Protecting your forest trees and soil during spring thaw

In many rural areas of Michigan, the effects of snow melt and spring thaw can make the soils in your woodland vulnerable to rutting from vehicle traffic and can damage valuable tree roots attached to trees adjacent to two-track trails and wood roads.

According to loggers, spring thaw goes by different names depending upon where you live. Quintessential New Englanders refer to it as mud season, while many Michigan woods-workers refer to it simply as Spring break-up.

The recent bout of unseasonably warm weather across Northern Michigan over the last few weeks has caused the snow cover to quickly evaporate from our forest and fields. Until that moisture works its way through the soil and dries the ground out, loggers, maple syrup producers and other woods workers need to be careful when they operate any type of wheeled equipment, such as tractors, trucks or off-road vehicles, in the woods. The danger of creating ruts or sunken tracks from wheeled vehicles is most extreme at this time of year. Put simply, rutting damages the soil in a number of ways and can also injure feeder roots of forest trees growing nearby.

Excessive rutting can destroy the soil structure and effect the way soil drains water because it destroys the natural system of pores and clods that exist in native, undamaged soil. Rutting can also alter soil drainage patterns across the soil surface because ruts can act as channels to divert water into new pathways or areas that can run-off and have an erosive effect over time. If that soil sedimentation created from erosive rutting reaches the waters of streams or rivers, it can also have an impact on the ecology of the streambed or river bottom.

Deep ruts can also damage the root systems of trees growing adjacent to two-track trails or woods roads. Considering that the majority of a tree’s feeder roots that allow trees to absorb water and minerals are located in the top 3 feet of soil, excessive rutting can impair a tree’s ability to grow normally and lead to branch dieback or other problems.

If travel through wet areas in your woods cannot be avoided at this time of year, there are Best Management Practices (BMP’s) that can be undertaken to minimize damage to the soil. For example, during harvest, many loggers will use the tops and branches from felled trees to build brush mats over wet areas. These brush mats help protect the soil by helping to float heavy logging equipment and keep it from impacting with the soil.

For areas of your woods that are perennially wet and where roads cannot be re-routed, the use of geotextile engineering fabric can really help. Geotextile material comes in wide rolls that can be cut and put down over an entire section of a road. Once the geotextile is in place, several inches of road gravel and fill is placed on top. The end result is a section of roadway that can consistently support the weight of heavy equipment on a fairly regular basis without causing rutting and damage to tree roots. Loggers and maple syrup producers who have used geotextile material have found it very effective practice in avoiding damage inside woods and sugar bushes.

Finally, good site planning when laying out woods roads and trails at the outset of tree harvesting or other types of woods operations is key. Maps and plans that show the location of streams, creeks, wetlands and other surface features should be developed so that roads can be laid out to avoid many of these wet spots. Furthermore, all operations should be located at least 100 feet away from the edges of rivers and streams to maintain a Riparian Management Zone that protects the fragile areas around waterways.

For more information, extension bulletin E-2770, “Water Quality Best Management Practices on Forest Lands” can be purchased from the MSUE Bookstore. Another excellent reference is the “Sustainable Soil and Water Quality Practices on Forest Land” published by the Michigan Department of Natural Resources. This is a comprehensive booklet covering Michigan laws and regulations regarding working in the forest environment as well as useful guidelines and practices to help sustain water and soil resources in the forest.

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