Baseline riparian forest and aquatic vegetation dataset from the Danube right bank near Draž (Croatia) to support before–after monitoring of side-arm reconnection (2024–2025)

This dataset provides a baseline record of riparian forest and aquatic vegetation collected along the right bank of the Danube River near the village of Draž (Croatia), prior to planned hydro-technical measures aimed at reconnecting a cut-off side arm to the main channel. Riparian forest vegetation was surveyed on 20 May 2024 using three 10 × 10 m plots per site, whereas aquatic vegetation was surveyed on 30 July 2025 using three 10 m belt transects per site. Species cover was estimated using the Domin cover-abundance scale in forest habitats and a five-level ordinal cover scale in aquatic habitats. The dataset consists of three linked CSV tables (event, occurrence and measurementOrFact) following Darwin Core principles. It contains sampling events, species occurrences, vegetation cover estimates and associated environmental variables. The dataset represents the baseline ("before") component of the ecological monitoring programme established within the Horizon Europe project DANUBE4all and is intended to support future assessments of vegetation responses following side-arm reconnection. This dataset is described in the following data paper: Vukov D, Žunić D, Prodanović N, Sabadoš V (2026) Baseline riparian forest and aquatic macrophyte vegetation dataset from the Danube right bank near Draž (Croatia), to support before-after monitoring of side-arm reconnection (2024-2025). Biodiversity Data Journal 14: e190669. https://doi.org/10.3897/BDJ.14.e190669