version to offer a conservative, directly comparable occurrence measure that accommodates analytical approaches (e.g. occupancy models, beta-diversity metrics, community composition analyses) for which quantitative capture rates are not required or not appropriate. It also allows users to include sites where only presence/absence data could be derived. The table covers 128 Araneae species identified to species level; identification followed Nentwig et al. (Spiders of Europe) and nomenclature follows the World Spider Catalog. Each row is identified by three columns: Event label (unique sampling point identifier, primary key shared with the other five tables of the dataset), Code Landform (CS, DG, F1, F2, RGa, RGr, SF, SS) and Code Area (29 site codes). Voucher specimens are preserved in ca. 70% ethanol at the MUSE - Science Museum of Trento (Italy) and at the Museo Civico di Scienze Naturali "E. Caffi" of Bergamo (Italy).

Spider (Araneae) presence/absence data per pitfall trap, containing: * Event label: sampling point identifier (Code: Multiple naming conventions are used, reflecting different sampling campaigns: format 1 (395 points): Site.Landform.Plot.Point (e.g., Agl.CS.1.a); format 2 (275 points): SITE##X (e.g., AGO32B, CLA31A, PEI12A); format 3 (30 points): SITE##.X (e.g., LAZ01.A); format 4 (24 points): U##.X (e.g., U05.A) — Val d'Ultimo site; format 5 (other): site-specific codes (e.g., FRA-FRO11A, SORC3.1A); two labels end in .vista (visual surveys on previously sampled plots),* Latitude, longitude, elevation, location of sampling event, * Code Area: site code, * Code Landform: landform type, * Year of sampling, * Species columns (128 species) as presence/absence: binary values (1 = species present, 0 = species absent at that sampling point).