Timber Harvesting
Water Quality
BMPs :
Planning,
Execution,
Follow-up
Avoid
On-Site Impacts (Non-Water Quality)
BMPs :
Planning,
Execution,
Follow-up
An effort has been made to italicize technical words or phrases and clearly define them in the glossary.
Executing an environmentally responsible and economically efficient timber harvest operation, especially one near sensitive sites, requires a thorough understanding of the land, the trees, the capabilities of the logger and logging equipment, and the markets for timber products. Landowners are encouraged to seek the advice of a licensed forester or the South Carolina Forestry Commission to plan and execute timber harvests carefully. Timber harvesting contracts should specify compliance with BMPs.
Harvesting trees is not just the end of the growing cycle of a forest; it is the start of the next generation. Many commercial tree species need exposed mineral soil and the direct sunlight of an open area for their seeds to germinate and successfully become established. Harvesting operations usually provide both of these conditions. To minimize water quality impacts of harvesting, the landowner or his agent should carefully consider road location, stream crossings, and the method of regeneration before logging begins.
It is necessary to protect sensitive areas, plan for regeneration, and consider the areas beyond the actual harvest site if negative environmental impacts are to be avoided. For instance, bottomland hardwood sites, Carolina Bays, and other swamps differ from upland forest types in that their soils are wet for most, if not all, of the year. They are frequently connected directly to an aquatic system; they often have overland water flow from nearby stream flooding; and they may accumulate sediments, nutrients, and pollutants from upstream erosion and runoff. These areas may require special harvesting equipment and/or special harvesting techniques.
Water Quality
The primary water quality impact associated with timber harvesting is the degradation of aquatic habitat quality due to increased sediment inputs and elevated water temperatures. The following BMPs are designed to minimize harvesting impacts on water quality.
BMPs
Planning
- Carefully plan the harvest to minimize the number of stream crossings required.
- Identify locations for stream crossings where impacts to the stream are likely to be minimal. Follow all stream crossing BMPs.
- Identify areas that are the most acceptable log deck locations (stable soil). If it is necessary to stabilize areas for decking, limit the amount of area filled to the smallest practical size.
- Identify sensitive areas such as SMZs, ephemeral streams, and erosive soils.
Execution
- Establish SMZs adjacent to all perennial, intermittent streams, and lakes.
- Take precautions to minimize excessive rutting in active floodplains, bottomland hardwood swamps, and erosive slopes. If soils are excessively wet, special techniques are available to minimize rutting, soil compaction, and/or interference with normal flow of water.
Examples of these techniques:
a. debris or mats on skid trails
b. high flotation equipment
c. concentrating logs in felling and forwarding operations to minimize the number of skid trails
d. other low-impact techniques - Cease harvesting operations when overland water flow impairs beneficial uses of water bodies downstream from the harvesting operation. Turbid water flowing from the site is a useful indicator of possible impairment of beneficial uses downstream.*
- Lay out skid trails to minimize water quality impacts (see Skid Trails ).
- Service equipment away from water bodies and wetlands when possible.
Follow-up
- Remove any blockage intended for temporary crossing in a bottomland hardwood slough or drain if it is directly connected to a perennial stream.
Avoid
- Locating log decks in sensitive areas.
- Skidding beside or within a stream channel.
- Skidding straight up and down (perpendicular to the contour) on steep hillsides if mineral soil is exposed. Use BMPs such as water bars, soil stabilization, etc., where this type of skidding is unavoidable.
- Skidding across perennial or large intermittent streams, except over an adequately designed and constructed ford, culvert, or bridge (see Stream Crossings ).*
- Skidding over small intermittent or ephemeral streams during wet conditions unless the banks (if present) have been protected by placing woody material in the water course (see Stream Crossings ).*
- Removing culverts from stream channels following logging when the crossing will be used within ten years.
- Using soil fill, either alone or in combination with woody debris fill, for skid trail stream crossings.
* Braided stream systems typically have multiple, interconnected channels and a high water table for much of the year. Logging under these conditions often requires the use of specialized logging equipment. BMPs concerning stream crossings are not always applicable when crossing braided streams due to their unique characteristics. Increased turbidity downstream from a logging operation should not be of a duration or magnitude to impair the beneficial uses of the water body. Upon completion of the logging operation, block any channels that were created by skidding logs across the terrain in braided stream systems.
On-Site Impacts (Non-Water Quality)
Harvesting sites with stable, non-erosive soils that are not closely associated with streams has little potential to impact water quality. However, logging during wet conditions can cause exposure of mineral soil and rutting which may result in erosion, soil compaction, or puddling. Such soil disturbance may cause a loss in site productivity. These impacts can often be reduced with site preparation techniques. Because rutting may impact site productivity on certain sites, landowners should consider logging under drier conditions if they do not wish to bear the expense of site preparation or skid road rehabilitation.
Rapid reforestation is an effective means of improving the visual impact of harvest operations. Regeneration techniques such as single-tree selection, patch clearcuts, or shelterwood harvests can be used to minimize visual impact. These systems, however, may be less efficient than clearcutting for regenerating the site, and they require additional logging entries which can further impact site productivity.
Two ways to improve the initial visual impact of a clearcutting operation are:
- Leave a strip of trees along well-traveled highways;
- Limit the size of the area to be harvested at any one time. (This is probably the most effective way to reduce negative visual impact.)
BMPs
Planning
- Where clearcutting is the desired harvesting method, special emphasis should be given to the timber harvest planning process. Consider surrounding land use, wildlife habitat, and aesthetics, especially when clearcuts approach 100 acres.
- Plan skid trails to occupy the least amount of area possible to log the site effectively (See Skid Trails).
Execution
- Use high flotation harvesting equipment or another low impact harvesting system if excessive rutting is occurring due to wet soil conditions (see Rutting ). Bunching stems and placing them near the primary skid trail can reduce excessive rutting. Log a dry alternative site if possible.
- Use woody debris, mats, or other techniques to stabilize skid trails if excessive rutting is occurring.
- Take steps to avoid depositing mud on paved roads.
Follow-up
- Site prepare to reduce on-site impacts.
- Create conditions that are conducive to rapid regeneration.
- Clean up and/or contain fuel and oil spills immediately. Comply with state and federal regulations concerning reporting of spills.
- Dispose of oils, lubricants, their containers and other wastes according to local, state, and federal regulations.
- Report any fuel, oil, or chemical spills to the Emergency Response Unit of the Department of Health and Environmental Control (opens in a new window) at 803-253-6488.
Skid Trails
- Control water flow on skid trails with broad-based dips, wing ditches, or water bars.
- Skid logs uphill, when possible, so surface runoff will be dispersed as it flows downhill. However, skid trails should not be located perpendicular to the contour unless appropriate BMPs are used.
- Retire primary skid trails on erosive slopes by installing water bars and seeding them upon completion of logging.
- Construct bladed skid trails according to LU road specifications except for the slope restrictions.
To reduce harvesting impacts on sites that will not be treated with mechanical site preparation:
- Plan primary skid trails on selective cuts so that they can be used with each successive harvest of the area.
- Locate primary skid trails so they occupy the least amount of area to log the site effectively.
- Concentrate skidding on a few trails to minimize overall soil compaction on fine textured (clay or loamy) soils.
Rutting
During dry conditions, rutting occurs mostly in isolated, moist areas, or on primary skid trails where repeated skidder traffic gradually compacts the soil. Usually these ruts are not a significant concern. However, when certain soils are moist or wet, rutting can be a significant problem, especially if natural regeneration methods are planned. Rutting is a highly visible impact of logging, but the effects of rutting on site productivity are poorly understood over the wide range of soil types in South Carolina.
Because of the potential impacts on certain soils, precautions should be taken during planning and conducting timber harvesting to minimize depth of rutting and the amount of area with ruts. *
* See glossary for definitions of rutting and excessive rutting.
Contents
Streamside Management Zones /
Forest Road Construction /
Stream Crossings /
Site Preparation /
Reforestation /
Prescribed Burning /
Pesticides /
Fertilization /
Minor Drainage /
Endangered Species Act /
Additional Management Options: Wildlife Management /
Glossary
Forest Management/ Reference Resources / Environmental Forestry/ Braided Stream Systems