Designing Low-Impact Operations
Best Management Practices (BMPs) are guidelines designed to ensure that the environment, particularly water quality, is protected. The guidelines cover road construction and maintenance, harvesting, site preparation, and subsequent silviculture. All of the Southern states have these BMP guidelines (see Forestry BMP website).
The most important guidance that these BMPs offer is to think and plan before acting. Forethought will avoid unnecessary site disturbance or damage and minimize the expense of ameliorating any damage that occurs. For many landowners, using a professional registered forester to assist in development of a management plan is often a good place to begin since the professional has intimate knowledge of the BMPs for the area. Secondly, select a professional logger before undertaking any logging operations as this will also ensure BMPs are followed. Note that the responsible parties for maintaining water quality include the landowner and any involved professional forestry practitioners.
While BMPs are specifically directed towards maintaining water quality, they will have indirect impacts on other forest resources such as wildlife habitat, clean air, aesthetics, and general environmental quality.
Although specific BMPs for bioenergy harvesting are not available, current BMPs for roading and harvesting and streamside management will be generally applicable.
Roads and Harvesting
Well-constructed and maintained and carefully located roads and access tracts are very important as they are frequently big sources of stream sediment. BMPs usually recommend very careful road design that avoids, as far as possible, stream management zones (SMZs). Construction and other works should be used that minimize erosion and other environmental effects such as flooding wetter areas. Drainage of roads is critical as is any water crossing. Road maintenance measures are also included in BMPs.
Harvesting operations require careful design. Location of landings and skid trails is often critical to avoid erosion and impacts on water quality. Logging close to streams needs careful attention and any logging debris needs to be removed from the stream. Intensive biomass harvesting may not be possible in SMZs. At landing sites or along roads, piles of biomass, collected for later chipping, need to be located so as not to lead to contamination of drains and streams.
BMPs for SMZs often require, for both intermittent and permanent streams, minimal widths of about 50 feet. Mechanical site preparation is generally excluded from SMZs. Residue collection of clearcut sites would be very limited in SMZs as equipment needs to be excluded from these areas. Similarly intensive biomass harvesting of small trees and shrubs may not be allowed in SMZs as there is a need to maintain the integrity of these sites, including a defined minimum of forest canopy.
Site protection and sustainability
Protection of the site from erosion is a critical aspect of ensuring sustainability. Thus BMPs often restrict the slope where mechanical site preparation should be used and also specify the use of along-the-contour operations. The intensive harvesting of residue biomass at clearcutting will need special attention on slopes and may be restricted on sites that are not considered suitable for mechanical site preparation. Wetlands will also need special care and attention and may not be suitable for some biomass operations.
As intensive biomass harvesting takes more nutrients from the site than normal logging operations, the return of the ash to the site after combustion, or perhaps the application of fertilizers, is often recommended. These operations need to be carried out so as to avoid the contamination of waterways. The section on Environmental Sustainability has more information on Designing Low-Impact Operations, including a compilation of state BMP websites and a comprehensive region-wide BMP website.
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