Surface-bearing pressure in newer logging skid trails compared to the 40+ -year-old trails was approximately 60% greater as measured by a cone penetrometer. Surface soil compaction from tractor skidding may last 40 years or more, as evidenced by the fact that skid trails of that age were 20% more resistant to the penetrometer than areas adjacent to trails. No relationship was found between dry-bulk density (measured with a balloon apparatus) and surface-bearing pressure.
Vora, Robin S.
"Potential soil compaction forty years after logging in northeastern California,"
Great Basin Naturalist: Vol. 48
, Article 17.
Available at: http://scholarsarchive.byu.edu/gbn/vol48/iss1/17