Fig. 2

Field soil disturbance classification grid. Rut depth is measured below the original soil surface and corresponds to the deepest soil depression in the skid trail at the measurement’s location. For each criterion the score is determined according to rut depth, soil structure and the apparition depth of redoximorphic features. The sum of scores yields the degradation class of the skid trail: low, moderate and severe degradation class correspond to a sum of scores between 1 and 3, between 4 and 6 and between 7 and 11, respectively