Fig. 1. Description of the location of gas flux measurement on the skid trail and on the undisturbed forest soil: 1 (control) = uncompacted soil, 2 (US_B) = untrafficked soil bordering one side of the trafficked soil, 3 (TS_B) = trafficked soil bordering one side on the untrafficked soil, 4 (TS_M) = middle of the trafficked soil, 5 (US_M) = untrafficked soil between the two wheel tracks.