Site Preparation
An effort has been made to italicize technical words or phrases and clearly define them in the glossary.
Rapid regeneration of forestland is both economically and environmentally important. Root systems help stabilize soils and thereby reduce the risk of erosion. Trees also intercept water and impede storm water runoff. Many sites require some type of treatment to accomplish quick and effective regeneration of the desired tree species, or to reduce some undesired effects of logging.
Prior to artificial regeneration, a site preparation method is usually chosen that enhances seedling survival and/or controls competing vegetation. Sites may also be prepared simply to make an area more amenable to planting.
For natural regeneration, certain site preparation methods may enhance sprouting or seed germination.
Many site preparation techniques are available. The technique used depends on soils, slope, condition of the site, natural vegetation, crop tree species, and cost. Soils, slope, and ground cover are three principal factors that determine the potential for erosion on any site. Soils with a shallow surface layer (A1) generally have limited capacity to absorb water and are more likely to erode. Steeper slopes provide rainwater runoff more velocity, and thus energy, to erode soils. Ground cover helps hold soil in place and dissipates some of the energy of rainfall.
Site preparation techniques can be grouped into three categories: mechanical, chemical, and prescribed fire.
Mechanical Site Preparation
is often described in terms of its intensitythe degree to which it disturbs the soil. Methods vary from low to very high intensity. High intensity is defined as soil disturbed and exposed on more than 50% of the site. Disking and bedding are examples of high intensity methods. Chopping is a low intensity method. Some combinations of methods, for example, shear-rake-disk, are considered more intensive because they expose more soil. Erosion potential increases with higher intensity methods, especially on sloping lands. High intensity mechanical methods are most appropriate on flat land and gentle slopes. Low intensity methods may be appropriate on moderate slopes.Chemical Site Preparation
Many herbicides are available for preparing forest sites. They control most undesirable vegetation in place, and do not disturb the litter. Because herbicides are selective, the prescription should carefully consider the vegetation to be treated. Most herbicides may be successfully applied either from the ground or aircraft. When used properly, chances of off-site impacts are minimal.Prescribed Fire
is often used in conjunction with mechanical or chemical site preparation, but it may be used alone. A properly conducted prescribed burn, which consumes a portion of the litter without altering the soil, only slightly increases the potential for erosion. Very hot fires which expose much mineral soil on steep slopes may significantly increase erosion potential.In order to identify methods appropriate for certain sites, percent slope is used in the following guidelines. However, the measures of slope are only guidelines because other factors must also be taken into consideration. Furthermore, slope usually varies over a site being reforested. If in doubt about the appropriate method to use, seek the advice of a licensed forester or other qualified professional.
BMPs
- On slopes 5% or less, any method may be used.
- On slopes 6-10%, intensive mechanical methods should follow the contours of the land.
- On slopes 11-20%, mechanical methods, other than chopping, should follow the contours of the land. If erosion potential appears high, leave untreated strips 5 to 10 feet wide approximately 100 feet apart.
- On slopes 21-30%, use only herbicides, prescribed fire, or low intensity mechanical methods.
- On slopes greater than 30%, use only herbicides, hand tools, and/or prescribed fire, but be aware that extremely hot fires may significantly increase erosion potential.
- Herbicides and prescribed fire are acceptable site preparation methods on all slopes if conducted properly.
- Where accelerated erosion is likely, use methods which leave logging debris and other litter scattered over the site.
- Minimize moving soil into windrows and piles.
- Break windrows to allow for fire control equipment, wildlife crossing, and drainage of surface runoff.
- Prepare planting beds only as high as necessary for seedling survival.
- When constructing beds on sloping land greater than 5%, follow land contours and break frequently within the beds.
- Construct water bars or use other methods to prevent erosion in firebreaks and protective lines that have been pushed around herbicide application sites.
- Leave vegetation and limit soil disturbance in gullies that have stabilized and are no longer eroding.
- Contact a licensed forester or other qualified professional for advice on stabilizing gullies that continue to erode.
- Contact a licensed forester or other qualified professional for advice on site preparation burning.
- Refer to Streamside Management Zones for specific restrictions.
- Refer to Prescribed Burning and Pesticides for specific guidelines concerning burning and pesticide application.
- Leave a vegetated buffer strip at least 10 feet wide on edges of public roads to catch soil particles and slow runoff.
Avoid
- Any mechanical methods on slopes greater than 30%.
- Intensive mechanical methods on slopes greater than 20% or on other sites with high potential for erosion (considering soil, slope, and ground cover).
- Constructing windrows, on slopes greater than 5%, which will funnel surface runoff into perennial, intermittent, or ephemeral streams.
- Mechanically preparing sites when equipment will cause excessive soil disturbance due to saturated or very wet soil conditions.
- Blocking any drainage with beds, windrows, or similar structures.
- Connecting planting beds to ditches if jurisdictional wetlands will be converted to uplands.
Contents
Streamside Management Zones /
Forest Road Construction /
Timber Harvesting /
Stream Crossings /
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