2E – Timber Harvesting
The timber harvesting management measure consists of implementing the following:
- Element 1. Conduct timber harvesting operations with skid trails or cable yarding following layouts determined under Management Measure 2A.
- Element 2. Install landing drainage structures to minimize erosion and prevent sedimentation.
- Element 3. Construct landings away from steep slopes and reduce the likelihood of fill slope failures. Protect landing surfaces used during wet periods. Locate landings outside Streamside Management Areas (SMAs).
- Element 4. Protect stream channels and significant ephemeral drainages from logging debris and slash material.
- Element 5. Use appropriate areas for petroleum storage and equipment maintenance and service. Establish procedures to contain and treat spills. Recycle or properly dispose of all waste materials.
- For cable yarding
- Element 1. Limit yarding corridor gouge or soil plowing by properly locating cable yarding landings.
- Element 2. Locate corridors for SMAs following Management Measure 2B.
- For groundskidding
- Element 1. Within SMAs, operate ground-skidding equipment only at stream crossings. In SMAs, fell and endline trees to avoid sedimentation and damage to residual vegetation.
- Element 2. Use improved stream crossings for skid trails that cross flowing drainages. Construct skid trails to disperse runoff and with adequate drainage structures.
- Element 3. On steep slopes, use cable systems rather than ground-skidding where ground-skidding may cause excessive erosion.
The following are practices that can be used to minimize the adverse environmental impacts of timber harvest:
- Felling trees
Trees should be felled in a direction away from watercourses and lakes. Also, damage to desirable residual trees and tree seedlings of commercial species should be avoided during felling and while operating heavy equipment. Slash and debris from timber operations should not be bunched adjacent to residual trees required for silvicultural or wildlife purposes or placed in locations where they could be discharged into a Class I or II watercourse or lake (CDF, 2003).
- Skidding logs
Logs should be skidded uphill to log landings whenever possible, and the ends of the logs should be raised to reduce rutting and gouging. This practice disperses water on skid trails away from the landing. Skidding uphill lets water from trails flow onto progressively less-disturbed areas as it moves downslope, reducing the likelihood of erosion. Skidding downhill concentrates surface runoff on lower slopes along skid trails, resulting in significant erosion and sedimentation hazard (USEPA, 2002). If it is not possible to skid uphill, logs should be skidded along the contour (perpendicular to the slope), and skidding should be avoided on slopes greater than 40 percent. Following the contour reduces soil erosion and encourages revegetation. Skid trail layouts that concentrate runoff into draws, ephemeral drainages, or watercourses and skidding up or down ephemeral drainages should be avoided. Endlining, using care to avoid soil plowing or gouging, should be used to winch logs out of SMAs, or, alternatively, trees can be felled directionally so the tops extend out of SMAs, allowing the trees to be skidded without having to operate equipment within the SMAs. Ground skidding should be suspended during wet periods, when excessive rutting and churning of the soil begins, or when runoff from skid trails is turbid and no longer infiltrates within a short distance from the skid trail. Further limitation of ground skidding of logs, or the use of cable yarding, might be needed on slopes where there are sensitive soils and/or during wet periods.
- Heavy equipment operation
Tractors should be operated in a manner that complies with CDF regulations. Heavy equipment with a blade should not be operated on skid roads or slopes that are so steep as to require the use of the blade for braking. Heavy equipment should not be used on slopes steeper than 65 percent, slopes steeper than 50 percent where the erosion hazard rating is high or extreme, and slopes over 50 percent that lead without flattening to sufficiently dissipate water flow and trap sediment before it reaches a watercourse or lake. Heavy equipment should also not be used on unstable areas, but if such areas are unavoidable, the Registered Professional Forester (RPF) should develop specific measures to minimize the effect of operations on slope instability.
Tractor roads should be limited to the minimum necessary extent and width for removal of logs. Existing tractor roads should be used instead of constructing new tractor roads. Where tractor roads are constructed, timber operators should use tractor roads only, both for skidding logs to landings and on return trips.
- Spill prevention and waste management
Equipment used in timber operations should not be serviced in locations where servicing will allow grease, oil, or fuel to pass into lakes or watercourses. Non-biodegradable refuse, litter, trash, and debris resulting from timber operations should be disposed of in a manner approved by State and local authorities. Practices should be implemented that prevent mobilization by rainfall or runoff of pollutants from wastes that are temporarily stored on the site.
- Cable yarding
The natural topography and timber types should be used to maximum efficiency so that cable yarding operations protect residual trees. Residual trees required to be left upon completion of timber operations should not be used for rub trees, corner blocks, rigging, or other cable ties unless effectively protected from damage. Tight-lining for the purpose of changing location of cable lines should not be used unless such practice can be carried on without damaging residual trees. Tractors should not be used in areas designated for cable yarding except to pull trees away from streams, to yard logs in areas where deflection is low, to construct firebreaks and/or layouts, and to provide tail-holds. Cabling systems or other systems should be used when ground skidding would expose excess mineral soil and induce erosion and sedimentation. Use high-lead cable or skyline cable systems on slopes greater than 40 percent and on average-profile slopes of less than 15 percent (the latter to avoid soil disturbance from sidewash).
Cable yarding should be avoided in or across watercourses. When cable yarding across streams cannot be avoided, full suspension should be used to minimize damage to channel banks and vegetation in the SMA. Cableways should be cut or cleared across SMAs where SMAs must be crossed. This reduces the damage to trees remaining and prevents trees next to the stream channel from being uprooted.
Waterbreaks should be installed on skid trails and tractor roads no later than the beginning of the winter period of the current year of timber operations. If logging occurs during the winter, waterbreaks should be installed before the end of the day if the U.S. Weather Service forecasts a "chance" (30 percent or more) of rain before the next day, and prior to weekends or other shutdown periods. Waterbreaks should be constructed concurrently with the construction of firebreaks and immediately upon conclusion of use of tractor roads, roads, layouts, and landings that do not have permanent and adequate drainage facilities, or drainage structures. Waterbreaks should be cut diagonally a minimum of 15.2 centimeters (cm) (6 inches) into the firm roadbed, cable road, skid trail, or firebreak surface, and a continuous firm embankment of at least 15.2 cm (6 in.) in height should be shaped immediately adjacent to the lower edge of the waterbreak cut. According to California Forest Practice Rules, the maximum permitted distance between waterbreaks is based upon the road gradient and soil erosion hazard rating, and varies from 50 to 300 feet.
Waterbreaks should be located to allow water to be discharged into some form of vegetative cover, duff, slash, rocks, or less erodible material. They should be constructed so that water will be discharged and spread to minimize erosion. Where waterbreaks cannot effectively disperse surface runoff, other erosion controls should be installed as needed to comply with CDF regulations. Waterbreaks or any other erosion controls should be maintained on skid trails, cable roads, layouts, firebreaks, abandoned roads, and site preparation areas during the prescribed maintenance period and during timber operations, or at least once per year. The CDF may prescribe a maintenance period extending 3 years after timber operations are complete (CDF, 2003).
- Watercourse crossings
Watercourse-crossing facilities on tractor roads should be kept to a minimum. A prepared watercourse crossing using a structure such as a bridge, culvert, or temporary log culvert can be used to protect the watercourse from siltation where tractor roads cross a watercourse. Crossings should be designed to allow for the unrestricted passage of all life stages of fish that could be present in the watercourse. Watercourse-crossing facilities on tractor roads not constructed to permanent crossing standards should be removed before the beginning of the winter period.
- After harvesting
Skid trails should be retired by installing water bars or other erosion control and drainage devices, removing culverts, and mulching and reseeding. Logging slash should be distributed through the skid trails to supplement the water bars. Cross drains can be built on abandoned skid trails to protect stream channels or side slopes. Logging slash should be distributed throughout skid trails to supplement water bars and seeding to reduce erosion on skid trails.
- The USDA Forest Service’s National Forest Timber Harvest must conform to the 1976 National Forest Management Act (NFMA). The NFMA requires that each national forest develop a comprehensive plan, using substantial public involvement and sound science, to guide future management. Many national forests are now working to revise those plans by addressing inadequacies, new information, changed conditions, and/or new issues or trends. Pacific Southwest Region manages the National Forests in California and assists the State and Private forest landowners in California, Hawaii and the U.S. Affiliated Pacific Islands.
- California Forest Stewardship Program - California Departlment of Forestry and Fire Protection
- USEPA, Watershed Academy Web: Forestry Best Management Timber Harvesting is a forestry management module, with a series of interactive fact sheets on forestry management practices. The Website includes diagrams, photographs, and review questions.
- Wisconsin Department of Natural Resources and University of Wisconsin, Madison, Forestry Best Management Practices for Water Quality series, provides information on timber harvesting practices to protect water quality.
CDF. 2003. California Forest Practice Rules. California Department of Forestry and Fire Protection, Resource Management, Forest Practice Program, Sacramento, CA.
Meghan, W.F. 1980. Nonpoint source pollution from forestry activities in the Western United States: Results of recent research and research needs. In U.S. Forestry and Water Quality: What Course in the 80s?, Proceedings of the Water Pollution Control Federation Seminar, Richmond, VA, June 19, 1980, pp. 92-151.
Sidle, R.C. 1980. Impacts of Forest Practices on Surface Erosion. Pacific Northwest Extension Publication PNW-195, Oregon State University Extension Service.
USEPA. 2002. National Management Measures to Control Nonpoint Source Pollution from Forestry. Pre-Final Draft. U.S. Environmental Protection Agency, Office of Water, Washington, DC.