Mapping and Structural Assessment of Woody Vegetation in Bavaria using Digital Elevation Models and multisource Geodata

Kurzfassung

The recent provision of high-resolution stereo aerial imagery and digital surface models through Bavaria's open geodata portal has created new opportunities for mapping woody vegetation independent of land use and without the need of machine learning models. This study exploits these data to produce a wall-to-wall Woody Vegetation Height Model (WVHM) for the entire State of Bavaria at 1 m resolution. Structural information from an image-based normalised digital surface model, derived from official elevation products, is combined with spectral indices and ancillary data to build successive masks that iteratively isolate woody vegetation in a transparent, reproducible workflow. Unlike forest-focused inventories and the majority of canopy height datasets existing for Bavaria, the WVHM also captures trees outside forests (TOF), which conventional monitoring largely overlooks. The WVHM maps 25,174 km² of woody vegetation, covering 35.68 % of the state's area. TOF contributes 9.05 % of all mapped woody vegetation, challenging the assumption that non-forest woody vegetation is marginal relative to forest systems. Forest reaches a median canopy height of about 20 m, peaking near 25 m, indicative of mature, managed stands, whereas TOF, dominated by hedgerows, riparian strips and orchards, has a median of about 8 m and a 95th percentile of 21. m. Across multiple ecological and administrative stratifications, the two classes show consistent contrasts that point to distinct management regimes and complementary landscape positions. By capturing forest vegetation together with the currently overlooked vegetation outside forests, the WVHM addresses a persistent gap in carbon accounting, biodiversity assessment and vegetation monitoring. Its open inputs, transparent rule-based design and regular update cycle make it a repeatable basis for structural woody vegetation assessment, transferable across Germany through nationwide AdV-standard aerial data.