Abstract Heavy forwarders can cause rutting and compaction when operating on wet or soft soils, limiting harvest opportunities in boreal forests to periods with frozen soil. This study applies a mechanistic soil trafficability model, integrating forwarder specifications, soil mechanical properties, and long-term climate data, to evaluate operational feasibility under Finnish conditions. Monte Carlo simulations were used to examine the sensitivity of trafficability predictions to variability in soil mechanical parameters. Results show that coarse mineral soils generally sustain traffic without frost, whereas fine-textured soils and peatlands require frozen conditions. Model-derived threshold frost depths ranged from 0.02 m in clay to over 0.30 m in mud, representing minimum values required for trafficability under idealized single-pass conditions. Interannual variability significantly influenced operational windows. Friction angle dominated trafficability variability in mineral soils, while cohesion was critical in clay and peat soils. Comparisons with the Finnish Forest Centre’s operational map revealed general agreement, while the mechanistic approach provides insight by quantifying parameter sensitivity and capturing seasonal dynamics. The results are based on model simulations and no independent field validation is included. These findings provide a framework for understanding soil trafficability constraints and support planning of winter harvesting operations under variable and changing climatic conditions.
Mattila et al. (Sat,) studied this question.