From Theoretical Wood Availability to Mobilizable Bioenergy: A Constraint-Cascade Assessment on Monte Isola, Italy

Forest bioenergy is often inferred from standing stock or biological growth, although only part of that resource becomes usable fuel after accounting for silvicultural, spatial, and operational constraints. We quantified this reduction on Monte Isola, a forested island in northern Italy, defining it as scenario-based technical potential rather than an estimate of immediately marketable supply. We combined a forest inventory of 14 plots selected by stratified random sampling (479 trees) with 58 quality-controlled increment-core observations sampled independently of the plots. These data supported a 15-year growth projection and a GIS analysis of accessibility. The baseline harvesting system was conventional ground-based tractor/skidder–winch extraction. Forest was classified as technically accessible if it lay within 100 m of usable roads or tracks and had a terrain slope of ≤40%. Cable-based extraction was excluded because no data were available on local cable-yarding deployment, anchor and landing configurations, or the feasibility of individual cable lines. Projected gross increment was 34,736 m3 over 15 years. After accounting for mortality, slope-constrained accessibility, 60% operational recovery, and 10% processing losses, 2901 m3 remained as processed wood-fuel equivalent, or 193 m3 year−1. The resulting baseline was 0.58 GWh year−1 or 49.6 TEP year−1. Bootstrapping with 5000 replicates propagated sampling uncertainty in cores and plots, yielding a 95% interval of 39.6–62.8 TEP year−1. Varying the ground-based slope limit from 30% to 50% produced a separate scenario range of 18.9–91.6 TEP year−1. The baseline theoretical energy equivalent represents 10.0% of a project-specific benchmark for residential diesel and LPG use. This benchmark was derived from 2015–2020 building energy records and 2020 housing and population assumptions, rather than contemporary fuel sales. Excluding the oak-rich forest type reduced the theoretical energy equivalent by 5.9%. This reduction is specific to the scenario and does not quantify a general penalty for cascading use, greenhouse gas mitigation, or ecological sustainability. Terrain-constrained accessibility and operational recovery dominated scenario sensitivity. These results provide a transparent basis for screening local forest bioenergy options while treating statistical uncertainty, operational scenarios, and ecological sustainability as separate questions.