Background Data Preparation for Spatially Explicit Potential Vegetation Modelling in the CLIMANATRES Project to Support Sustainable Ecological Restorations in the Face of Climate Change

Ecological restoration is gaining prominence in nature conservation, particularly under the European Union’s Nature Restoration Regulation, which emphasizes the need to integrate climate resilience into restoration planning. The CLIMANATRES project (Climate-proofing ecological restoration plans in the Middle and Lower Danube Region) addresses this demand by developing climate-resilient modeling tools across the Danube lowlands and adjacent mid-elevation mountains (<500 m a.s.l.). This study establishes a consistent climatic background variable set for potential natural vegetation (PNV) models that assess habitat survival under present and future climate conditions. We calculated bioclimatic variables based on the high-resolution (30 arc-sec, ≈1 km) CHELSA climate data for a reference period (1981–2010) and two future periods (2041–2070, 2071–2100) under two emission scenarios (SSP3-7.0, SSP5-8.5) and five global climate models. Nineteen bioclimatic variables were calculated following an ecologically refined protocol that fixes climate periods (e.g., wettest quarter) identified from the reference period to ensure comparability and ecological relevance under shiming seasonal patterns. The resulting high-resolution surfaces were integrated into the CLIMANATRES WebGIS platform to visualize spatial and temporal trends. This refined climatic dataset balances technical feasibility and ecological interpretability, providing a robust foundation for modeling vegetationclimate relationships and supporting climate-resilient ecological restoration planning across Middle and Lower Danube Region.