Logging Effects on Soil

Logging Effects on Soil
April 5, 2011
Logging has many effects on the soil. Some of these can be prevented or lessened by using different techniques or specialized equipment, but negative soil impacts are going to happen on a logging site no matter what a logging crew does to prevent it. It is important for foresters and loggers to understand the effects of logging on soil. Some of the things that logging does to soil is soil erosion and soil compaction.
Erosion is the process of weathering and transport of solids in the natural environment or their source and deposits them elsewhere. It usually occurs due to transport by wind, water, or ice, by down-slope creep of soil and other material under the force of gravity. Erosion can also be done by living organisms, such as burrowing animals, in the case of bioerosion. Erosion is a natural process, but it has been increased dramatically by human land use, especially in Industrial agriculture, logging, and urban sprawl. Land that is cleared of vegetation generally experiences a significantly greater rate of erosion than that of land under natural vegetation, or land used for sustainable forestry practices. Excessive erosion causes serious problems, such as receiving water sedimentation, ecosystem damage and outright loss of soil. One example of a logging site where erosion can be harmful to an organism is near trout or salmon streams. If silt and clay erodes into streams it may cover up gravel bars that these fish use to spawn.
Wisconsin loggers have worked hard to prevent erosion on logging sites. The best management practices hand book for water quality has many useful techniques that help diverge soil from washing into streams. There is a list of drainage structures that the BMP manual suggests such as pipe culverts, open-top culverts, broad based dips, and water bars. Building these structures can take the better part of a day in the case of a pipe culvert, or maybe just the better part of an hour in the case of the water bar.
Soil compaction on logging sites is a quite common problem, which is mostly due to large equipment moving over the terrain. Compacted soil resists absorption of water, restricts movement of air around the roots, and produces a physical barrier to the development of roots. One main procedure that loggers use to prevent soil compaction is logging when the ground is frozen. Logging when the ground is frozen will limit the impact of heavy machinery on the ground. Soil compaction has become such a big concern that heavy machinery companies such as John Deere have made logging equipment with wide tracks or extra wheels to decrease the pounds per square inch that they put on the ground. A few examples of these machines are the 120C model from John Deere excavator with 4.5 PSI. Or John Deere’s 1710D forwarder, this forwarder puts just 7.7 PSI on the front tires and 15.8 PSI on the rear tires. But with the addition of optional Enviro Tracks the PSI is lowered to 5.1 PSI in the front tires and 8.8 on the back tires. If you’re talking about harvesters the 759JH tracked harvester from John Deere puts between 7 and 8 PSI on the ground depending what options have been put on it. To put this all in perspective a six foot tall man with a medium build puts 8 PSI on the ground with every step.
There is no doubt that logging has an effect on the environment, but it is obvious that loggers are trying to limit the negatives of these effects. Many times logging jobs mimic a natural disturbance that can benefit early succession organisms. With proper management, and careful harvesting practices we can keep jobs in the woods and allow for a healthy ecosystem.