Intermediate Treatments

• Intermediate treatments

  Any silvicultural manipulation of forest vegetation occurring after establishment of regeneration and prior to final harvest of the stand (or cohort)
• Intermediate treatments

  • Designed to enhance stand composition, structure, growth, health, quality, and the production of specific benefits desired by the landowner
  • Can be non-commercial, requiring outright investment, or commercial, providing monetary income
• Timber stand improvement (TSI)


  Refers to non-commercial intermediate treatments
• Intermediate treatments

  • Release
  • Thinning and improvement
  • Salvage and sanitation
  • Pruning
• Cutting

  The primary silvicultural tool to manipulate forest vegetation and control forest development to satisfy landowner property goals and stand management objectives
• Methods to kill undesirable plants and control competition

  • Cutting
  • Girdling
  • Physically remove the plant from the soil
  • Fire
  • Herbicides
• Cutting

  • Most effective against species that don't sprout
  • Species that sprout may require repeated treatments to effectively control
  • Cutting in late spring and summer is most effective
  • Relatively expensive, unless a product can be harvested
• Girdling

  • Most effective against species that don't sprout
  • Most effective when done in late spring and summer
  • Generally applied only to trees greater than 4 inches dbh
• Physically remove the plant from the soil

  • A very effective but expensive method
• Fire

  • Usually kills trees by girdling
  • In Wisconsin, generally not currently used for intermediate treatments for sustainable forest management
• Herbicides

  • Very effective, and often the most inexpensive method
  • Methods of application include: aerial spraying, ground-level foliar spraying, basal spraying, stump application, and bark incisions
  • Herbicides are toxic chemicals. Toxicity can be highly selective and short-term, depending on the herbicide used. Products and guidelines change rapidly. It is imperative that label directions be followed. Select the appropriate product for the job and determine the best method and rate of application. Local regulations governing herbicide use are highly variable
• Release

  A treatment designed to free young trees (saplings and seedlings) from undesirable, usually overtopping, competing vegetation
• Release

  • Purpose is to regulate species composition and to improve growth and quality
  • Designed to provide potential crop trees with sufficient light and growing space, by freeing their crowns and controlling competition
• Assessing needs and planning release operations

  1. Predict how the vegetation, both the desired species and the competition, will respond and develop (e.g. relative growth rates and health)

  2. Evaluate biological and economic costs and benefits of different treatments and intensities (including no action)
• Complete release

  Entire layers of competing vegetation are controlled (kill or retard growth) to allow the desired species to gain dominance
• Partial release

  Release only selected exceptional individuals (crop trees)
• Partial release

  1. Determine minimum crop tree selection criteria, based on landowner objectives, and tree species, vigor, quality, and health

  2. Remove all trees with crowns that touch or interfere with each crop tree. A 5-7 foot opening around each crown is often recommended

  3. Control only direct competitors. Remove only what is necessary to accomplish the purpose; there is no need to eliminate any plant that is not going to suppress, endanger, or hamper the growth of desired individuals

  4. In sprout clumps, cut all but the best one or two stems
• When needed, release operations should be implemented early in the life of the stand, typically before 15 years of age
• Types of release treatments

  • Weeding
  • Cleaning
  • Liberation
• Weeding

  A release treatment that eliminates or suppresses undesirable vegetation (including shrubs and herbs) regardless of crown position
• Cleaning

  A release treatment designed to free favored trees from less desirable individuals (trees) of the same age class that overtop them or are likely to do so
• Liberation

  A release treatment designed to free favored trees from competition with older, overtopping trees
• Removing older, overtopping trees

  • Effective methods are cutting, girdling, and applying herbicides
  • Cutting may allow the realization of income, but protection of the young stand from felling and harvesting operations is critical
  • Care should be taken that following liberation the increase in sunlight does not result in intense crown competition from sprouts or the release of fast growing weed species
• Thinning


  A cultural treatment conducted in stands past the sapling stage to reduce stand density, primarily to improve tree growth, enhance tree health, or recover potential mortality
• Thinning

  • Entails the removal of trees to temporarily reduce stocking to concentrate growth on the more desirable trees
  • Normal thinning does not significantly alter the gross production of wood volume
  • Thinning does impact stand growth, development, and structure
  • Provides the main method, implemented between regeneration and final harvest, to increase the economic productivity of stands
  • Individual thinnings can be commercial or non-commercial (TSI), depending on landowner objectives and local markets for materials cut in the thinning operation
  • Regeneration is not an objective of thinning; overstory gaps are small and should close rapidly
• Objectives of thinning

  • Enhance the vigorous growth of selected trees through the removal of competitors
  • Enhance tree health
  • Harvest most merchantable material produced by the stand during the rotation
• Application of thinnings

  • Harvest anticipated losses of merchantable volume
  • Yield of income and control of growing stock during rotation
  • Increased value from rapidly growing larger diameter trees
  • Increased value from improvements in product quality
  • Opportunity to modify stand composition, prepare for the establishment of the next rotation (manipulate sources of regeneration), and reduce the risk of damage (maintain more vigorous and structurally sound trees)
• Crown classes

  • Dominant
  • Codominant
  • Intermediate
  • Overtopped
• Improvement cutting

  The removal of less desirable trees of any species in a stand of poles or larger trees, primarily to improve composition and quality to achieve landowner goals and objectives
• Dominant (D)


  • Medium-sized crowns that are often crowded on the sides
• Intermediate (I)


  • Shorter than dominant and codominant, but have crowns extending into the crown cover formed by codominant and dominant trees
  • Receive a little direct light from above, but none from the sides
  • Have small crowns that are considerably crowded on the sides
• Overtopped (O)


  • Also called suppressed, are trees with crowns entirely below the general level of the crown cover
  • Receive no direct light either from above or from the sides
• Improvement cutting

  1. Removal of less desirable trees of any species in a stand of poles or larger trees

  2. To improve composition and quality to achieve landowner goals and objectives

  3. Trees are removed to encourage the growth of more desirable trees within or below the main canopy

  4. Trees considered for removal include undesirable species, trees of poor vigor, trees of poor quality, and injured or unhealthy trees (risk)

  5. Potential crop trees should be preferred species and relatively well formed, vigorous, and healthy
• Improvement cutting is usually applied in stands that have been unmanaged, neglected, or poorly managed
• Improvement cutting is essentially a delayed release treatment in some cases
• Improvement cutting removes undesirable material and sets the stage for productive management to accomplish landowner objectives
• In cases where the current stand is of such poor quality that rehabilitation is untenable, the preferred choice may be to initiate regeneration to develop a vigorous, new stand. Improvement cuttings should be implemented as soon as possible.
• Improvement cuttings are preliminary operations leading to systematic thinnings and reproduction methods
• In most cases, stand improvement can be completed in one to three operations
• Improvement cuttings can be commercial or non-commercial, depending on landowner objectives, treatment intensity, tree characteristics, wood quality, and local markets