FOREST MANAGEMENT WORKSHOP MANUAL
If a stand of trees is going to be managed on a continual
basis, there must be some type of road to allow access for
cultural operations and harvest. Unfortunately, any type of
road construction creates a variety of site disturbances that
tend to accelerate erosion and increase downstream
sedimentation. Low standard roads such as those used in logging
or strip mining are particularly troublesome because of such
factors as poor location and design and lack of erosion control
measures. In fact, the major source of sediment from erosion in
logging operations is from logging roads. As Federal and State
laws come in effect, more and more attention will have to be
given to this type of erosion. Public Law 92-500, the Federal
Water Pollution Control Act of 1977, has a Section 208 which
deals with non-point pollution. Non-point pollution, and
sediment is pollution from large areas which contributes to poor
water quality but the exact point at which it enters a stream
cannot be determined, as opposed to point source pollution from
a pipe which can be exactly pinpointed. Erosion from logging
roads is non-point pollution, and as time goes by, this type of
pollution will come more under government regulation. So as a
management plan is developed for a woodland tract, consideration
should be given to road locations designed to minimize erosion
and to avoid problems in the future.
Most of the potential erosion problems are caused by one or
more of these factors:
- Removal or reduction of vegetative cover.
- Destruction or impairment of natural soil structure and
- Decreased infiltration rates on parts of the road.
- Concentration of runoff or seepage water.
- Interception of subsurface flows by road cuts.
- Skidding uphill causes less erosion than skidding downhill.
Try to plan for hauling downhill on gentle slopes. On small
ownerships, one well located haul road with a well planned skid
road system, often provides access to the whole tract and
requires a minimum amount of land. Well planned road systems
are also aesthetically pleasing.
- Try to locate so that sustainded grades do not exceed 10%
(10' rise per 100'), short grades may run as high as 20% (20'
rise per 100'), but keep a maximum grade of at least 3% (3' rise
per 100'), to facilitate drainage. Do not locate roads in
streams and allow enough distance between the road and stream to
filter sediment. Cross streams at right angles. Do not
skid straight up and down slopes.
- This is the most important aspect of design. The most
common drainage device used are culverts. They can be open or
closed and are used more often on the main haul road. Open
culverts can be made of logs or boards to intercept surface
water and control rutting and gullying on the main haul road.
Closed culverts are used most effectively where water runs
continuously. Outsloping means sloping the road surface to
allow runoff to flow evenly across the road without collecting.
For safety, in steep terrain logging roads could be insloped and
water channelled to culverts and removed. An alternative to
culverts is broad-based dips. These are installed after the
basic roadbed is constructed. They are good for erosion control
on both skid roads and haul roads and can be used where road
grades do not exceed 10%. Here is a spacing formula for
Spacing=100 feet + (400/Road Grade %)
- This is mainly a problem of water control. Make sure that
culverts, dips, bridges, and outsloping are free to carry away
water. After logging, usually it's best to remove open wooden
culverts and install water bars. Seeding raw and denuded areas
reduces gullying and prevents erosion. Opening the canopy to
allow sunlight to reach the roadbed allows the road to dry out
quicker and helps vegetation become established. Careful
location and design can completely eliminate many road
maintenance problems and minimize others.
- Traffic regulation
- Traffic must be regulated for proper maintenance.
- Care after logging
- Immediately following logging, main haul roads and skid
roads should be smoothed and outsloped and drainage structures
should be cleaned. Major skid trails and log landings should be
seeded and have water bars or other drainage diversions
installed. (Refer to bibliography for reference listing best
management practices to control erosion on woodland).
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Last revised August 14, 1995.
Please send comments to: Duane Bristow (email@example.com)