Effect of Traffic by Lightweight Forest Machinery on the Growth of Young Picea abies Trees
The effect of traffic by lightweight forest machinery (5-9 Mg) on soil properties and tree growth was assessed in young stands of Picea abies (L.) Karst. Seven sites in the central and southern part of Sweden were monitored for 3 yrs after cleaning operations had been carried out in them. Leader length and diameter of the young trees as well as rut depth and cone penetrometer resistance were measured. The machines made 1-2-cm-deep ruts which had decreased in depth by 40% after 1 yr. Cone penetrometer resistance was slightly increased in the ruts, indicating that the soils were subjected to some degree of traffic-induced compaction. The growth of the trees (n=1073) measured did not differ statistically significant between trees at a distance of 0-1 m from the rut and those > 2 m from the rut. In conclusion, traffic by lightweight machinery in young forest stands can occur without affecting tree growth.